linux-kernel - Re: [PATCH] mmc: Fix force card detect in sdhci

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Message-ID: <9a311ce3-0d29-af39-5533-c1cad6de1300@microchip.com>
Date:   Sat, 23 Sep 2023 14:44:54 +0200
From:   Aubin Constans <aubin.constans@...rochip.com>
To:     Mathieu Moneyron <mathieu.moneyron@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        "Alexandre Belloni" <alexandre.belloni@...tlin.com>,
        Eugen Hristev <eugen.hristev@...labora.com>
CC:     Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Nicolas Ferre <nicolas.ferre@...rochip.com>,
        <linux-mmc@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: Fix force card detect in sdhci

On 04/09/2023 09:38, Adrian Hunter wrote:
> + Eugen Hristev  > > On 30/08/23 12:23, mathieu wrote: >> On the ATMEL at91 when using 
the non-removable flag in device tree >> and not using the card-detect 
pin inside the device-tree pinctrl, >> the card detect pin is physically 
still used which can cause >> unknown behaviour when this pin is used 
for other purposes.
Hi Mathieu,

On which SoC(s) exactly, has this behaviour been observed?

Also, has this issue been discussed in any separate support request, in such
case we could retrieve some background from it?

By "unknown behaviour", do you mean "the card insertion status would
follow whatever electrical level is seen on the card-detect pin"?

>>  >> From my interpretation this seems to be caused by a hardware design 
 >> flaw and the real hardware is not working as intended by the >> 
documentation. >>
>>
>> Signed-off-by: Mathieu Moneyron <mathieu.moneyron@...il.com>
>>
>> ---
>>  drivers/mmc/host/sdhci-of-at91.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/mmc/host/sdhci-of-at91.c 
>> b/drivers/mmc/host/sdhci-of-at91.c
>> index 69fef88e7..4fd6bfbf6 100644
>> --- a/drivers/mmc/host/sdhci-of-at91.c
>> +++ b/drivers/mmc/host/sdhci-of-at91.c
>> @@ -51,10 +51,15 @@ struct sdhci_at91_priv {
>>  static void sdhci_at91_set_force_card_detect(struct sdhci_host *host)
>>  {
>>      u8 mc1r;
>> +    u8 ctrl;
>>
>>      mc1r = readb(host->ioaddr + SDMMC_MC1R);
>>      mc1r |= SDMMC_MC1R_FCD;
>>      writeb(mc1r, host->ioaddr + SDMMC_MC1R);
>> +
>> +    ctrl = readb(host->ioaddr + SDHCI_HOST_CONTROL);
>> +    ctrl |= SDHCI_CTRL_CDTEST_INS | SDHCI_CTRL_CDTEST_EN;
>> +    writeb(ctrl, host->ioaddr + SDHCI_HOST_CONTROL);
>>  }
>>
>>  static void sdhci_at91_set_clock(struct sdhci_host *host, unsigned 
>> int clock)

Kind regards,
Aubin