Messages in this thread | | | Date | Mon, 14 Mar 2022 17:51:53 +0100 | Subject | Re: [PATCH v2] mmc: mmci: manage MMC_PM_KEEP_POWER per variant config | From | Yann Gautier <> |
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On 3/14/22 17:18, Ulf Hansson wrote: > On Mon, 14 Mar 2022 at 15:34, Yann Gautier <yann.gautier@foss.st.com> wrote: >> >> On 3/14/22 14:03, Ulf Hansson wrote: >>> On Mon, 14 Mar 2022 at 13:56, Yann Gautier <yann.gautier@foss.st.com> wrote: >>>> >>>> Add a disable_keep_power field in variant_data struct. The >>>> MMC_PM_KEEP_POWER flag will be enabled if disable_keep_power is not set. >>>> It is only set to true for stm32_sdmmc variants. >>>> >>>> The issue was seen on STM32MP157C-DK2 board, which embeds a wifi chip. >>>> It doesn't correctly support low power on this board. The Wifi chip >>>> awaits an always-on regulator, but it was connected to v3v3 which is off >>>> in low-power sequence. MMC_PM_KEEP_POWER should then be disabled. >>> >>> Just to make sure I get this correct. >>> >>> Why can't the regulator stay on during system suspend? The point is, >>> we don't need an always on regulator to cope with this. >>> >>> Kind regards >>> Uffe >> >> Hi Ulf, >> >> This v3v3 regulator powers most of the devices on this board. So we need >> to switch it off to gain power in suspend mode. > > I see. Thanks for sharing that information. > > The MMC_PM_KEEP_POWER flag is there to describe what is supported by > the platform/host. It doesn't mean that the card *must* stay powered > on during system suspend. Instead that depends on whether system > wakeup for the SDIO/WiFi is supported too - and if that is enabled by > userspace. If not, the regulator will be turned off for the SDIO card > during system suspend. > > Assuming the regulator is implemented as a proper regulator and can > remain on during system suspend, the right thing would be to keep the > MMC_PM_KEEP_POWER flag around. > > Kind regards > Uffe >
OK, but in the wifi driver we use on this platform (brcmfmac), the suspend/resume functions (brcmf_ops_sdio_suspend/brcmf_ops_sdio_resume) use the flag to check regu was off, and then call probe function during resume, to re-init Wifi chip and reload its firmware.
Best regards, Yann
>> >> >> Yann >> >>> >>>> >>>> The flag can still be enabled through DT property: >>>> keep-power-in-suspend. >>>> >>>> Signed-off-by: Yann Gautier <yann.gautier@foss.st.com> >>>> --- >>>> Update in v2: >>>> Reword commit message to better explain the issue. >>>> >>>> Resend the patch alone. It was previoulsy in a series [1] for which the >>>> other patches will be reworked. >>>> >>>> [1] https://lore.kernel.org/lkml/20220304135134.47827-1-yann.gautier@foss.st.com/ >>>> >>>> drivers/mmc/host/mmci.c | 5 ++++- >>>> drivers/mmc/host/mmci.h | 1 + >>>> 2 files changed, 5 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c >>>> index 45b8608c935c..0e2f2f5d6a52 100644 >>>> --- a/drivers/mmc/host/mmci.c >>>> +++ b/drivers/mmc/host/mmci.c >>>> @@ -274,6 +274,7 @@ static struct variant_data variant_stm32_sdmmc = { >>>> .busy_detect = true, >>>> .busy_detect_flag = MCI_STM32_BUSYD0, >>>> .busy_detect_mask = MCI_STM32_BUSYD0ENDMASK, >>>> + .disable_keep_power = true, >>>> .init = sdmmc_variant_init, >>>> }; >>>> >>>> @@ -301,6 +302,7 @@ static struct variant_data variant_stm32_sdmmcv2 = { >>>> .busy_detect = true, >>>> .busy_detect_flag = MCI_STM32_BUSYD0, >>>> .busy_detect_mask = MCI_STM32_BUSYD0ENDMASK, >>>> + .disable_keep_power = true, >>>> .init = sdmmc_variant_init, >>>> }; >>>> >>>> @@ -2172,7 +2174,8 @@ static int mmci_probe(struct amba_device *dev, >>>> host->stop_abort.flags = MMC_RSP_R1B | MMC_CMD_AC; >>>> >>>> /* We support these PM capabilities. */ >>>> - mmc->pm_caps |= MMC_PM_KEEP_POWER; >>>> + if (!variant->disable_keep_power) >>>> + mmc->pm_caps |= MMC_PM_KEEP_POWER; >>>> >>>> /* >>>> * We can do SGIO >>>> diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h >>>> index e1a9b96a3396..2cad1ef9766a 100644 >>>> --- a/drivers/mmc/host/mmci.h >>>> +++ b/drivers/mmc/host/mmci.h >>>> @@ -361,6 +361,7 @@ struct variant_data { >>>> u32 opendrain; >>>> u8 dma_lli:1; >>>> u32 stm32_idmabsize_mask; >>>> + u8 disable_keep_power:1; >>>> void (*init)(struct mmci_host *host); >>>> }; >>>> >>>> -- >>>> 2.25.1 >>>> >>
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