linux-kernel - Re: [PATCH] sdhci: Fix SD card detection issue

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Date: Mon, 15 Apr 2024 16:11:56 +0800
From: richard clark <richard.xnu.clark@...il.com>
To: Adrian Hunter <adrian.hunter@...el.com>
Cc: ulf.hansson@...aro.org, linux-mmc@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] sdhci: Fix SD card detection issue

On Mon, Apr 15, 2024 at 3:18 PM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> On 15/04/24 10:06, Richard Clark wrote:
> > The mmc_gpio_get_cd(...) will return 0 called from sdhci_get_cd(...), which means
> > the card is not present. Actually, the card detection pin is active low by default
> > according to the SDHCI psec, thus the card detection result is not correct, more
>
> SDHCI spec covers the SDHCI lines.  GPIO is separate.
>
> > specificly below if condition is true in mmc_rescan(...):
> >       ...
> >       if (mmc_card_is_removable(host) && host->ops->get_cd &&
> >               host->ops->get_cd(host) == 0) {
> >               ...
> >               goto out;
> >       }
> > The SD card device will have no chance to be created.
> >
> > This commit fixes this detection issue via the MMC_CAP2_CD_ACTIVE_HIGH cap2 flag,
> > parsed from the 'cd-inverted' property of DT.
>
> What hardware / driver is it?
sdhci-tegra on Orin.
> >
> > Signed-off-by: Richard Clark <richard.xnu.clark@...il.com>
> > ---
> >  drivers/mmc/host/sdhci.c | 3 +++
> >  1 file changed, 3 insertions(+)
> >
> > diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> > index c79f73459915..79f33a161ca8 100644
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -2483,6 +2483,9 @@ static int sdhci_get_cd(struct mmc_host *mmc)
> >        * Try slot gpio detect, if defined it take precedence
> >        * over build in controller functionality
> >        */
> > +     if (!(mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH))
> > +             gpio_cd = !gpio_cd;
>
> MMC_CAP2_CD_ACTIVE_HIGH is already handled in
> mmc_gpiod_request_cd(), and this turns an error (gpio_cd < 0)
> into 0, which is not right.

But in case of 'cd-inverted' is not specified, the gpio CD pin return
0 which will be explained as card is not present.
>
> > +
> >       if (gpio_cd >= 0)
> >               return !!gpio_cd;
> >
>