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

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On 23/09/2023 16:23, Mathieu Moneyron wrote:
Hi Aubin,

Thanks for your feedback.
I'll try my best to give clear explanations.

On Sat, Sep 23, 2023 at 2:44 PM Aubin Constans
<aubin.constans@xxxxxxxxxxxxx> wrote:

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?

This has been observed on SAMA5D27.

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"?

For instance our board design has the PA13 (card detect) pin wired to drive a
3v3 power supply.
The fixed regulator driver configure this pin as output (described in the device
But what I observed is that the sdmmc driver still want to use PA13 as the card
detect signal which is then configured as an input. This cause the 3v3 power to

In the device tree, has PIN_PA13__SDMMC0_CD been removed from the pinctrl for sdmmc0?

In case the above behaviour was due to hardware, it would likely point out a flaw in the Parallel Input/Output Controller (PIO) rather than in the SDMMC Controller.

Would you read back the relevant PIO_CFGRx register, with only "PA13" set in PIO_MSKRx, and provide me with the value read? Assuming PA13 is Non-Secure; if PA13 is configured as Secure, S_PIO_CFGRx and S_PIO_MSKRx should be accessed instead.

By "unknown behavior" I mean the configuration of this pin as card detect sets
unwanted electrical levels to what's connected to this 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@xxxxxxxxx>

  drivers/mmc/host/sdhci-of-at91.c | 5 +++++
  1 file changed, 5 insertions(+)

diff --git a/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);
+    writeb(ctrl, host->ioaddr + SDHCI_HOST_CONTROL);

  static void sdhci_at91_set_clock(struct sdhci_host *host, unsigned
int clock)

Kind regards,

Kind regards,

Thank you,

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