linux-kernel - Re: [RFC PATCH 2/2] mmc: sdhci: Quirk for AMD SDHC Device 0x7906

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Message-ID: <CAPDyKFq8T0kdJsPfk6ue2OaQUO9L_oOwnxDw=-FVboZRyKJPdA@mail.gmail.com>
Date:   Tue, 28 May 2019 09:41:07 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Raul E Rangel <rrangel@...omium.org>
Cc:     "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        Daniel Kurtz <djkurtz@...omium.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: Re: [RFC PATCH 2/2] mmc: sdhci: Quirk for AMD SDHC Device 0x7906

On Wed, 1 May 2019 at 19:55, Raul E Rangel <rrangel@...omium.org> wrote:
>
> AMD SDHC 0x7906 requires a hard reset to clear all internal state.
> Otherwise it can get into a bad state where the DATA lines are always
> read as zeros.
>
> This change requires firmware that can transition the device into
> D3Cold for it to work correctly. If the firmware does not support
> transitioning to D3Cold then the power state transitions are a no-op.
>
> Signed-off-by: Raul E Rangel <rrangel@...omium.org>

Does this also solve the problem you tried to fix in patch1, without patch1?

Should this have a stable tag?

Kind regards
Uffe

> ---
>
>  drivers/mmc/host/sdhci-pci-core.c | 51 ++++++++++++++++++++++++++++++-
>  1 file changed, 50 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/sdhci-pci-core.c b/drivers/mmc/host/sdhci-pci-core.c
> index 99b0fec2836b..532fbcbd373b 100644
> --- a/drivers/mmc/host/sdhci-pci-core.c
> +++ b/drivers/mmc/host/sdhci-pci-core.c
> @@ -25,6 +25,7 @@
>  #include <linux/mmc/mmc.h>
>  #include <linux/scatterlist.h>
>  #include <linux/io.h>
> +#include <linux/iopoll.h>
>  #include <linux/gpio.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/mmc/slot-gpio.h>
> @@ -1498,11 +1499,59 @@ static int amd_probe(struct sdhci_pci_chip *chip)
>         return 0;
>  }
>
> +static u32 sdhci_read_present_state(struct sdhci_host *host)
> +{
> +       return sdhci_readl(host, SDHCI_PRESENT_STATE);
> +}
> +
> +void amd_sdhci_reset(struct sdhci_host *host, u8 mask)
> +{
> +       struct sdhci_pci_slot *slot = sdhci_priv(host);
> +       struct pci_dev *pdev = slot->chip->pdev;
> +       u32 present_state;
> +
> +       /*
> +        * SDHC 0x7906 requires a hard reset to clear all internal state.
> +        * Otherwise it can get into a bad state where the DATA lines are always
> +        * read as zeros.
> +        */
> +       if (pdev->device == 0x7906 && (mask & SDHCI_RESET_ALL)) {
> +               pci_clear_master(pdev);
> +
> +               pci_save_state(pdev);
> +
> +               pci_set_power_state(pdev, PCI_D3cold);
> +               pr_debug("%s: power_state=%u\n", mmc_hostname(host->mmc),
> +                       pdev->current_state);
> +               pci_set_power_state(pdev, PCI_D0);
> +
> +               pci_restore_state(pdev);
> +
> +               /*
> +                * SDHCI_RESET_ALL says the card detect logic should not be
> +                * reset, but since we need to reset the entire controller
> +                * we should wait until the card detect logic has stabilized.
> +                *
> +                * This normally takes about 40ms.
> +                */
> +               readx_poll_timeout(
> +                       sdhci_read_present_state,
> +                       host,
> +                       present_state,
> +                       present_state & SDHCI_CD_STABLE,
> +                       10000,
> +                       100000
> +               );
> +       }
> +
> +       return sdhci_reset(host, mask);
> +}
> +
>  static const struct sdhci_ops amd_sdhci_pci_ops = {
>         .set_clock                      = sdhci_set_clock,
>         .enable_dma                     = sdhci_pci_enable_dma,
>         .set_bus_width                  = sdhci_set_bus_width,
> -       .reset                          = sdhci_reset,
> +       .reset                          = amd_sdhci_reset,
>         .set_uhs_signaling              = sdhci_set_uhs_signaling,
>  };
>
> --
> 2.21.0.593.g511ec345e18-goog
>