linux-kernel - Re: [PATCH V2 3/5] mmc: mmci: fix clear of busy detect status

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Date:   Mon, 27 May 2019 20:17:05 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Ludovic Barre <ludovic.Barre@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        DTML <devicetree@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        linux-stm32@...md-mailman.stormreply.com
Subject: Re: [PATCH V2 3/5] mmc: mmci: fix clear of busy detect status

On Fri, 26 Apr 2019 at 09:46, Ludovic Barre <ludovic.Barre@...com> wrote:
>
> From: Ludovic Barre <ludovic.barre@...com>
>
> The "busy_detect_flag" is used to read/clear busy value of
> mmci status. The "busy_detect_mask" is used to manage busy irq of
> mmci mask.
> For sdmmc variant, the 2 properties have not the same offset.
> To clear the busyd0 status bit, we must add busy detect flag,
> the mmci mask is not enough.
>
> Signed-off-by: Ludovic Barre <ludovic.barre@...com>

Ludovic, again, apologies for the delay.

> ---
>  drivers/mmc/host/mmci.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
> index a040f54..3cd52e8 100644
> --- a/drivers/mmc/host/mmci.c
> +++ b/drivers/mmc/host/mmci.c
> @@ -1517,7 +1517,8 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
>                  * to make sure that both start and end interrupts are always
>                  * cleared one after the other.
>                  */
> -               status &= readl(host->base + MMCIMASK0);
> +               status &= readl(host->base + MMCIMASK0) |
> +                       host->variant->busy_detect_flag;

I think this is not entirely correct, because it would mean we check
for busy even if we haven't unmasked the busy IRQ via the
variant->busy_detect_mask.

I suggest to store a new bool in the host (call it
"busy_detect_unmasked" or whatever makes sense to you), to track
whether we have unmasked the busy IRQ or not. Then take this flag into
account, before ORing the value of host->variant->busy_detect_flag,
according to above.

>                 if (host->variant->busy_detect)
>                         writel(status & ~host->variant->busy_detect_mask,
>                                host->base + MMCICLEAR);
> --
> 2.7.4
>

Kind regards
Uffe