Re: [PATCH v2] mmc: meson-gx: fix SDIO interrupt handling

[Ulf Hansson]

On Tue, 22 Nov 2022 at 14:23, Peter Suti <peter.suti@xxxxxxxxxxxxxxxxxxx> wrote:
>
> With the interrupt support introduced in commit 066ecde sometimes the
> Marvell-8987 wifi chip entered a deadlock using the marvell-sd-uapsta-8987
> vendor driver. The cause seems to be that sometimes the interrupt handler
> handles 2 IRQs and one of them disables the interrupts which are not reenabled
> when all interrupts are finished. To work around this, disable all interrupts
> when we are in the IRQ context and reenable them when the current IRQ is handled.
>
> Fixes: 066ecde ("mmc: meson-gx: add SDIO interrupt support")
>
> Signed-off-by: Peter Suti <peter.suti@xxxxxxxxxxxxxxxxxxx>
> ---
> Changes in v2:
>         - use spin_lock instead of spin_lock_irqsave
>         - only reenable interrupts if they were enabled already
>
>  drivers/mmc/host/meson-gx-mmc.c | 30 +++++++++++++++++++++++-------
>  1 file changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 6e5ea0213b47..0c95f8640b34 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -934,6 +934,13 @@ static void meson_mmc_read_resp(struct mmc_host *mmc, struct mmc_command *cmd)
>         }
>  }
>
> +static bool __meson_mmc_sdio_irq_is_enabled(struct mmc_host *mmc)

Looks like it's better to pass a struct meson_host *host, rather than
a struct mmc_host *mmc.

> +{
> +       struct meson_host *host = mmc_priv(mmc);
> +
> +       return readl(host->regs + SD_EMMC_IRQ_EN) & IRQ_SDIO;
> +}
> +
>  static void __meson_mmc_enable_sdio_irq(struct mmc_host *mmc, int enable)
>  {
>         struct meson_host *host = mmc_priv(mmc);
> @@ -950,6 +957,11 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>         struct mmc_command *cmd;
>         u32 status, raw_status;
>         irqreturn_t ret = IRQ_NONE;
> +       bool irq_enabled;

Nitpick: (since I have a few comments anyway). May I suggest rename
this to sdio_irq_enabled instead?

> +
> +       spin_lock(&host->lock);
> +       irq_enabled = __meson_mmc_sdio_irq_is_enabled(host->mmc);
> +       __meson_mmc_enable_sdio_irq(host->mmc, 0);
>
>         raw_status = readl(host->regs + SD_EMMC_STATUS);
>         status = raw_status & (IRQ_EN_MASK | IRQ_SDIO);
> @@ -958,11 +970,11 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>                 dev_dbg(host->dev,
>                         "Unexpected IRQ! irq_en 0x%08lx - status 0x%08x\n",
>                          IRQ_EN_MASK | IRQ_SDIO, raw_status);
> -               return IRQ_NONE;
> +               goto out_unlock;
>         }
>
>         if (WARN_ON(!host))
> -               return IRQ_NONE;
> +               goto out_unlock;

This part looks like it now becomes incorrectly redundant, since we
are now using "host->mmc" a few lines above while calling
__meson_mmc_sdio_irq_is_enabled().

Maybe move the new code below this part instead?

>
>         /* ack all raised interrupts */
>         writel(status, host->regs + SD_EMMC_STATUS);
> @@ -970,17 +982,16 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>         cmd = host->cmd;
>
>         if (status & IRQ_SDIO) {
> -               spin_lock(&host->lock);
> -               __meson_mmc_enable_sdio_irq(host->mmc, 0);
>                 sdio_signal_irq(host->mmc);
> -               spin_unlock(&host->lock);
>                 status &= ~IRQ_SDIO;
> -               if (!status)
> +               if (!status) {
> +                       spin_unlock(&host->lock);
>                         return IRQ_HANDLED;
> +               }
>         }
>
>         if (WARN_ON(!cmd))
> -               return IRQ_NONE;
> +               goto out_unlock;
>
>         cmd->error = 0;
>         if (status & IRQ_CRC_ERR) {
> @@ -1023,6 +1034,11 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>         if (ret == IRQ_HANDLED)
>                 meson_mmc_request_done(host->mmc, cmd->mrq);
>
> +out_unlock:
> +       if (irq_enabled)
> +               __meson_mmc_enable_sdio_irq(host->mmc, 1);
> +       spin_unlock(&host->lock);
> +
>         return ret;
>  }
>

Kind regards
Uffe