[Linux-stm32] [PATCH 2/4] mmc: mmci: Add support for probing bus voltage level translator

[Yann GAUTIER]

On 1/16/21 7:04 PM, Marek Vasut wrote:
> Add support for testing whether bus voltage level translator is present
> and operational. This is useful on systems where the bus voltage level
> translator is optional, as the translator can be auto-detected by the
> driver and the feedback clock functionality can be disabled if it is
> not present.
> 
> This requires additional pinmux state, "init", where the CMD, CK, CKIN
> lines are not configured, so they can be claimed as GPIOs early on in
> probe(). The translator test sets CMD high to avoid interfering with a
> card, and then verifies whether signal set on CK is detected on CKIN.
> If the signal is detected, translator is present, otherwise the CKIN
> feedback clock are disabled.
> 
> Signed-off-by: Marek Vasut<marex at denx.de>
> Cc: Alexandre Torgue<alexandre.torgue at st.com>
> Cc: Linus Walleij<linus.walleij at linaro.org>
> Cc: Ludovic Barre<ludovic.barre at st.com>
> Cc: Ulf Hansson<ulf.hansson at linaro.org>
> Cc:linux-stm32 at st-md-mailman.stormreply.com

Hi Marek,

I've tested it on STM32MP157C-EV1 (which uses st,use-ckin) and 
STM32MP157C-DK2 (which doesn't). The mmc_test sessions are OK on both 
boards.
Feel free to add my:
Tested-by: Yann Gautier <yann.gautier at foss.st.com>


Regards,
Yann