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

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Message-ID: <fedda473-3233-4dfa-e2a3-3f22c2b894e8@gmail.com>
Date:   Mon, 14 Nov 2022 22:33:27 +0100
From:   Heiner Kallweit <hkallweit1@...il.com>
To:     Peter Suti <peter.suti@...eamunlimited.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Neil Armstrong <neil.armstrong@...aro.org>,
        Kevin Hilman <khilman@...libre.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     linux-mmc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mmc: meson-gx: fix SDIO interrupt handling

On 14.11.2022 10:38, Peter Suti 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.
> 

IIRC I had a similar/same problem in mind when discussing the following:
https://lore.kernel.org/linux-arm-kernel/CAPDyKFoameOb7d3cn8_ki1O6DbMEAFvkQh1uUsYp4S-Lkq41oQ@mail.gmail.com/
Not sure though whether it's related to the issue you're facing.

> Fixes: 066ecde ("mmc: meson-gx: add SDIO interrupt support")
> 
> Signed-off-by: Peter Suti <peter.suti@...eamunlimited.com>
> ---
>  drivers/mmc/host/meson-gx-mmc.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/host/meson-gx-mmc.c b/drivers/mmc/host/meson-gx-mmc.c
> index 6e5ea0213b47..972024d57d1c 100644
> --- a/drivers/mmc/host/meson-gx-mmc.c
> +++ b/drivers/mmc/host/meson-gx-mmc.c
> @@ -950,6 +950,10 @@ static irqreturn_t meson_mmc_irq(int irq, void *dev_id)
>  	struct mmc_command *cmd;
>  	u32 status, raw_status;
>  	irqreturn_t ret = IRQ_NONE;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&host->lock, flags);

Typically you wouldn't have to use _irqsave version in a hard irq handler.
Or is to deal with forced threaded irq handlers?
Do you use forced threaded handlers on your system?

> +	__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 +962,11 @@ 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;
>  
>  	/* ack all raised interrupts */
>  	writel(status, host->regs + SD_EMMC_STATUS);
> @@ -970,17 +974,16 @@ 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_irqrestore(&host->lock, flags);
>  			return IRQ_HANDLED;
> +		}
>  	}
>  
>  	if (WARN_ON(!cmd))
> -		return IRQ_NONE;
> +		goto out_unlock;
>  
>  	cmd->error = 0;
>  	if (status & IRQ_CRC_ERR) {
> @@ -1023,6 +1026,10 @@ 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:
> +	__meson_mmc_enable_sdio_irq(host->mmc, 1);
> +	spin_unlock_irqrestore(&host->lock, flags);
> +
>  	return ret;
>  }
>