Re: [PATCH] mmc: mmci: stm32: handle mmc power up

[Marek Vasut <marex@nabladev.com>]

On 11/10/26 2:32 PM, Ulf Hansson wrote:
> On Fri, Oct 30, 2026 at 10:54 PM Marek Vasut <marex@nabladev.com> wrote:
>>
>> From: Christophe Kerello <christophe.kerello@foss.st.com>
>>
>> Manage MMC POWER UP state like MMC POWER OFF state. In case of low
>> power use cases, it will avoid random initialization timeout. This
>> fixes a failure to switch DDR52 eMMC to 8 bit mode due to -EILSEQ
>> returned from mmc_get_ext_csd() in mmc_compare_ext_csds() called
>> from mmc_select_bus_width() after Standby1 suspend/resume cycle.
>>
>> Fixes: 46b723dd867d ("mmc: mmci: add stm32 sdmmc variant")
>> Signed-off-by: Christophe Kerello <christophe.kerello@foss.st.com>
>> Signed-off-by: Marek Vasut <marex@nabladev.com>
>> ---
>> Cc: Alexandre Torgue <alexandre.torgue@foss.st.com>
>> Cc: Christophe Kerello <christophe.kerello@foss.st.com>
>> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com>
>> Cc: Ulf Hansson <ulfh@kernel.org>
>> Cc: kernel@dh-electronics.com
>> Cc: linux-arm-kernel@lists.infradead.org
>> Cc: linux-kernel@vger.kernel.org
>> Cc: linux-mmc@vger.kernel.org
>> Cc: linux-stm32@st-md-mailman.stormreply.com
>> ---
>> Marek: Update commit message
>> ---
>>   drivers/mmc/host/mmci_stm32_sdmmc.c | 3 ++-
>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
>> index 9dc51859c2e51..659a5040729e9 100644
>> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
>> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
>> @@ -368,7 +368,8 @@ static void mmci_sdmmc_set_pwrreg(struct mmci_host *host, unsigned int pwr)
>>          if (dlyb && dlyb->ops->set_input_ck)
>>                  dlyb->ops->set_input_ck(dlyb);
>>
>> -       if (ios.power_mode == MMC_POWER_OFF) {
>> +       if (ios.power_mode == MMC_POWER_OFF ||
>> +           ios.power_mode == MMC_POWER_UP) {
>>                  /* Only a reset could power-off sdmmc */
>>                  reset_control_assert(host->rst);
>>                  udelay(2);
> 
> What exactly will this reset?
The controller.