| Message ID | 20220327123835.28329-3-aford173@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [1/5] dt-bindings: mmc: imx-esdhc: Update compatible fallbacks | expand |
Hello Adam, On 27.03.22 14:38, Adam Ford wrote: > The SDHC controller in the imx8mp has the same controller > as the imx8mm which supports HS400-ES. Change the compatible > fallback to imx8mm to enable it. I believe that's a shortcoming of the Linux driver, which should explicitly list fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. I find dropping compatibles problematic, because like Linux matching fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. I'd prefer that either the kernel driver gains extra compatibles or that the DTS lists extra compatibles and we refrain from dropping existing (correct) ones. What do you think? Cheers, Ahmad > Signed-off-by: Adam Ford <aford173@gmail.com> > --- > arch/arm64/boot/dts/freescale/imx8mp.dtsi | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi > index 794d75173cf5..d5ee1520f1fe 100644 > --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi > +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi > @@ -769,7 +769,7 @@ i2c6: i2c@30ae0000 { > }; > > usdhc1: mmc@30b40000 { > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > reg = <0x30b40000 0x10000>; > interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>; > clocks = <&clk IMX8MP_CLK_DUMMY>, > @@ -783,7 +783,7 @@ usdhc1: mmc@30b40000 { > }; > > usdhc2: mmc@30b50000 { > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > reg = <0x30b50000 0x10000>; > interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH>; > clocks = <&clk IMX8MP_CLK_DUMMY>, > @@ -797,7 +797,7 @@ usdhc2: mmc@30b50000 { > }; > > usdhc3: mmc@30b60000 { > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > reg = <0x30b60000 0x10000>; > interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>; > clocks = <&clk IMX8MP_CLK_DUMMY>,
On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: > > Hello Adam, > > On 27.03.22 14:38, Adam Ford wrote: > > The SDHC controller in the imx8mp has the same controller > > as the imx8mm which supports HS400-ES. Change the compatible > > fallback to imx8mm to enable it. > > I believe that's a shortcoming of the Linux driver, which should explicitly list > fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. > > I find dropping compatibles problematic, because like Linux matching > fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match > fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. > > I'd prefer that either the kernel driver gains extra compatibles or that > the DTS lists extra compatibles and we refrain from dropping existing > (correct) ones. > I would argue that imx7d is not correct since the IP blocks between imx7d and imx8mm have different flags/quirks. One of which includes HS400-ES, but there are other differences as well. > What do you think? From my understanding of the fallback compatibility strings is to avoid having to add more and more compatible strings to the drivers when they do not serve a functional purpose. Based On a conversation with Krzysztof [1], he suggested we update the YAML file based on the fallback, but he wanted NXP to give their feedback as to what the right fallback strings should be. Haibo from NXP sent me a hierarchy [1] which is what I used to update the YAML file. Based on the YAML file, the fallback in each DTSI file was updated to ensure the use of the proper IP block. adam [1] - https://lore.kernel.org/linux-arm-kernel/CAHCN7xLWoUGi-jfxR2a0gvEFkPT3USUEb+8U3CCqCb5wWEJ8xw@mail.gmail.com/T/ > > Cheers, > Ahmad > > > Signed-off-by: Adam Ford <aford173@gmail.com> > > --- > > arch/arm64/boot/dts/freescale/imx8mp.dtsi | 6 +++--- > > 1 file changed, 3 insertions(+), 3 deletions(-) > > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi > > index 794d75173cf5..d5ee1520f1fe 100644 > > --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi > > +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi > > @@ -769,7 +769,7 @@ i2c6: i2c@30ae0000 { > > }; > > > > usdhc1: mmc@30b40000 { > > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > > reg = <0x30b40000 0x10000>; > > interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&clk IMX8MP_CLK_DUMMY>, > > @@ -783,7 +783,7 @@ usdhc1: mmc@30b40000 { > > }; > > > > usdhc2: mmc@30b50000 { > > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > > reg = <0x30b50000 0x10000>; > > interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&clk IMX8MP_CLK_DUMMY>, > > @@ -797,7 +797,7 @@ usdhc2: mmc@30b50000 { > > }; > > > > usdhc3: mmc@30b60000 { > > - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; > > + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; > > reg = <0x30b60000 0x10000>; > > interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&clk IMX8MP_CLK_DUMMY>, > > > -- > Pengutronix e.K. | | > Steuerwalder Str. 21 | http://www.pengutronix.de/ | > 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | > Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
Hello Adam, On 28.03.22 12:47, Adam Ford wrote: > On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >> >> Hello Adam, >> >> On 27.03.22 14:38, Adam Ford wrote: >>> The SDHC controller in the imx8mp has the same controller >>> as the imx8mm which supports HS400-ES. Change the compatible >>> fallback to imx8mm to enable it. >> >> I believe that's a shortcoming of the Linux driver, which should explicitly list >> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >> >> I find dropping compatibles problematic, because like Linux matching >> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >> >> I'd prefer that either the kernel driver gains extra compatibles or that >> the DTS lists extra compatibles and we refrain from dropping existing >> (correct) ones. >> > > I would argue that imx7d is not correct since the IP blocks between > imx7d and imx8mm have different flags/quirks. One of which includes > HS400-ES, but there are other differences as well. The DTS currently says that an fsl,imx7d-usdhc is a subset of an fsl,imx8mm-usdhc. So a driver could treat both HW the exact same by focusing on the i.MX7D parts. Linux apparently did exactly that so far. Is this not accurate? >> What do you think? > > From my understanding of the fallback compatibility strings is to > avoid having to add more and more compatible strings to the drivers > when they do not serve a functional purpose. Based On a conversation > with Krzysztof [1], he suggested we update the YAML file based on the > fallback, but he wanted NXP to give their feedback as to what the > right fallback strings should be. Haibo from NXP sent me a hierarchy > [1] which is what I used to update the YAML file. Based on the YAML > file, the fallback in each DTSI file was updated to ensure the use of > the proper IP block. Myself I am in favor of moving to three compatibles instead of dropping one. For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, but for existing device trees, this may introduce needless potential breakage for other software that also uses Linux device trees. Cheers, Ahmad > > adam > > [1] - https://lore.kernel.org/linux-arm-kernel/CAHCN7xLWoUGi-jfxR2a0gvEFkPT3USUEb+8U3CCqCb5wWEJ8xw@mail.gmail.com/T/ > >> >> Cheers, >> Ahmad >> >>> Signed-off-by: Adam Ford <aford173@gmail.com> >>> --- >>> arch/arm64/boot/dts/freescale/imx8mp.dtsi | 6 +++--- >>> 1 file changed, 3 insertions(+), 3 deletions(-) >>> >>> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi >>> index 794d75173cf5..d5ee1520f1fe 100644 >>> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi >>> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi >>> @@ -769,7 +769,7 @@ i2c6: i2c@30ae0000 { >>> }; >>> >>> usdhc1: mmc@30b40000 { >>> - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; >>> + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; >>> reg = <0x30b40000 0x10000>; >>> interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>; >>> clocks = <&clk IMX8MP_CLK_DUMMY>, >>> @@ -783,7 +783,7 @@ usdhc1: mmc@30b40000 { >>> }; >>> >>> usdhc2: mmc@30b50000 { >>> - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; >>> + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; >>> reg = <0x30b50000 0x10000>; >>> interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH>; >>> clocks = <&clk IMX8MP_CLK_DUMMY>, >>> @@ -797,7 +797,7 @@ usdhc2: mmc@30b50000 { >>> }; >>> >>> usdhc3: mmc@30b60000 { >>> - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; >>> + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; >>> reg = <0x30b60000 0x10000>; >>> interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>; >>> clocks = <&clk IMX8MP_CLK_DUMMY>, >> >> >> -- >> Pengutronix e.K. | | >> Steuerwalder Str. 21 | http://www.pengutronix.de/ | >> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | >> Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | >
On 28/03/2022 13:09, Ahmad Fatoum wrote: > Hello Adam, > > On 28.03.22 12:47, Adam Ford wrote: >> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>> >>> Hello Adam, >>> >>> On 27.03.22 14:38, Adam Ford wrote: >>>> The SDHC controller in the imx8mp has the same controller >>>> as the imx8mm which supports HS400-ES. Change the compatible >>>> fallback to imx8mm to enable it. >>> >>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>> >>> I find dropping compatibles problematic, because like Linux matching >>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>> >>> I'd prefer that either the kernel driver gains extra compatibles or that >>> the DTS lists extra compatibles and we refrain from dropping existing >>> (correct) ones. >>> >> >> I would argue that imx7d is not correct since the IP blocks between >> imx7d and imx8mm have different flags/quirks. One of which includes >> HS400-ES, but there are other differences as well. > > The DTS currently says that an fsl,imx7d-usdhc is a subset of an > fsl,imx8mm-usdhc. So a driver could treat both HW the exact same > by focusing on the i.MX7D parts. Linux apparently did exactly > that so far. Is this not accurate? > > >>> What do you think? >> >> From my understanding of the fallback compatibility strings is to >> avoid having to add more and more compatible strings to the drivers >> when they do not serve a functional purpose. Based On a conversation >> with Krzysztof [1], he suggested we update the YAML file based on the >> fallback, but he wanted NXP to give their feedback as to what the >> right fallback strings should be. Haibo from NXP sent me a hierarchy >> [1] which is what I used to update the YAML file. Based on the YAML >> file, the fallback in each DTSI file was updated to ensure the use of >> the proper IP block. > > Myself I am in favor of moving to three compatibles instead of dropping one. > For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same > as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, > but for existing device trees, this may introduce needless potential breakage > for other software that also uses Linux device trees. > Affecting existing users is indeed a concern with this approach, because in-kernel DTS might be used in other projects as well. I still cannot find here the answer whether fsl,imx8mm-usdhc is actually compatible with fsl,imx7d-usdhc. It's not about driver, but about hardware and programming model. imx8mm can support additional features and still be compatible with imx7d. However if any flags of imx7d are actually not valid for imx8mm, then it's different case. Best regards, Krzysztof
On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: > > On 28/03/2022 13:09, Ahmad Fatoum wrote: > > Hello Adam, > > > > On 28.03.22 12:47, Adam Ford wrote: > >> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: > >>> > >>> Hello Adam, > >>> > >>> On 27.03.22 14:38, Adam Ford wrote: > >>>> The SDHC controller in the imx8mp has the same controller > >>>> as the imx8mm which supports HS400-ES. Change the compatible > >>>> fallback to imx8mm to enable it. > >>> > >>> I believe that's a shortcoming of the Linux driver, which should explicitly list > >>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. > >>> > >>> I find dropping compatibles problematic, because like Linux matching > >>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match > >>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. > >>> > >>> I'd prefer that either the kernel driver gains extra compatibles or that > >>> the DTS lists extra compatibles and we refrain from dropping existing > >>> (correct) ones. > >>> > >> > >> I would argue that imx7d is not correct since the IP blocks between > >> imx7d and imx8mm have different flags/quirks. One of which includes > >> HS400-ES, but there are other differences as well. > > > > The DTS currently says that an fsl,imx7d-usdhc is a subset of an > > fsl,imx8mm-usdhc. So a driver could treat both HW the exact same > > by focusing on the i.MX7D parts. Linux apparently did exactly > > that so far. Is this not accurate? > > > > > >>> What do you think? > >> > >> From my understanding of the fallback compatibility strings is to > >> avoid having to add more and more compatible strings to the drivers > >> when they do not serve a functional purpose. Based On a conversation > >> with Krzysztof [1], he suggested we update the YAML file based on the > >> fallback, but he wanted NXP to give their feedback as to what the > >> right fallback strings should be. Haibo from NXP sent me a hierarchy > >> [1] which is what I used to update the YAML file. Based on the YAML > >> file, the fallback in each DTSI file was updated to ensure the use of > >> the proper IP block. > > > > Myself I am in favor of moving to three compatibles instead of dropping one. > > For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same > > as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, > > but for existing device trees, this may introduce needless potential breakage > > for other software that also uses Linux device trees. > > > > Affecting existing users is indeed a concern with this approach, because > in-kernel DTS might be used in other projects as well. > > I still cannot find here the answer whether fsl,imx8mm-usdhc is actually > compatible with fsl,imx7d-usdhc. It's not about driver, but about > hardware and programming model. imx8mm can support additional features > and still be compatible with imx7d. However if any flags of imx7d are > actually not valid for imx8mm, then it's different case. The imx7d flags are: ESDHC_FLAG_USDHC ESDHC_FLAG_STD_TUNING ESDHC_FLAG_HAVE_CAP1 ESDHC_FLAG_HS200 ESDHC_FLAG_HS400 ESDHC_FLAG_STATE_LOST_IN_LPMODE ESDHC_FLAG_BROKEN_AUTO_CMD23, The imx8mm flags are: ESDHC_FLAG_USDHC ESDHC_FLAG_STD_TUNING ESDHC_FLAG_HAVE_CAP1 ESDHC_FLAG_HS200 ESDHC_FLAG_HS400 ESDHC_FLAG_HS400_ES ESDHC_FLAG_STATE_LOST_IN_LPMODE It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] I will defer to Krzysztof and Haibo as to the proper method that we should add HS400-ES. I don't have an issue adding the imx8mn or imx8mp compatible flags to the esdhc driver if that's the decision. If that is the decision, my follow-up question would be how the YAML should look, and if it needs to change at all. adam > > > Best regards, > Krzysztof
On 28/03/2022 14:45, Adam Ford wrote: > On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >> >> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>> Hello Adam, >>> >>> On 28.03.22 12:47, Adam Ford wrote: >>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>> >>>>> Hello Adam, >>>>> >>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>> The SDHC controller in the imx8mp has the same controller >>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>> fallback to imx8mm to enable it. >>>>> >>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>> >>>>> I find dropping compatibles problematic, because like Linux matching >>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>> >>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>> (correct) ones. >>>>> >>>> >>>> I would argue that imx7d is not correct since the IP blocks between >>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>> HS400-ES, but there are other differences as well. >>> >>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>> by focusing on the i.MX7D parts. Linux apparently did exactly >>> that so far. Is this not accurate? >>> >>> >>>>> What do you think? >>>> >>>> From my understanding of the fallback compatibility strings is to >>>> avoid having to add more and more compatible strings to the drivers >>>> when they do not serve a functional purpose. Based On a conversation >>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>> fallback, but he wanted NXP to give their feedback as to what the >>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>> [1] which is what I used to update the YAML file. Based on the YAML >>>> file, the fallback in each DTSI file was updated to ensure the use of >>>> the proper IP block. >>> >>> Myself I am in favor of moving to three compatibles instead of dropping one. >>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>> but for existing device trees, this may introduce needless potential breakage >>> for other software that also uses Linux device trees. >>> >> >> Affecting existing users is indeed a concern with this approach, because >> in-kernel DTS might be used in other projects as well. >> >> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >> compatible with fsl,imx7d-usdhc. It's not about driver, but about >> hardware and programming model. imx8mm can support additional features >> and still be compatible with imx7d. However if any flags of imx7d are >> actually not valid for imx8mm, then it's different case. > > The imx7d flags are: > ESDHC_FLAG_USDHC > ESDHC_FLAG_STD_TUNING > ESDHC_FLAG_HAVE_CAP1 > ESDHC_FLAG_HS200 > ESDHC_FLAG_HS400 > ESDHC_FLAG_STATE_LOST_IN_LPMODE > ESDHC_FLAG_BROKEN_AUTO_CMD23, > > The imx8mm flags are: > ESDHC_FLAG_USDHC > ESDHC_FLAG_STD_TUNING > ESDHC_FLAG_HAVE_CAP1 > ESDHC_FLAG_HS200 > ESDHC_FLAG_HS400 > ESDHC_FLAG_HS400_ES > ESDHC_FLAG_STATE_LOST_IN_LPMODE > > It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. AFAIU, it looks imx8mm is compatible with imx7d, because the broken acmd23 only limits the features. If imx8mm binds according to imx7d, it will not support acmd23 and HS400-ES. Having three compatibles is therefore also OK. You could also add two cases: 1. three compatibles, deprecated: True, 2. two compatibles, without imx7d. Existing DTS stays with three compatibles for two years and later gets converted to two compatibles. New DTS should use two compatibles. It's quite a lot of churn, but would make in the long term bindings correct and also not break other users/projects. > > Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] > > I will defer to Krzysztof and Haibo as to the proper method that we > should add HS400-ES. I don't have an issue adding the imx8mn or > imx8mp compatible flags to the esdhc driver if that's the decision. I don't get what's the problem with HS400-ES. In any case (your patch here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. Best regards, Krzysztof
On Mon, Mar 28, 2022 at 7:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: > > On 28/03/2022 14:45, Adam Ford wrote: > > On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: > >> > >> On 28/03/2022 13:09, Ahmad Fatoum wrote: > >>> Hello Adam, > >>> > >>> On 28.03.22 12:47, Adam Ford wrote: > >>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: > >>>>> > >>>>> Hello Adam, > >>>>> > >>>>> On 27.03.22 14:38, Adam Ford wrote: > >>>>>> The SDHC controller in the imx8mp has the same controller > >>>>>> as the imx8mm which supports HS400-ES. Change the compatible > >>>>>> fallback to imx8mm to enable it. > >>>>> > >>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list > >>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. > >>>>> > >>>>> I find dropping compatibles problematic, because like Linux matching > >>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match > >>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. > >>>>> > >>>>> I'd prefer that either the kernel driver gains extra compatibles or that > >>>>> the DTS lists extra compatibles and we refrain from dropping existing > >>>>> (correct) ones. > >>>>> > >>>> > >>>> I would argue that imx7d is not correct since the IP blocks between > >>>> imx7d and imx8mm have different flags/quirks. One of which includes > >>>> HS400-ES, but there are other differences as well. > >>> > >>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an > >>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same > >>> by focusing on the i.MX7D parts. Linux apparently did exactly > >>> that so far. Is this not accurate? > >>> > >>> > >>>>> What do you think? > >>>> > >>>> From my understanding of the fallback compatibility strings is to > >>>> avoid having to add more and more compatible strings to the drivers > >>>> when they do not serve a functional purpose. Based On a conversation > >>>> with Krzysztof [1], he suggested we update the YAML file based on the > >>>> fallback, but he wanted NXP to give their feedback as to what the > >>>> right fallback strings should be. Haibo from NXP sent me a hierarchy > >>>> [1] which is what I used to update the YAML file. Based on the YAML > >>>> file, the fallback in each DTSI file was updated to ensure the use of > >>>> the proper IP block. > >>> > >>> Myself I am in favor of moving to three compatibles instead of dropping one. > >>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same > >>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, > >>> but for existing device trees, this may introduce needless potential breakage > >>> for other software that also uses Linux device trees. > >>> > >> > >> Affecting existing users is indeed a concern with this approach, because > >> in-kernel DTS might be used in other projects as well. > >> > >> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually > >> compatible with fsl,imx7d-usdhc. It's not about driver, but about > >> hardware and programming model. imx8mm can support additional features > >> and still be compatible with imx7d. However if any flags of imx7d are > >> actually not valid for imx8mm, then it's different case. > > > > The imx7d flags are: > > ESDHC_FLAG_USDHC > > ESDHC_FLAG_STD_TUNING > > ESDHC_FLAG_HAVE_CAP1 > > ESDHC_FLAG_HS200 > > ESDHC_FLAG_HS400 > > ESDHC_FLAG_STATE_LOST_IN_LPMODE > > ESDHC_FLAG_BROKEN_AUTO_CMD23, > > > > The imx8mm flags are: > > ESDHC_FLAG_USDHC > > ESDHC_FLAG_STD_TUNING > > ESDHC_FLAG_HAVE_CAP1 > > ESDHC_FLAG_HS200 > > ESDHC_FLAG_HS400 > > ESDHC_FLAG_HS400_ES > > ESDHC_FLAG_STATE_LOST_IN_LPMODE > > > > It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. > > AFAIU, it looks imx8mm is compatible with imx7d, because the broken > acmd23 only limits the features. If imx8mm binds according to imx7d, it > will not support acmd23 and HS400-ES. > > Having three compatibles is therefore also OK. > > You could also add two cases: > 1. three compatibles, deprecated: True, > 2. two compatibles, without imx7d. > > Existing DTS stays with three compatibles for two years and later gets > converted to two compatibles. New DTS should use two compatibles. > > It's quite a lot of churn, but would make in the long term bindings > correct and also not break other users/projects. > > > > > Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] > > > > I will defer to Krzysztof and Haibo as to the proper method that we > > should add HS400-ES. I don't have an issue adding the imx8mn or > > imx8mp compatible flags to the esdhc driver if that's the decision. > > I don't get what's the problem with HS400-ES. In any case (your patch > here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. I was under the impression Ahmad didn't want me to add the imx8mm compatible to the DTS, but instead, add the imx8mp compatible into the driver so it binds directly to an imx8mp. Based on that, I was assuming this patch series would be rejected and I sould focus on just the driver file itself From what I am reading from you, I should make the imx8mn and imx8mp device trees respectively read: compatible = "fsl,imx8mn-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; and compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; If that's true, do I need to change the YAML at all? adam > > Best regards, > Krzysztof
Hello Krzysztof, On 28.03.22 14:56, Krzysztof Kozlowski wrote: > On 28/03/2022 14:45, Adam Ford wrote: >> On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>> >>> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>>> Hello Adam, >>>> >>>> On 28.03.22 12:47, Adam Ford wrote: >>>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>>> >>>>>> Hello Adam, >>>>>> >>>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>>> The SDHC controller in the imx8mp has the same controller >>>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>>> fallback to imx8mm to enable it. >>>>>> >>>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>>> >>>>>> I find dropping compatibles problematic, because like Linux matching >>>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>>> >>>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>>> (correct) ones. >>>>>> >>>>> >>>>> I would argue that imx7d is not correct since the IP blocks between >>>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>>> HS400-ES, but there are other differences as well. >>>> >>>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>>> by focusing on the i.MX7D parts. Linux apparently did exactly >>>> that so far. Is this not accurate? >>>> >>>> >>>>>> What do you think? >>>>> >>>>> From my understanding of the fallback compatibility strings is to >>>>> avoid having to add more and more compatible strings to the drivers >>>>> when they do not serve a functional purpose. Based On a conversation >>>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>>> fallback, but he wanted NXP to give their feedback as to what the >>>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>>> [1] which is what I used to update the YAML file. Based on the YAML >>>>> file, the fallback in each DTSI file was updated to ensure the use of >>>>> the proper IP block. >>>> >>>> Myself I am in favor of moving to three compatibles instead of dropping one. >>>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>>> but for existing device trees, this may introduce needless potential breakage >>>> for other software that also uses Linux device trees. >>>> >>> >>> Affecting existing users is indeed a concern with this approach, because >>> in-kernel DTS might be used in other projects as well. >>> >>> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >>> compatible with fsl,imx7d-usdhc. It's not about driver, but about >>> hardware and programming model. imx8mm can support additional features >>> and still be compatible with imx7d. However if any flags of imx7d are >>> actually not valid for imx8mm, then it's different case. >> >> The imx7d flags are: >> ESDHC_FLAG_USDHC >> ESDHC_FLAG_STD_TUNING >> ESDHC_FLAG_HAVE_CAP1 >> ESDHC_FLAG_HS200 >> ESDHC_FLAG_HS400 >> ESDHC_FLAG_STATE_LOST_IN_LPMODE >> ESDHC_FLAG_BROKEN_AUTO_CMD23, >> >> The imx8mm flags are: >> ESDHC_FLAG_USDHC >> ESDHC_FLAG_STD_TUNING >> ESDHC_FLAG_HAVE_CAP1 >> ESDHC_FLAG_HS200 >> ESDHC_FLAG_HS400 >> ESDHC_FLAG_HS400_ES >> ESDHC_FLAG_STATE_LOST_IN_LPMODE >> >> It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. > > AFAIU, it looks imx8mm is compatible with imx7d, because the broken > acmd23 only limits the features. If imx8mm binds according to imx7d, it > will not support acmd23 and HS400-ES. > > Having three compatibles is therefore also OK. My thoughts, exactly. > You could also add two cases: > 1. three compatibles, deprecated: True, > 2. two compatibles, without imx7d. > > Existing DTS stays with three compatibles for two years and later gets > converted to two compatibles. New DTS should use two compatibles. > > It's quite a lot of churn, but would make in the long term bindings > correct and also not break other users/projects. I don't see why we need to deprecate the old binding. New SoCs can be imx8mm-usdhc compatible from the beginning and need not care about the old binding. Existing SoCs can just remain imx7d-usdhc compatible as they are now. I don't see what the deprecation accomplishes. >> Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] >> >> I will defer to Krzysztof and Haibo as to the proper method that we >> should add HS400-ES. I don't have an issue adding the imx8mn or >> imx8mp compatible flags to the esdhc driver if that's the decision. > > I don't get what's the problem with HS400-ES. In any case (your patch > here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. Cheers, Ahmad > Best regards, > Krzysztof
Hello Adam, On 28.03.22 15:06, Adam Ford wrote: > On Mon, Mar 28, 2022 at 7:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >> >> On 28/03/2022 14:45, Adam Ford wrote: >>> On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>>> >>>> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>>>> Hello Adam, >>>>> >>>>> On 28.03.22 12:47, Adam Ford wrote: >>>>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>>>> >>>>>>> Hello Adam, >>>>>>> >>>>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>>>> The SDHC controller in the imx8mp has the same controller >>>>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>>>> fallback to imx8mm to enable it. >>>>>>> >>>>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>>>> >>>>>>> I find dropping compatibles problematic, because like Linux matching >>>>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>>>> >>>>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>>>> (correct) ones. >>>>>>> >>>>>> >>>>>> I would argue that imx7d is not correct since the IP blocks between >>>>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>>>> HS400-ES, but there are other differences as well. >>>>> >>>>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>>>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>>>> by focusing on the i.MX7D parts. Linux apparently did exactly >>>>> that so far. Is this not accurate? >>>>> >>>>> >>>>>>> What do you think? >>>>>> >>>>>> From my understanding of the fallback compatibility strings is to >>>>>> avoid having to add more and more compatible strings to the drivers >>>>>> when they do not serve a functional purpose. Based On a conversation >>>>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>>>> fallback, but he wanted NXP to give their feedback as to what the >>>>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>>>> [1] which is what I used to update the YAML file. Based on the YAML >>>>>> file, the fallback in each DTSI file was updated to ensure the use of >>>>>> the proper IP block. >>>>> >>>>> Myself I am in favor of moving to three compatibles instead of dropping one. >>>>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>>>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>>>> but for existing device trees, this may introduce needless potential breakage >>>>> for other software that also uses Linux device trees. >>>>> >>>> >>>> Affecting existing users is indeed a concern with this approach, because >>>> in-kernel DTS might be used in other projects as well. >>>> >>>> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >>>> compatible with fsl,imx7d-usdhc. It's not about driver, but about >>>> hardware and programming model. imx8mm can support additional features >>>> and still be compatible with imx7d. However if any flags of imx7d are >>>> actually not valid for imx8mm, then it's different case. >>> >>> The imx7d flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> ESDHC_FLAG_BROKEN_AUTO_CMD23, >>> >>> The imx8mm flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_HS400_ES >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> >>> It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. >> >> AFAIU, it looks imx8mm is compatible with imx7d, because the broken >> acmd23 only limits the features. If imx8mm binds according to imx7d, it >> will not support acmd23 and HS400-ES. >> >> Having three compatibles is therefore also OK. >> >> You could also add two cases: >> 1. three compatibles, deprecated: True, >> 2. two compatibles, without imx7d. >> >> Existing DTS stays with three compatibles for two years and later gets >> converted to two compatibles. New DTS should use two compatibles. >> >> It's quite a lot of churn, but would make in the long term bindings >> correct and also not break other users/projects. >> >>> >>> Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] >>> >>> I will defer to Krzysztof and Haibo as to the proper method that we >>> should add HS400-ES. I don't have an issue adding the imx8mn or >>> imx8mp compatible flags to the esdhc driver if that's the decision. >> >> I don't get what's the problem with HS400-ES. In any case (your patch >> here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. > > I was under the impression Ahmad didn't want me to add the imx8mm > compatible to the DTS, but instead, add the imx8mp compatible into the > driver so it binds directly to an imx8mp. > Based on that, I was assuming this patch series would be rejected and > I sould focus on just the driver file itself My objection is about dropping the compatible. I am fine with either: - adding fsl,imx8mm-usdhc as an additional compatible - extending the Linux driver I am myself unsure, which is the preferred way, but both resolve your issue, while not breaking other so far valid uses. Cheers, Ahmad > From what I am reading from you, I should make the imx8mn and imx8mp > device trees respectively read: > > compatible = "fsl,imx8mn-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; > > and > > compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; > > If that's true, do I need to change the YAML at all? > > adam >> >> Best regards, >> Krzysztof >
On 28/03/2022 15:07, Ahmad Fatoum wrote: > Hello Krzysztof, > > On 28.03.22 14:56, Krzysztof Kozlowski wrote: >> On 28/03/2022 14:45, Adam Ford wrote: >>> On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>>> >>>> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>>>> Hello Adam, >>>>> >>>>> On 28.03.22 12:47, Adam Ford wrote: >>>>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>>>> >>>>>>> Hello Adam, >>>>>>> >>>>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>>>> The SDHC controller in the imx8mp has the same controller >>>>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>>>> fallback to imx8mm to enable it. >>>>>>> >>>>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>>>> >>>>>>> I find dropping compatibles problematic, because like Linux matching >>>>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>>>> >>>>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>>>> (correct) ones. >>>>>>> >>>>>> >>>>>> I would argue that imx7d is not correct since the IP blocks between >>>>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>>>> HS400-ES, but there are other differences as well. >>>>> >>>>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>>>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>>>> by focusing on the i.MX7D parts. Linux apparently did exactly >>>>> that so far. Is this not accurate? >>>>> >>>>> >>>>>>> What do you think? >>>>>> >>>>>> From my understanding of the fallback compatibility strings is to >>>>>> avoid having to add more and more compatible strings to the drivers >>>>>> when they do not serve a functional purpose. Based On a conversation >>>>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>>>> fallback, but he wanted NXP to give their feedback as to what the >>>>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>>>> [1] which is what I used to update the YAML file. Based on the YAML >>>>>> file, the fallback in each DTSI file was updated to ensure the use of >>>>>> the proper IP block. >>>>> >>>>> Myself I am in favor of moving to three compatibles instead of dropping one. >>>>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>>>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>>>> but for existing device trees, this may introduce needless potential breakage >>>>> for other software that also uses Linux device trees. >>>>> >>>> >>>> Affecting existing users is indeed a concern with this approach, because >>>> in-kernel DTS might be used in other projects as well. >>>> >>>> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >>>> compatible with fsl,imx7d-usdhc. It's not about driver, but about >>>> hardware and programming model. imx8mm can support additional features >>>> and still be compatible with imx7d. However if any flags of imx7d are >>>> actually not valid for imx8mm, then it's different case. >>> >>> The imx7d flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> ESDHC_FLAG_BROKEN_AUTO_CMD23, >>> >>> The imx8mm flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_HS400_ES >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> >>> It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. >> >> AFAIU, it looks imx8mm is compatible with imx7d, because the broken >> acmd23 only limits the features. If imx8mm binds according to imx7d, it >> will not support acmd23 and HS400-ES. >> >> Having three compatibles is therefore also OK. > > My thoughts, exactly. > >> You could also add two cases: >> 1. three compatibles, deprecated: True, >> 2. two compatibles, without imx7d. >> >> Existing DTS stays with three compatibles for two years and later gets >> converted to two compatibles. New DTS should use two compatibles. >> >> It's quite a lot of churn, but would make in the long term bindings >> correct and also not break other users/projects. > > I don't see why we need to deprecate the old binding. New SoCs > can be imx8mm-usdhc compatible from the beginning and need not > care about the old binding. Existing SoCs can just remain imx7d-usdhc > compatible as they are now. > > I don't see what the deprecation accomplishes. It avoids to have too many entries of imx8mm (imx8mm alone, imx8mm+imx7d, imx8xx+imx8mm+imx7d). Best regards, Krzysztof
On 28/03/2022 15:12, Ahmad Fatoum wrote: > Hello Adam, > > On 28.03.22 15:06, Adam Ford wrote: >> On Mon, Mar 28, 2022 at 7:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>> >>> On 28/03/2022 14:45, Adam Ford wrote: >>>> On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>>>> >>>>> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>>>>> Hello Adam, >>>>>> >>>>>> On 28.03.22 12:47, Adam Ford wrote: >>>>>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>>>>> >>>>>>>> Hello Adam, >>>>>>>> >>>>>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>>>>> The SDHC controller in the imx8mp has the same controller >>>>>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>>>>> fallback to imx8mm to enable it. >>>>>>>> >>>>>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>>>>> >>>>>>>> I find dropping compatibles problematic, because like Linux matching >>>>>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>>>>> >>>>>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>>>>> (correct) ones. >>>>>>>> >>>>>>> >>>>>>> I would argue that imx7d is not correct since the IP blocks between >>>>>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>>>>> HS400-ES, but there are other differences as well. >>>>>> >>>>>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>>>>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>>>>> by focusing on the i.MX7D parts. Linux apparently did exactly >>>>>> that so far. Is this not accurate? >>>>>> >>>>>> >>>>>>>> What do you think? >>>>>>> >>>>>>> From my understanding of the fallback compatibility strings is to >>>>>>> avoid having to add more and more compatible strings to the drivers >>>>>>> when they do not serve a functional purpose. Based On a conversation >>>>>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>>>>> fallback, but he wanted NXP to give their feedback as to what the >>>>>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>>>>> [1] which is what I used to update the YAML file. Based on the YAML >>>>>>> file, the fallback in each DTSI file was updated to ensure the use of >>>>>>> the proper IP block. >>>>>> >>>>>> Myself I am in favor of moving to three compatibles instead of dropping one. >>>>>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>>>>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>>>>> but for existing device trees, this may introduce needless potential breakage >>>>>> for other software that also uses Linux device trees. >>>>>> >>>>> >>>>> Affecting existing users is indeed a concern with this approach, because >>>>> in-kernel DTS might be used in other projects as well. >>>>> >>>>> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >>>>> compatible with fsl,imx7d-usdhc. It's not about driver, but about >>>>> hardware and programming model. imx8mm can support additional features >>>>> and still be compatible with imx7d. However if any flags of imx7d are >>>>> actually not valid for imx8mm, then it's different case. >>>> >>>> The imx7d flags are: >>>> ESDHC_FLAG_USDHC >>>> ESDHC_FLAG_STD_TUNING >>>> ESDHC_FLAG_HAVE_CAP1 >>>> ESDHC_FLAG_HS200 >>>> ESDHC_FLAG_HS400 >>>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>>> ESDHC_FLAG_BROKEN_AUTO_CMD23, >>>> >>>> The imx8mm flags are: >>>> ESDHC_FLAG_USDHC >>>> ESDHC_FLAG_STD_TUNING >>>> ESDHC_FLAG_HAVE_CAP1 >>>> ESDHC_FLAG_HS200 >>>> ESDHC_FLAG_HS400 >>>> ESDHC_FLAG_HS400_ES >>>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>>> >>>> It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. >>> >>> AFAIU, it looks imx8mm is compatible with imx7d, because the broken >>> acmd23 only limits the features. If imx8mm binds according to imx7d, it >>> will not support acmd23 and HS400-ES. >>> >>> Having three compatibles is therefore also OK. >>> >>> You could also add two cases: >>> 1. three compatibles, deprecated: True, >>> 2. two compatibles, without imx7d. >>> >>> Existing DTS stays with three compatibles for two years and later gets >>> converted to two compatibles. New DTS should use two compatibles. >>> >>> It's quite a lot of churn, but would make in the long term bindings >>> correct and also not break other users/projects. >>> >>>> >>>> Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] >>>> >>>> I will defer to Krzysztof and Haibo as to the proper method that we >>>> should add HS400-ES. I don't have an issue adding the imx8mn or >>>> imx8mp compatible flags to the esdhc driver if that's the decision. >>> >>> I don't get what's the problem with HS400-ES. In any case (your patch >>> here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. >> >> I was under the impression Ahmad didn't want me to add the imx8mm >> compatible to the DTS, but instead, add the imx8mp compatible into the >> driver so it binds directly to an imx8mp. It's not really related the bindings, so don't ask me. Best regards, Krzysztof
On 28/03/2022 15:06, Adam Ford wrote: > On Mon, Mar 28, 2022 at 7:56 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >> >> On 28/03/2022 14:45, Adam Ford wrote: >>> On Mon, Mar 28, 2022 at 6:49 AM Krzysztof Kozlowski <krzk@kernel.org> wrote: >>>> >>>> On 28/03/2022 13:09, Ahmad Fatoum wrote: >>>>> Hello Adam, >>>>> >>>>> On 28.03.22 12:47, Adam Ford wrote: >>>>>> On Mon, Mar 28, 2022 at 2:20 AM Ahmad Fatoum <a.fatoum@pengutronix.de> wrote: >>>>>>> >>>>>>> Hello Adam, >>>>>>> >>>>>>> On 27.03.22 14:38, Adam Ford wrote: >>>>>>>> The SDHC controller in the imx8mp has the same controller >>>>>>>> as the imx8mm which supports HS400-ES. Change the compatible >>>>>>>> fallback to imx8mm to enable it. >>>>>>> >>>>>>> I believe that's a shortcoming of the Linux driver, which should explicitly list >>>>>>> fsl,imx8mp-usdhc in its compatibles and enable HS400-ES for it. >>>>>>> >>>>>>> I find dropping compatibles problematic, because like Linux matching >>>>>>> fsl,imx8mm-usdhc, but not fsl,imx8mp-usdhc, other software may match >>>>>>> fsl,imx7d-usdhc, but not fsl,imx8[mp]-usdhc. >>>>>>> >>>>>>> I'd prefer that either the kernel driver gains extra compatibles or that >>>>>>> the DTS lists extra compatibles and we refrain from dropping existing >>>>>>> (correct) ones. >>>>>>> >>>>>> >>>>>> I would argue that imx7d is not correct since the IP blocks between >>>>>> imx7d and imx8mm have different flags/quirks. One of which includes >>>>>> HS400-ES, but there are other differences as well. >>>>> >>>>> The DTS currently says that an fsl,imx7d-usdhc is a subset of an >>>>> fsl,imx8mm-usdhc. So a driver could treat both HW the exact same >>>>> by focusing on the i.MX7D parts. Linux apparently did exactly >>>>> that so far. Is this not accurate? >>>>> >>>>> >>>>>>> What do you think? >>>>>> >>>>>> From my understanding of the fallback compatibility strings is to >>>>>> avoid having to add more and more compatible strings to the drivers >>>>>> when they do not serve a functional purpose. Based On a conversation >>>>>> with Krzysztof [1], he suggested we update the YAML file based on the >>>>>> fallback, but he wanted NXP to give their feedback as to what the >>>>>> right fallback strings should be. Haibo from NXP sent me a hierarchy >>>>>> [1] which is what I used to update the YAML file. Based on the YAML >>>>>> file, the fallback in each DTSI file was updated to ensure the use of >>>>>> the proper IP block. >>>>> >>>>> Myself I am in favor of moving to three compatibles instead of dropping one. >>>>> For some theoretical fsl,imx8mf-usdhc that's supposed to be exactly the same >>>>> as a fsl,imx8mm-usdhc, I don't mind omitting the fsl,imx7d-usdhc compatible, >>>>> but for existing device trees, this may introduce needless potential breakage >>>>> for other software that also uses Linux device trees. >>>>> >>>> >>>> Affecting existing users is indeed a concern with this approach, because >>>> in-kernel DTS might be used in other projects as well. >>>> >>>> I still cannot find here the answer whether fsl,imx8mm-usdhc is actually >>>> compatible with fsl,imx7d-usdhc. It's not about driver, but about >>>> hardware and programming model. imx8mm can support additional features >>>> and still be compatible with imx7d. However if any flags of imx7d are >>>> actually not valid for imx8mm, then it's different case. >>> >>> The imx7d flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> ESDHC_FLAG_BROKEN_AUTO_CMD23, >>> >>> The imx8mm flags are: >>> ESDHC_FLAG_USDHC >>> ESDHC_FLAG_STD_TUNING >>> ESDHC_FLAG_HAVE_CAP1 >>> ESDHC_FLAG_HS200 >>> ESDHC_FLAG_HS400 >>> ESDHC_FLAG_HS400_ES >>> ESDHC_FLAG_STATE_LOST_IN_LPMODE >>> >>> It does not have the ESDHC_FLAG_BROKEN_AUTO_CMD23 that is present in the imx7d. >> >> AFAIU, it looks imx8mm is compatible with imx7d, because the broken >> acmd23 only limits the features. If imx8mm binds according to imx7d, it >> will not support acmd23 and HS400-ES. >> >> Having three compatibles is therefore also OK. >> >> You could also add two cases: >> 1. three compatibles, deprecated: True, >> 2. two compatibles, without imx7d. >> >> Existing DTS stays with three compatibles for two years and later gets >> converted to two compatibles. New DTS should use two compatibles. >> >> It's quite a lot of churn, but would make in the long term bindings >> correct and also not break other users/projects. >> >>> >>> Maybe Haibo can comment on whether or not that would be an issue for the 8m[mnp] >>> >>> I will defer to Krzysztof and Haibo as to the proper method that we >>> should add HS400-ES. I don't have an issue adding the imx8mn or >>> imx8mp compatible flags to the esdhc driver if that's the decision. >> >> I don't get what's the problem with HS400-ES. In any case (your patch >> here, other ideas) your DTS will bind to imx8mm-usdhc which has HS400-ES. > > I was under the impression Ahmad didn't want me to add the imx8mm > compatible to the DTS, but instead, add the imx8mp compatible into the > driver so it binds directly to an imx8mp. > Based on that, I was assuming this patch series would be rejected and > I sould focus on just the driver file itself > > From what I am reading from you, I should make the imx8mn and imx8mp > device trees respectively read: > > compatible = "fsl,imx8mn-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; > > and > > compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc", "fsl,imx7d-usdhc"; > > If that's true, do I need to change the YAML at all? Sorry, I do not remember all the Linux kernel bindings by heart, so you need to check by yourself whether they cover this case or not. Best regards, Krzysztof
On 28.03.22 15:14, Krzysztof Kozlowski wrote: > On 28/03/2022 15:07, Ahmad Fatoum wrote: >> On 28.03.22 14:56, Krzysztof Kozlowski wrote: >>> You could also add two cases: >>> 1. three compatibles, deprecated: True, >>> 2. two compatibles, without imx7d. >>> >>> Existing DTS stays with three compatibles for two years and later gets >>> converted to two compatibles. New DTS should use two compatibles. >>> >>> It's quite a lot of churn, but would make in the long term bindings >>> correct and also not break other users/projects. >> >> I don't see why we need to deprecate the old binding. New SoCs >> can be imx8mm-usdhc compatible from the beginning and need not >> care about the old binding. Existing SoCs can just remain imx7d-usdhc >> compatible as they are now. >> >> I don't see what the deprecation accomplishes. > > It avoids to have too many entries of imx8mm (imx8mm alone, > imx8mm+imx7d, imx8xx+imx8mm+imx7d). I see. I assume use of deprecated binding will be reported on a dtbs_check? If so, the expectation is that downstream projects run dtbs_check on their imported Linux DT repository, see the deprecation warning and extend their drivers to comply with it. Some time later upstream will remove the deprecated binding and adjust the device trees. This works for me. Cheers, Ahmad > > Best regards, > Krzysztof >
On 28/03/2022 15:42, Ahmad Fatoum wrote: > On 28.03.22 15:14, Krzysztof Kozlowski wrote: >> On 28/03/2022 15:07, Ahmad Fatoum wrote: >>> On 28.03.22 14:56, Krzysztof Kozlowski wrote: >>>> You could also add two cases: >>>> 1. three compatibles, deprecated: True, >>>> 2. two compatibles, without imx7d. >>>> >>>> Existing DTS stays with three compatibles for two years and later gets >>>> converted to two compatibles. New DTS should use two compatibles. >>>> >>>> It's quite a lot of churn, but would make in the long term bindings >>>> correct and also not break other users/projects. >>> >>> I don't see why we need to deprecate the old binding. New SoCs >>> can be imx8mm-usdhc compatible from the beginning and need not >>> care about the old binding. Existing SoCs can just remain imx7d-usdhc >>> compatible as they are now. >>> >>> I don't see what the deprecation accomplishes. >> >> It avoids to have too many entries of imx8mm (imx8mm alone, >> imx8mm+imx7d, imx8xx+imx8mm+imx7d). > > I see. I assume use of deprecated binding will be reported on a dtbs_check? Unfortunately no, at least not yet. :-( > If so, the expectation is that downstream projects run dtbs_check on their > imported Linux DT repository, see the deprecation warning and extend > their drivers to comply with it. > > Some time later upstream will remove the deprecated binding and adjust > the device trees. This works for me. > Yes. Plus this gives the notice to downstream projects, to comply with the change of DTS. Best regards, Krzysztof
diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi index 794d75173cf5..d5ee1520f1fe 100644 --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi @@ -769,7 +769,7 @@ i2c6: i2c@30ae0000 { }; usdhc1: mmc@30b40000 { - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; reg = <0x30b40000 0x10000>; interrupts = <GIC_SPI 22 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clk IMX8MP_CLK_DUMMY>, @@ -783,7 +783,7 @@ usdhc1: mmc@30b40000 { }; usdhc2: mmc@30b50000 { - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; reg = <0x30b50000 0x10000>; interrupts = <GIC_SPI 23 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clk IMX8MP_CLK_DUMMY>, @@ -797,7 +797,7 @@ usdhc2: mmc@30b50000 { }; usdhc3: mmc@30b60000 { - compatible = "fsl,imx8mp-usdhc", "fsl,imx7d-usdhc"; + compatible = "fsl,imx8mp-usdhc", "fsl,imx8mm-usdhc"; reg = <0x30b60000 0x10000>; interrupts = <GIC_SPI 24 IRQ_TYPE_LEVEL_HIGH>; clocks = <&clk IMX8MP_CLK_DUMMY>,
The SDHC controller in the imx8mp has the same controller as the imx8mm which supports HS400-ES. Change the compatible fallback to imx8mm to enable it. Signed-off-by: Adam Ford <aford173@gmail.com> --- arch/arm64/boot/dts/freescale/imx8mp.dtsi | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)