| Message ID | db45d0d68957d699f13a0d92f4f84d8ebfd0270e.1491118230.git.guillaume.tucker@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
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On 04/02/2017 09:59 AM, Guillaume Tucker wrote: > The ARM Mali Midgard GPU family is present in a number of SoCs > from many different vendors such as Samsung Exynos and Rockchip. > > Import the device tree bindings documentation from the r16p0 > release of the Mali Midgard GPU kernel driver: > > https://developer.arm.com/-/media/Files/downloads/mali-drivers/kernel/mali-midgard-gpu/TX011-SW-99002-r16p0-00rel0.tgz > > The following optional bindings have been omitted in this initial > version as they are only used in very specific cases: > > * snoop_enable_smc > * snoop_disable_smc > * jm_config > * power_model > * system-coherency > * ipa-model > > The example has been simplified accordingly. > > The compatible string definition has been limited to > "arm,mali-midgard" to avoid checkpatch.pl warnings and to match > what the driver actually expects (as of r16p0 out-of-tree). > > CC: John Reitan <john.reitan@arm.com> > Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com> > --- > .../devicetree/bindings/gpu/arm,mali-midgard.txt | 53 ++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > > diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > new file mode 100644 > index 000000000000..da8fc6d21bbf > --- /dev/null > +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > @@ -0,0 +1,53 @@ > +# > +# (C) COPYRIGHT 2013-2016 ARM Limited. > +# Copyright (C) 2017 Collabora Ltd > +# > +# This program is free software and is provided to you under the terms of the > +# GNU General Public License version 2 as published by the Free Software > +# Foundation, and any use by you of this program is subject to the terms > +# of such GNU licence. > +# Hi Guillaume, This is unnecessary, please remove. > + > + > +ARM Mali Midgard GPU > +==================== > + > +Required properties: > + > +- compatible : Should be "arm,mali-midgard". > +- reg : Physical base address of the device and length of the register area. > +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. > +- interrupt-names : Contains the names of IRQ resources in the order they were > + provided in the interrupts property. Must contain: "JOB, "MMU", "GPU". Please follow the bindings introduced for the utgard family : https://patchwork.kernel.org/patch/9553745/ - an entry for each mali-midgard revision, i.e. "arm,mali-t820" - an entry for each vendor specific wrapping if necessary, i.e. "amlogic,meson-gxm-mali" - low-case for interrupt names > + > +Optional: > + > +- clocks : Phandle to clock for the Mali Midgard device. > +- clock-names : Shall be "clk_mali". > +- mali-supply : Phandle to regulator for the Mali device. Refer to > + Documentation/devicetree/bindings/regulator/regulator.txt for details. > +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt > + for details. Please add : * Must be one of the following: "arm,mali-t820" * And, optionally, one of the vendor specific compatible: "amlogic,meson-gxm-mali" with my Ack for the amlogic platform. > + > +Example for a Mali-T602: > + > +gpu@0xfc010000 { > + compatible = "arm,mali-midgard"; > + reg = <0xfc010000 0x4000>; > + interrupts = <0 36 4>, <0 37 4>, <0 38 4>; > + interrupt-names = "JOB", "MMU", "GPU"; > + > + clocks = <&pclk_mali>; > + clock-names = "clk_mali"; > + mali-supply = <&vdd_mali>; > + operating-points = < > + /* KHz uV */ > + 533000 1250000, > + 450000 1150000, > + 400000 1125000, > + 350000 1075000, > + 266000 1025000, > + 160000 925000, > + 100000 912500, > + >; > +}; > Thanks, Neil
On Sun, Apr 02, 2017 at 08:59:44AM +0100, Guillaume Tucker wrote: > The ARM Mali Midgard GPU family is present in a number of SoCs > from many different vendors such as Samsung Exynos and Rockchip. > > Import the device tree bindings documentation from the r16p0 > release of the Mali Midgard GPU kernel driver: > > https://developer.arm.com/-/media/Files/downloads/mali-drivers/kernel/mali-midgard-gpu/TX011-SW-99002-r16p0-00rel0.tgz > > The following optional bindings have been omitted in this initial > version as they are only used in very specific cases: > > * snoop_enable_smc > * snoop_disable_smc > * jm_config > * power_model > * system-coherency > * ipa-model > > The example has been simplified accordingly. > > The compatible string definition has been limited to > "arm,mali-midgard" to avoid checkpatch.pl warnings and to match > what the driver actually expects (as of r16p0 out-of-tree). > > CC: John Reitan <john.reitan@arm.com> > Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com> > --- > .../devicetree/bindings/gpu/arm,mali-midgard.txt | 53 ++++++++++++++++++++++ > 1 file changed, 53 insertions(+) > create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > > diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > new file mode 100644 > index 000000000000..da8fc6d21bbf > --- /dev/null > +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt > @@ -0,0 +1,53 @@ > +# > +# (C) COPYRIGHT 2013-2016 ARM Limited. > +# Copyright (C) 2017 Collabora Ltd > +# > +# This program is free software and is provided to you under the terms of the > +# GNU General Public License version 2 as published by the Free Software > +# Foundation, and any use by you of this program is subject to the terms > +# of such GNU licence. > +# > + > + > +ARM Mali Midgard GPU > +==================== > + > +Required properties: > + > +- compatible : Should be "arm,mali-midgard". As Neil said... > +- reg : Physical base address of the device and length of the register area. > +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. > +- interrupt-names : Contains the names of IRQ resources in the order they were > + provided in the interrupts property. Must contain: "JOB, "MMU", "GPU". > + > +Optional: > + > +- clocks : Phandle to clock for the Mali Midgard device. > +- clock-names : Shall be "clk_mali". "clk_" is redundant. Actually, if there is only 1 clock, then just drop names. But there's not at least a core and bus clock? > +- mali-supply : Phandle to regulator for the Mali device. Refer to > + Documentation/devicetree/bindings/regulator/regulator.txt for details. > +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt > + for details. Is this going to be sufficient vs. operating-points-v2? Or should it be a power domain with OPPs? > + > +Example for a Mali-T602: > + > +gpu@0xfc010000 { Drop the '0x'. > + compatible = "arm,mali-midgard"; > + reg = <0xfc010000 0x4000>; > + interrupts = <0 36 4>, <0 37 4>, <0 38 4>; > + interrupt-names = "JOB", "MMU", "GPU"; > + > + clocks = <&pclk_mali>; > + clock-names = "clk_mali"; > + mali-supply = <&vdd_mali>; > + operating-points = < > + /* KHz uV */ > + 533000 1250000, > + 450000 1150000, > + 400000 1125000, > + 350000 1075000, > + 266000 1025000, > + 160000 925000, > + 100000 912500, > + >; > +}; > -- > 2.11.0 >
On 03/04/17 09:12, Neil Armstrong wrote: > On 04/02/2017 09:59 AM, Guillaume Tucker wrote: >> The ARM Mali Midgard GPU family is present in a number of SoCs >> from many different vendors such as Samsung Exynos and Rockchip. >> >> Import the device tree bindings documentation from the r16p0 >> release of the Mali Midgard GPU kernel driver: >> >> https://developer.arm.com/-/media/Files/downloads/mali-drivers/kernel/mali-midgard-gpu/TX011-SW-99002-r16p0-00rel0.tgz >> >> The following optional bindings have been omitted in this initial >> version as they are only used in very specific cases: >> >> * snoop_enable_smc >> * snoop_disable_smc >> * jm_config >> * power_model >> * system-coherency >> * ipa-model >> >> The example has been simplified accordingly. >> >> The compatible string definition has been limited to >> "arm,mali-midgard" to avoid checkpatch.pl warnings and to match >> what the driver actually expects (as of r16p0 out-of-tree). >> >> CC: John Reitan <john.reitan@arm.com> >> Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com> >> --- >> .../devicetree/bindings/gpu/arm,mali-midgard.txt | 53 ++++++++++++++++++++++ >> 1 file changed, 53 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> >> diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> new file mode 100644 >> index 000000000000..da8fc6d21bbf >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> @@ -0,0 +1,53 @@ >> +# >> +# (C) COPYRIGHT 2013-2016 ARM Limited. >> +# Copyright (C) 2017 Collabora Ltd >> +# >> +# This program is free software and is provided to you under the terms of the >> +# GNU General Public License version 2 as published by the Free Software >> +# Foundation, and any use by you of this program is subject to the terms >> +# of such GNU licence. >> +# > Hi Guillaume, > This is unnecessary, please remove. Hi Neil, I see most other documentation files don't have such a header, including the arm,mali-utgard.txt one. I left it in my patch after copying the file from the driver tarball as removing it didn't seem right from a GPL and copyright point of view. If it's safe in practice to remove it then fine. >> + >> + >> +ARM Mali Midgard GPU >> +==================== >> + >> +Required properties: >> + >> +- compatible : Should be "arm,mali-midgard". >> +- reg : Physical base address of the device and length of the register area. >> +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. >> +- interrupt-names : Contains the names of IRQ resources in the order they were >> + provided in the interrupts property. Must contain: "JOB, "MMU", "GPU". > > > Please follow the bindings introduced for the utgard family : > https://patchwork.kernel.org/patch/9553745/ > > - an entry for each mali-midgard revision, i.e. "arm,mali-t820" Sure. It's a bit more complicated with Midgard (more variants, some have the number of cores in the last digit...) but it should be possible to put together a suitable list in v3. > - an entry for each vendor specific wrapping if necessary, i.e. "amlogic,meson-gxm-mali" Well, fine although I'm a bit confused about this - please see below. > - low-case for interrupt names OK, can change that in v3. It means however that the out-of-tree driver will need to be patched as it's looking for these names in capital letters. This shouldn't be a big issue but adds a bit of work to anyone maintaining a kernel driver package. >> + >> +Optional: >> + >> +- clocks : Phandle to clock for the Mali Midgard device. >> +- clock-names : Shall be "clk_mali". >> +- mali-supply : Phandle to regulator for the Mali device. Refer to >> + Documentation/devicetree/bindings/regulator/regulator.txt for details. >> +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt >> + for details. > > Please add : > * Must be one of the following: > "arm,mali-t820" > * And, optionally, one of the vendor specific compatible: > "amlogic,meson-gxm-mali" > > with my Ack for the amlogic platform. It seems to me that as long as the GPU architecture hasn't been modified (I don't think I've ever encountered such a case) then it has to be a standard ARM Mali type regardless of the SoC vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the same as a T820 in a different SoC, please forgive me but I don't understand why a vendor compatible string is needed. My main concern is that it's going to be very hard to keep that list up-to-date with all existing Midgard SoC variants. If do we need to add vendor compatible strings to correctly describe the hardware then I'm happy to add the amlogic one in my patch v3; I would just like to understand why that's necessary. Thanks, Guillaume
Hi Guillaume, Am Dienstag, 11. April 2017, 18:40:37 CEST schrieb Guillaume Tucker: > On 03/04/17 09:12, Neil Armstrong wrote: > > On 04/02/2017 09:59 AM, Guillaume Tucker wrote: > >> +Optional: > >> + > >> +- clocks : Phandle to clock for the Mali Midgard device. > >> +- clock-names : Shall be "clk_mali". > >> +- mali-supply : Phandle to regulator for the Mali device. Refer to > >> + Documentation/devicetree/bindings/regulator/regulator.txt for details. > >> +- operating-points : Refer to > >> Documentation/devicetree/bindings/power/opp.txt + for details. > > > > Please add : > > * Must be one of the following: > > "arm,mali-t820" > > > > * And, optionally, one of the vendor specific compatible: > > "amlogic,meson-gxm-mali" > > > > with my Ack for the amlogic platform. > > It seems to me that as long as the GPU architecture hasn't been > modified (I don't think I've ever encountered such a case) then > it has to be a standard ARM Mali type regardless of the SoC > vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the > same as a T820 in a different SoC, please forgive me but I don't > understand why a vendor compatible string is needed. My main > concern is that it's going to be very hard to keep that list > up-to-date with all existing Midgard SoC variants. If do we need > to add vendor compatible strings to correctly describe the > hardware then I'm happy to add the amlogic one in my patch v3; I > would just like to understand why that's necessary. SoC vendors in most cases hook ip blocks into their socs in different and often strange ways. After all it's not some discrete ic you solder onto a board, but instead a part of the soc itself. So in most cases you will have some hooks outside the actual gpu iospace that can be used to tune different things about how the gpu interacts with the system. Which is probably also the reason the midgard kernel driver has this ugly "platform" subdirectory for compile-time platform selection. On my rk3288 for example we have [0] in the chromeos tree, that handles the oddities of the midgard on the rk3288 used in a lot of Chromebooks. There are soc-specific oddities of frequencies, frequency-scaling and whatnot. And there are also more gpu-specific setting in syscon areas of the soc (pmu and grf) that can also influence the gpus performance and might need tweaking at some point. That doesn't even take into account that there may even be differences on how things are synthesized that we don't know about. See all the variants of the dw_hdmi ip block (imx, rockchip, meson [more?]) . So we really want to have the special compatibles in place, to be prepared for the future per-soc oddities that always appear :-) . Heiko [0] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.14/drivers/gpu/arm/midgard/platform/rk/
Hi Heiko, On 11/04/17 21:52, Heiko Stübner wrote: > Hi Guillaume, > > Am Dienstag, 11. April 2017, 18:40:37 CEST schrieb Guillaume Tucker: >> On 03/04/17 09:12, Neil Armstrong wrote: >>> On 04/02/2017 09:59 AM, Guillaume Tucker wrote: >>>> +Optional: >>>> + >>>> +- clocks : Phandle to clock for the Mali Midgard device. >>>> +- clock-names : Shall be "clk_mali". >>>> +- mali-supply : Phandle to regulator for the Mali device. Refer to >>>> + Documentation/devicetree/bindings/regulator/regulator.txt for details. >>>> +- operating-points : Refer to >>>> Documentation/devicetree/bindings/power/opp.txt + for details. >>> >>> Please add : >>> * Must be one of the following: >>> "arm,mali-t820" >>> >>> * And, optionally, one of the vendor specific compatible: >>> "amlogic,meson-gxm-mali" >>> >>> with my Ack for the amlogic platform. >> >> It seems to me that as long as the GPU architecture hasn't been >> modified (I don't think I've ever encountered such a case) then >> it has to be a standard ARM Mali type regardless of the SoC >> vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the >> same as a T820 in a different SoC, please forgive me but I don't >> understand why a vendor compatible string is needed. My main >> concern is that it's going to be very hard to keep that list >> up-to-date with all existing Midgard SoC variants. If do we need >> to add vendor compatible strings to correctly describe the >> hardware then I'm happy to add the amlogic one in my patch v3; I >> would just like to understand why that's necessary. > > SoC vendors in most cases hook ip blocks into their socs in different > and often strange ways. After all it's not some discrete ic you solder > onto a board, but instead a part of the soc itself. Thanks for your explanation. I see, it's really about special things that are not supported by the standard Midgard kernel driver. > So in most cases you will have some hooks outside the actual gpu iospace > that can be used to tune different things about how the gpu interacts with > the system. Which is probably also the reason the midgard kernel driver > has this ugly "platform" subdirectory for compile-time platform selection. I see the "platform" directory approach as an old and deprecated way of supporting platforms, upstreaming the dt bindings goes in the direction of using solely the device tree to describe the GPU hardware (i.e. CONFIG_MALI_PLATFORM_DEVICETREE). If something quirky is needed in the platform, it should be possible to support it outside the GPU driver (platform devfreq etc...). Back to the original intent of enabling distros to make Mali GPU driver packages, when using the device tree you can have a single kernel driver package for all Midgard platforms. When using the third-party platform sources approach, you need to make an extra package for each one of them. So if there is value in supporting platforms that absolutely require something special due to their hardware GPU integration, then yes I see why vendor dt bindings might be useful. However it seems to me that this should really be an exception and avoided whenever possible. > On my rk3288 for example we have [0] in the chromeos tree, that handles > the oddities of the midgard on the rk3288 used in a lot of Chromebooks. > There are soc-specific oddities of frequencies, frequency-scaling and > whatnot. And there are also more gpu-specific setting in syscon areas > of the soc (pmu and grf) that can also influence the gpus performance > and might need tweaking at some point. For the rk3288, this is purely a software implementation issue on the chromeos-3.14 branch. With mainline kernel, you can use devfreq and no platform files at all (that's how I tested these dt bindings). So as far as I know, there's no need for a vendor compatible string on rk3288. > That doesn't even take into account that there may even be differences > on how things are synthesized that we don't know about. See all the > variants of the dw_hdmi ip block (imx, rockchip, meson [more?]) . I'm not too familiar with that driver, just had a quick look and it seems to be a different issue as there's a kernel config for each platform to build separate driver modules. And it looks like they are actually needed to cope with variants of the hardware inside the display processor block, unlike with the Mali GPU which in principle should always be the same. I've run this Midgard driver without any platform files and using devfreq at least on rk3288 Firefly, Exynos 5422 ODROID-XU3 and Juno and they all have a vanilla Mali GPU hw block. It's just wired differently in each SoC. > So we really want to have the special compatibles in place, to be prepared > for the future per-soc oddities that always appear :-) . How about aiming for the ideal case where vendor-specific things are not needed and add them if and when they really become inevitable and worth the cost? Thanks, Guillaume > [0] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.14/drivers/gpu/arm/midgard/platform/rk/
Hi Guillaume, On 04/12/2017 10:25 AM, Guillaume Tucker wrote: > Hi Heiko, > > On 11/04/17 21:52, Heiko Stübner wrote: >> Hi Guillaume, >> >> Am Dienstag, 11. April 2017, 18:40:37 CEST schrieb Guillaume Tucker: >>> On 03/04/17 09:12, Neil Armstrong wrote: >>>> On 04/02/2017 09:59 AM, Guillaume Tucker wrote: >>>>> +Optional: >>>>> + >>>>> +- clocks : Phandle to clock for the Mali Midgard device. >>>>> +- clock-names : Shall be "clk_mali". >>>>> +- mali-supply : Phandle to regulator for the Mali device. Refer to >>>>> + Documentation/devicetree/bindings/regulator/regulator.txt for details. >>>>> +- operating-points : Refer to >>>>> Documentation/devicetree/bindings/power/opp.txt + for details. >>>> >>>> Please add : >>>> * Must be one of the following: >>>> "arm,mali-t820" >>>> >>>> * And, optionally, one of the vendor specific compatible: >>>> "amlogic,meson-gxm-mali" >>>> >>>> with my Ack for the amlogic platform. >>> >>> It seems to me that as long as the GPU architecture hasn't been >>> modified (I don't think I've ever encountered such a case) then >>> it has to be a standard ARM Mali type regardless of the SoC >>> vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the >>> same as a T820 in a different SoC, please forgive me but I don't >>> understand why a vendor compatible string is needed. My main >>> concern is that it's going to be very hard to keep that list >>> up-to-date with all existing Midgard SoC variants. If do we need >>> to add vendor compatible strings to correctly describe the >>> hardware then I'm happy to add the amlogic one in my patch v3; I >>> would just like to understand why that's necessary. >> >> SoC vendors in most cases hook ip blocks into their socs in different >> and often strange ways. After all it's not some discrete ic you solder >> onto a board, but instead a part of the soc itself. > > Thanks for your explanation. I see, it's really about special > things that are not supported by the standard Midgard kernel > driver. > >> So in most cases you will have some hooks outside the actual gpu iospace >> that can be used to tune different things about how the gpu interacts with >> the system. Which is probably also the reason the midgard kernel driver >> has this ugly "platform" subdirectory for compile-time platform selection. > > I see the "platform" directory approach as an old and deprecated > way of supporting platforms, upstreaming the dt bindings goes in > the direction of using solely the device tree to describe the GPU > hardware (i.e. CONFIG_MALI_PLATFORM_DEVICETREE). If something > quirky is needed in the platform, it should be possible to > support it outside the GPU driver (platform devfreq etc...). If this was so simple... This is why the "vendor" compatible is optional. And on another side, the binding were written by ARM, are may not be compatible with how the mainline Linux handles these uses-cases. ARM added some tweaks to handle some weird integration using DT properties, but this should definitely go in platform specific code instead. > > Back to the original intent of enabling distros to make Mali GPU > driver packages, when using the device tree you can have a single > kernel driver package for all Midgard platforms. When using the > third-party platform sources approach, you need to make an extra > package for each one of them. Well, if the midgard driver was maintained in community-driven way, all vendor could actually push their platform code, but it's not the case and somehow never will. > > So if there is value in supporting platforms that absolutely > require something special due to their hardware GPU integration, > then yes I see why vendor dt bindings might be useful. However > it seems to me that this should really be an exception and > avoided whenever possible. I understand you would avoid changing the (horrible) way the midgard driver handles the DT... But ultimately, if we consider the eventual integration of the midgard driver in mainline kernel (because why not ?), the driver would need a complete re-write to conform the actual driver coding structure, and so would also need to conform to the DT mainline rules. > >> On my rk3288 for example we have [0] in the chromeos tree, that handles >> the oddities of the midgard on the rk3288 used in a lot of Chromebooks. >> There are soc-specific oddities of frequencies, frequency-scaling and >> whatnot. And there are also more gpu-specific setting in syscon areas >> of the soc (pmu and grf) that can also influence the gpus performance >> and might need tweaking at some point. > > For the rk3288, this is purely a software implementation issue on > the chromeos-3.14 branch. With mainline kernel, you can use > devfreq and no platform files at all (that's how I tested these > dt bindings). So as far as I know, there's no need for a vendor > compatible string on rk3288. > >> That doesn't even take into account that there may even be differences >> on how things are synthesized that we don't know about. See all the >> variants of the dw_hdmi ip block (imx, rockchip, meson [more?]) . > > I'm not too familiar with that driver, just had a quick look and > it seems to be a different issue as there's a kernel config for > each platform to build separate driver modules. And it looks > like they are actually needed to cope with variants of the > hardware inside the display processor block, unlike with the Mali > GPU which in principle should always be the same. I've run this > Midgard driver without any platform files and using devfreq at > least on rk3288 Firefly, Exynos 5422 ODROID-XU3 and Juno and they > all have a vanilla Mali GPU hw block. It's just wired > differently in each SoC. Please, do not consider the "driver" in dt-bindings discussion, the way it's implemented is irrelevant here, but the way the IP is integrated is crucial. And trust me, HW designers and integrators are very very creative guys, and we *need* some platform code to handle integration corner cases not handled by the "IP" driver. In the case of "dw-hdmi", the "driver" acts like a "library" that can be used differently among the various platforms. I can talk about the "meson" Amlogic integration, in this particular case Amlogic used their owm PHY and wrapped all the stuff in a way we need to handle the PHY+HDMI+Wrapper in a single block and then connect it to the Video pipeline. For the midgard integration made by Amlogic, the vendor platform code uses tweaks to start the IP and initialize the clocks. And this code is part of the "amlogic,meson-gxm-mali" HW, not the "arm,midgard". > >> So we really want to have the special compatibles in place, to be prepared >> for the future per-soc oddities that always appear :-) . > > How about aiming for the ideal case where vendor-specific things > are not needed and add them if and when they really become > inevitable and worth the cost? Trust me, an amlogic compatible is needed ;-) Neil > > Thanks, > Guillaume > >> [0] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.14/drivers/gpu/arm/midgard/platform/rk/ >
Hi Neil, On 12/04/17 09:48, Neil Armstrong wrote: > Hi Guillaume, > > On 04/12/2017 10:25 AM, Guillaume Tucker wrote: >> Hi Heiko, >> >> On 11/04/17 21:52, Heiko Stübner wrote: >>> Hi Guillaume, >>> >>> Am Dienstag, 11. April 2017, 18:40:37 CEST schrieb Guillaume Tucker: >>>> On 03/04/17 09:12, Neil Armstrong wrote: >>>>> On 04/02/2017 09:59 AM, Guillaume Tucker wrote: >>>>>> +Optional: >>>>>> + >>>>>> +- clocks : Phandle to clock for the Mali Midgard device. >>>>>> +- clock-names : Shall be "clk_mali". >>>>>> +- mali-supply : Phandle to regulator for the Mali device. Refer to >>>>>> + Documentation/devicetree/bindings/regulator/regulator.txt for details. >>>>>> +- operating-points : Refer to >>>>>> Documentation/devicetree/bindings/power/opp.txt + for details. >>>>> >>>>> Please add : >>>>> * Must be one of the following: >>>>> "arm,mali-t820" >>>>> >>>>> * And, optionally, one of the vendor specific compatible: >>>>> "amlogic,meson-gxm-mali" >>>>> >>>>> with my Ack for the amlogic platform. >>>> >>>> It seems to me that as long as the GPU architecture hasn't been >>>> modified (I don't think I've ever encountered such a case) then >>>> it has to be a standard ARM Mali type regardless of the SoC >>>> vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the >>>> same as a T820 in a different SoC, please forgive me but I don't >>>> understand why a vendor compatible string is needed. My main >>>> concern is that it's going to be very hard to keep that list >>>> up-to-date with all existing Midgard SoC variants. If do we need >>>> to add vendor compatible strings to correctly describe the >>>> hardware then I'm happy to add the amlogic one in my patch v3; I >>>> would just like to understand why that's necessary. >>> >>> SoC vendors in most cases hook ip blocks into their socs in different >>> and often strange ways. After all it's not some discrete ic you solder >>> onto a board, but instead a part of the soc itself. >> >> Thanks for your explanation. I see, it's really about special >> things that are not supported by the standard Midgard kernel >> driver. >> >>> So in most cases you will have some hooks outside the actual gpu iospace >>> that can be used to tune different things about how the gpu interacts with >>> the system. Which is probably also the reason the midgard kernel driver >>> has this ugly "platform" subdirectory for compile-time platform selection. >> >> I see the "platform" directory approach as an old and deprecated >> way of supporting platforms, upstreaming the dt bindings goes in >> the direction of using solely the device tree to describe the GPU >> hardware (i.e. CONFIG_MALI_PLATFORM_DEVICETREE). If something >> quirky is needed in the platform, it should be possible to >> support it outside the GPU driver (platform devfreq etc...). > > If this was so simple... > > This is why the "vendor" compatible is optional. > > And on another side, the binding were written by ARM, are may not be > compatible with how the mainline Linux handles these uses-cases. > > ARM added some tweaks to handle some weird integration using DT properties, > but this should definitely go in platform specific code instead. OK, sorry I was approaching the issue from a completely different and somewhat more idealistic angle. My impression is that if the driver was in mainline then it would be maintained in such a way that vendor compatible strings would not be required, but this is all hypothetical. So in practice, I think I now better understand why vendor compatible strings may still be needed. And they're optional, so harmless to other platforms, so it's all fine with me :) >> Back to the original intent of enabling distros to make Mali GPU >> driver packages, when using the device tree you can have a single >> kernel driver package for all Midgard platforms. When using the >> third-party platform sources approach, you need to make an extra >> package for each one of them. > > Well, if the midgard driver was maintained in community-driven way, all vendor > could actually push their platform code, but it's not the case and somehow > never will. > >> >> So if there is value in supporting platforms that absolutely >> require something special due to their hardware GPU integration, >> then yes I see why vendor dt bindings might be useful. However >> it seems to me that this should really be an exception and >> avoided whenever possible. > > I understand you would avoid changing the (horrible) way the midgard > driver handles the DT... > > But ultimately, if we consider the eventual integration of the midgard > driver in mainline kernel (because why not ?), the driver would need > a complete re-write to conform the actual driver coding structure, > and so would also need to conform to the DT mainline rules. Yes, it's hard to have a discussion without a mainline driver to back things up. So I understand the pragmatic approach here. >>> On my rk3288 for example we have [0] in the chromeos tree, that handles >>> the oddities of the midgard on the rk3288 used in a lot of Chromebooks. >>> There are soc-specific oddities of frequencies, frequency-scaling and >>> whatnot. And there are also more gpu-specific setting in syscon areas >>> of the soc (pmu and grf) that can also influence the gpus performance >>> and might need tweaking at some point. >> >> For the rk3288, this is purely a software implementation issue on >> the chromeos-3.14 branch. With mainline kernel, you can use >> devfreq and no platform files at all (that's how I tested these >> dt bindings). So as far as I know, there's no need for a vendor >> compatible string on rk3288. >> >>> That doesn't even take into account that there may even be differences >>> on how things are synthesized that we don't know about. See all the >>> variants of the dw_hdmi ip block (imx, rockchip, meson [more?]) . >> >> I'm not too familiar with that driver, just had a quick look and >> it seems to be a different issue as there's a kernel config for >> each platform to build separate driver modules. And it looks >> like they are actually needed to cope with variants of the >> hardware inside the display processor block, unlike with the Mali >> GPU which in principle should always be the same. I've run this >> Midgard driver without any platform files and using devfreq at >> least on rk3288 Firefly, Exynos 5422 ODROID-XU3 and Juno and they >> all have a vanilla Mali GPU hw block. It's just wired >> differently in each SoC. > > Please, do not consider the "driver" in dt-bindings discussion, the > way it's implemented is irrelevant here, but the way the IP is > integrated is crucial. > And trust me, HW designers and integrators are very very creative > guys, and we *need* some platform code to handle integration corner > cases not handled by the "IP" driver. Sure, I know this happens... I can't help but think that if something quirky is done in the SoC around the GPU then it shouldn't need to be fixed in the GPU driver. But that's talking about the "driver" again, so not relevant. > In the case of "dw-hdmi", the "driver" acts like a "library" that > can be used differently among the various platforms. > > I can talk about the "meson" Amlogic integration, in this particular > case Amlogic used their owm PHY and wrapped all the stuff in a way > we need to handle the PHY+HDMI+Wrapper in a single block and then > connect it to the Video pipeline. > > For the midgard integration made by Amlogic, the vendor platform code > uses tweaks to start the IP and initialize the clocks. > And this code is part of the "amlogic,meson-gxm-mali" HW, not the > "arm,midgard". Can't this be done in the clock driver or some other early init stage of the SoC? But again, that code is not in mainline so it's a non-issue. >>> So we really want to have the special compatibles in place, to be prepared >>> for the future per-soc oddities that always appear :-) . >> >> How about aiming for the ideal case where vendor-specific things >> are not needed and add them if and when they really become >> inevitable and worth the cost? > > Trust me, an amlogic compatible is needed ;-) Fair enough, will add the optional vendor compatible string in my patch v3 :) Glad this was discussed though, thank you. Guillaume >>> [0] https://chromium.googlesource.com/chromiumos/third_party/kernel/+/chromeos-3.14/drivers/gpu/arm/midgard/platform/rk/
Hi Rob, On 04/04/17 03:00, Rob Herring wrote: > On Sun, Apr 02, 2017 at 08:59:44AM +0100, Guillaume Tucker wrote: >> The ARM Mali Midgard GPU family is present in a number of SoCs >> from many different vendors such as Samsung Exynos and Rockchip. >> >> Import the device tree bindings documentation from the r16p0 >> release of the Mali Midgard GPU kernel driver: >> >> https://developer.arm.com/-/media/Files/downloads/mali-drivers/kernel/mali-midgard-gpu/TX011-SW-99002-r16p0-00rel0.tgz >> >> The following optional bindings have been omitted in this initial >> version as they are only used in very specific cases: >> >> * snoop_enable_smc >> * snoop_disable_smc >> * jm_config >> * power_model >> * system-coherency >> * ipa-model >> >> The example has been simplified accordingly. >> >> The compatible string definition has been limited to >> "arm,mali-midgard" to avoid checkpatch.pl warnings and to match >> what the driver actually expects (as of r16p0 out-of-tree). >> >> CC: John Reitan <john.reitan@arm.com> >> Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com> >> --- >> .../devicetree/bindings/gpu/arm,mali-midgard.txt | 53 ++++++++++++++++++++++ >> 1 file changed, 53 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> >> diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> new file mode 100644 >> index 000000000000..da8fc6d21bbf >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt >> @@ -0,0 +1,53 @@ >> +# >> +# (C) COPYRIGHT 2013-2016 ARM Limited. >> +# Copyright (C) 2017 Collabora Ltd >> +# >> +# This program is free software and is provided to you under the terms of the >> +# GNU General Public License version 2 as published by the Free Software >> +# Foundation, and any use by you of this program is subject to the terms >> +# of such GNU licence. >> +# >> + >> + >> +ARM Mali Midgard GPU >> +==================== >> + >> +Required properties: >> + >> +- compatible : Should be "arm,mali-midgard". > > As Neil said... Sure; as discussed in my previous emails. >> +- reg : Physical base address of the device and length of the register area. >> +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. >> +- interrupt-names : Contains the names of IRQ resources in the order they were >> + provided in the interrupts property. Must contain: "JOB, "MMU", "GPU". >> + >> +Optional: >> + >> +- clocks : Phandle to clock for the Mali Midgard device. >> +- clock-names : Shall be "clk_mali". > > "clk_" is redundant. Actually, if there is only 1 clock, then just drop > names. But there's not at least a core and bus clock? Only one clock needs to be provided with the Midgard GPU architecture. It shares the same bus and system memory as the CPU. So I'll remove clock-names in patch v3. >> +- mali-supply : Phandle to regulator for the Mali device. Refer to >> + Documentation/devicetree/bindings/regulator/regulator.txt for details. >> +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt >> + for details. > > Is this going to be sufficient vs. operating-points-v2? Or should it be > a power domain with OPPs? In principle, switching to operating-points-v2 should be very straightforward. I have smoke-tested the driver with an operating-points-v2 table and a phandle to it inside the gpu node in place of operating-points and it seems to be working fine. At least it parsed the OPPs and got initialised correctly. My understanding is that operating-points (v1) are not deprecated so we could keep the bindings as-is, but please let me know otherwise and I can try to address that in my next patch version. In the documentation, it should only be the case of replacing operating-points with operating-points-v2. >> + >> +Example for a Mali-T602: >> + >> +gpu@0xfc010000 { > > Drop the '0x'. OK, I'm also updating the example with lower-case IRQ names, no clock-names etc... Thanks, Guillaume
On 18/04/17 10:15, Guillaume Tucker wrote: > Hi Rob, > > On 04/04/17 03:00, Rob Herring wrote: >> On Sun, Apr 02, 2017 at 08:59:44AM +0100, Guillaume Tucker wrote: >>> +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt >>> + for details. >> >> Is this going to be sufficient vs. operating-points-v2? Or should it be >> a power domain with OPPs? > > In principle, switching to operating-points-v2 should be very > straightforward. I have smoke-tested the driver with an > operating-points-v2 table and a phandle to it inside the gpu node > in place of operating-points and it seems to be working fine. At > least it parsed the OPPs and got initialised correctly. > > My understanding is that operating-points (v1) are not deprecated > so we could keep the bindings as-is, but please let me know > otherwise and I can try to address that in my next patch version. > In the documentation, it should only be the case of replacing > operating-points with operating-points-v2. While the opp bindings documentation doesn't mention anything about operating-points being deprecated, the code and comments in of.c are pretty clear about this: /* * OPPs have two version of bindings now. The older one is deprecated, * try for the new binding first. */ So I shall use operating-points-v2 in my patch v4. Thanks, Guillaume
On Wed, Apr 12, 2017 at 4:36 AM, Guillaume Tucker <guillaume.tucker@collabora.com> wrote: > Hi Neil, > > > On 12/04/17 09:48, Neil Armstrong wrote: >> >> Hi Guillaume, >> >> On 04/12/2017 10:25 AM, Guillaume Tucker wrote: >>> >>> Hi Heiko, >>> >>> On 11/04/17 21:52, Heiko Stübner wrote: >>>> >>>> Hi Guillaume, >>>> >>>> Am Dienstag, 11. April 2017, 18:40:37 CEST schrieb Guillaume Tucker: >>>>> >>>>> On 03/04/17 09:12, Neil Armstrong wrote: >>>>>> >>>>>> On 04/02/2017 09:59 AM, Guillaume Tucker wrote: >>>>>>> >>>>>>> +Optional: >>>>>>> + >>>>>>> +- clocks : Phandle to clock for the Mali Midgard device. >>>>>>> +- clock-names : Shall be "clk_mali". >>>>>>> +- mali-supply : Phandle to regulator for the Mali device. Refer to >>>>>>> + Documentation/devicetree/bindings/regulator/regulator.txt for >>>>>>> details. >>>>>>> +- operating-points : Refer to >>>>>>> Documentation/devicetree/bindings/power/opp.txt + for details. >>>>>> >>>>>> >>>>>> Please add : >>>>>> * Must be one of the following: >>>>>> "arm,mali-t820" >>>>>> >>>>>> * And, optionally, one of the vendor specific compatible: >>>>>> "amlogic,meson-gxm-mali" >>>>>> >>>>>> with my Ack for the amlogic platform. >>>>> >>>>> >>>>> It seems to me that as long as the GPU architecture hasn't been >>>>> modified (I don't think I've ever encountered such a case) then >>>>> it has to be a standard ARM Mali type regardless of the SoC >>>>> vendor. So unless a Mali-T820 in the Amlogic S912 SoC is not the >>>>> same as a T820 in a different SoC, please forgive me but I don't >>>>> understand why a vendor compatible string is needed. My main >>>>> concern is that it's going to be very hard to keep that list >>>>> up-to-date with all existing Midgard SoC variants. If do we need >>>>> to add vendor compatible strings to correctly describe the >>>>> hardware then I'm happy to add the amlogic one in my patch v3; I >>>>> would just like to understand why that's necessary. >>>> >>>> >>>> SoC vendors in most cases hook ip blocks into their socs in different >>>> and often strange ways. After all it's not some discrete ic you solder >>>> onto a board, but instead a part of the soc itself. >>> >>> >>> Thanks for your explanation. I see, it's really about special >>> things that are not supported by the standard Midgard kernel >>> driver. >>> >>>> So in most cases you will have some hooks outside the actual gpu iospace >>>> that can be used to tune different things about how the gpu interacts >>>> with >>>> the system. Which is probably also the reason the midgard kernel driver >>>> has this ugly "platform" subdirectory for compile-time platform >>>> selection. >>> >>> >>> I see the "platform" directory approach as an old and deprecated >>> way of supporting platforms, upstreaming the dt bindings goes in >>> the direction of using solely the device tree to describe the GPU >>> hardware (i.e. CONFIG_MALI_PLATFORM_DEVICETREE). If something >>> quirky is needed in the platform, it should be possible to >>> support it outside the GPU driver (platform devfreq etc...). >> >> >> If this was so simple... >> >> This is why the "vendor" compatible is optional. >> >> And on another side, the binding were written by ARM, are may not be >> compatible with how the mainline Linux handles these uses-cases. >> >> ARM added some tweaks to handle some weird integration using DT >> properties, >> but this should definitely go in platform specific code instead. > > > OK, sorry I was approaching the issue from a completely different > and somewhat more idealistic angle. My impression is that if the > driver was in mainline then it would be maintained in such a way > that vendor compatible strings would not be required, but this is > all hypothetical. > > So in practice, I think I now better understand why vendor > compatible strings may still be needed. And they're optional, so > harmless to other platforms, so it's all fine with me :) SoC specific compatibles are required. They are only optional for a driver to use. Rob
diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt new file mode 100644 index 000000000000..da8fc6d21bbf --- /dev/null +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt @@ -0,0 +1,53 @@ +# +# (C) COPYRIGHT 2013-2016 ARM Limited. +# Copyright (C) 2017 Collabora Ltd +# +# This program is free software and is provided to you under the terms of the +# GNU General Public License version 2 as published by the Free Software +# Foundation, and any use by you of this program is subject to the terms +# of such GNU licence. +# + + +ARM Mali Midgard GPU +==================== + +Required properties: + +- compatible : Should be "arm,mali-midgard". +- reg : Physical base address of the device and length of the register area. +- interrupts : Contains the three IRQ lines required by Mali Midgard devices. +- interrupt-names : Contains the names of IRQ resources in the order they were + provided in the interrupts property. Must contain: "JOB, "MMU", "GPU". + +Optional: + +- clocks : Phandle to clock for the Mali Midgard device. +- clock-names : Shall be "clk_mali". +- mali-supply : Phandle to regulator for the Mali device. Refer to + Documentation/devicetree/bindings/regulator/regulator.txt for details. +- operating-points : Refer to Documentation/devicetree/bindings/power/opp.txt + for details. + +Example for a Mali-T602: + +gpu@0xfc010000 { + compatible = "arm,mali-midgard"; + reg = <0xfc010000 0x4000>; + interrupts = <0 36 4>, <0 37 4>, <0 38 4>; + interrupt-names = "JOB", "MMU", "GPU"; + + clocks = <&pclk_mali>; + clock-names = "clk_mali"; + mali-supply = <&vdd_mali>; + operating-points = < + /* KHz uV */ + 533000 1250000, + 450000 1150000, + 400000 1125000, + 350000 1075000, + 266000 1025000, + 160000 925000, + 100000 912500, + >; +};
The ARM Mali Midgard GPU family is present in a number of SoCs from many different vendors such as Samsung Exynos and Rockchip. Import the device tree bindings documentation from the r16p0 release of the Mali Midgard GPU kernel driver: https://developer.arm.com/-/media/Files/downloads/mali-drivers/kernel/mali-midgard-gpu/TX011-SW-99002-r16p0-00rel0.tgz The following optional bindings have been omitted in this initial version as they are only used in very specific cases: * snoop_enable_smc * snoop_disable_smc * jm_config * power_model * system-coherency * ipa-model The example has been simplified accordingly. The compatible string definition has been limited to "arm,mali-midgard" to avoid checkpatch.pl warnings and to match what the driver actually expects (as of r16p0 out-of-tree). CC: John Reitan <john.reitan@arm.com> Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com> --- .../devicetree/bindings/gpu/arm,mali-midgard.txt | 53 ++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt