| Message ID | 20180712080725.14250-1-stefan@agner.ch (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Stefan Agner [mailto:stefan@agner.ch] > Sent: Thursday, July 12, 2018 4:07 PM > To: adrian.hunter@intel.com; ulf.hansson@linaro.org > Cc: Fabio Estevam <fabio.estevam@nxp.com>; Bough Chen > <haibo.chen@nxp.com>; A.s. Dong <aisheng.dong@nxp.com>; linux- > mmc@vger.kernel.org; linux-kernel@vger.kernel.org; Stefan Agner > <stefan@agner.ch> > Subject: [PATCH v2 1/2] mmc: sdhci-esdhc-imx: disable clocks before > changing frequency > > In the uSDHC case (e.g. i.MX 6) clocks only get disabled if frequency is set to 0. > However, it could be that the stack asks for a frequency change while clocks > are on. In that case the function clears the divider registers (by clearing > ESDHC_CLOCK_MASK) while the clock is enabled! This causes a short period > of time where the clock is undivided (on a i.MX 6DL a clock of 196MHz has > been measured). > > For older IP variants the driver disables clock by clearing some bits in > ESDHC_SYSTEM_CONTROL. > > Make sure to disable card clock before changing frequency for uSDHC IP > variants too. Looks ok to me. Acked-by: Dong Aisheng <aisheng.dong@nxp.com> Regards Dong Aisheng > > Signed-off-by: Stefan Agner <stefan@agner.ch> > --- > drivers/mmc/host/sdhci-esdhc-imx.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci- > esdhc-imx.c > index 85fd5a8b0b6d..acacd8481473 100644 > --- a/drivers/mmc/host/sdhci-esdhc-imx.c > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c > @@ -708,14 +708,14 @@ static inline void esdhc_pltfm_set_clock(struct > sdhci_host *host, > int div = 1; > u32 temp, val; > > + if (esdhc_is_usdhc(imx_data)) { > + val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); > + writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, > + host->ioaddr + ESDHC_VENDOR_SPEC); > + } > + > if (clock == 0) { > host->mmc->actual_clock = 0; > - > - if (esdhc_is_usdhc(imx_data)) { > - val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); > - writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, > - host->ioaddr + > ESDHC_VENDOR_SPEC); > - } > return; > } > > -- > 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/07/18 11:07, Stefan Agner wrote: > In the uSDHC case (e.g. i.MX 6) clocks only get disabled if frequency > is set to 0. However, it could be that the stack asks for a frequency > change while clocks are on. In that case the function clears the > divider registers (by clearing ESDHC_CLOCK_MASK) while the clock is > enabled! This causes a short period of time where the clock is > undivided (on a i.MX 6DL a clock of 196MHz has been measured). > > For older IP variants the driver disables clock by clearing some bits > in ESDHC_SYSTEM_CONTROL. > > Make sure to disable card clock before changing frequency for uSDHC > IP variants too. > > Signed-off-by: Stefan Agner <stefan@agner.ch> Acked-by: Adrian Hunter <adrian.hunter@intel.com> > --- > drivers/mmc/host/sdhci-esdhc-imx.c | 12 ++++++------ > 1 file changed, 6 insertions(+), 6 deletions(-) > > diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c > index 85fd5a8b0b6d..acacd8481473 100644 > --- a/drivers/mmc/host/sdhci-esdhc-imx.c > +++ b/drivers/mmc/host/sdhci-esdhc-imx.c > @@ -708,14 +708,14 @@ static inline void esdhc_pltfm_set_clock(struct sdhci_host *host, > int div = 1; > u32 temp, val; > > + if (esdhc_is_usdhc(imx_data)) { > + val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); > + writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, > + host->ioaddr + ESDHC_VENDOR_SPEC); > + } > + > if (clock == 0) { > host->mmc->actual_clock = 0; > - > - if (esdhc_is_usdhc(imx_data)) { > - val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); > - writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, > - host->ioaddr + ESDHC_VENDOR_SPEC); > - } > return; > } > > -- To unsubscribe from this list: send the line "unsubscribe linux-mmc" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c index 85fd5a8b0b6d..acacd8481473 100644 --- a/drivers/mmc/host/sdhci-esdhc-imx.c +++ b/drivers/mmc/host/sdhci-esdhc-imx.c @@ -708,14 +708,14 @@ static inline void esdhc_pltfm_set_clock(struct sdhci_host *host, int div = 1; u32 temp, val; + if (esdhc_is_usdhc(imx_data)) { + val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); + writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, + host->ioaddr + ESDHC_VENDOR_SPEC); + } + if (clock == 0) { host->mmc->actual_clock = 0; - - if (esdhc_is_usdhc(imx_data)) { - val = readl(host->ioaddr + ESDHC_VENDOR_SPEC); - writel(val & ~ESDHC_VENDOR_SPEC_FRC_SDCLK_ON, - host->ioaddr + ESDHC_VENDOR_SPEC); - } return; }
In the uSDHC case (e.g. i.MX 6) clocks only get disabled if frequency is set to 0. However, it could be that the stack asks for a frequency change while clocks are on. In that case the function clears the divider registers (by clearing ESDHC_CLOCK_MASK) while the clock is enabled! This causes a short period of time where the clock is undivided (on a i.MX 6DL a clock of 196MHz has been measured). For older IP variants the driver disables clock by clearing some bits in ESDHC_SYSTEM_CONTROL. Make sure to disable card clock before changing frequency for uSDHC IP variants too. Signed-off-by: Stefan Agner <stefan@agner.ch> --- drivers/mmc/host/sdhci-esdhc-imx.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)