linux-kernel - Re: [PATCH v2 2/7] mmc: sdhci-of-arasan: Fix SDHCI_RESET

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Date:   Wed, 19 Oct 2022 14:59:39 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Brian Norris <briannorris@...omium.org>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Shawn Lin <shawn.lin@...k-chips.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Fabio Estevam <festevam@...il.com>,
        Haibo Chen <haibo.chen@....com>,
        Broadcom internal kernel review list 
        <bcm-kernel-feedback-list@...adcom.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Florian Fainelli <f.fainelli@...il.com>,
        Michal Simek <michal.simek@...inx.com>,
        Faiz Abbas <faiz_abbas@...com>, linux-mmc@...r.kernel.org,
        Jonathan Hunter <jonathanh@...dia.com>,
        Al Cooper <alcooperx@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        Sowjanya Komatineni <skomatineni@...dia.com>,
        linux-kernel@...r.kernel.org,
        Thierry Reding <thierry.reding@...il.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Sascha Hauer <s.hauer@...gutronix.de>, stable@...r.kernel.org
Subject: Re: [PATCH v2 2/7] mmc: sdhci-of-arasan: Fix SDHCI_RESET_ALL for
 CQHCI

On 10/19/22 14:54, Brian Norris wrote:
> SDHCI_RESET_ALL resets will reset the hardware CQE state, but we aren't
> tracking that properly in software. When out of sync, we may trigger
> various timeouts.
> 
> It's not typical to perform resets while CQE is enabled, but one
> particular case I hit commonly enough: mmc_suspend() -> mmc_power_off().
> Typically we will eventually deactivate CQE (cqhci_suspend() ->
> cqhci_deactivate()), but that's not guaranteed -- in particular, if
> we perform a partial (e.g., interrupted) system suspend.
> 
> The same bug was already found and fixed for two other drivers, in v5.7
> and v5.9:
> 
> 5cf583f1fb9c mmc: sdhci-msm: Deactivate CQE during SDHC reset
> df57d73276b8 mmc: sdhci-pci: Fix SDHCI_RESET_ALL for CQHCI for Intel GLK-based controllers
> 
> The latter is especially prescient, saying "other drivers using CQHCI
> might benefit from a similar change, if they also have CQHCI reset by
> SDHCI_RESET_ALL."
> 
> So like these other patches, deactivate CQHCI when resetting the
> controller.
> 
> Fixes: 84362d79f436 ("mmc: sdhci-of-arasan: Add CQHCI support for arasan,sdhci-5.1")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Brian Norris <briannorris@...omium.org>
> ---
> 
> Changes in v2:
>   - Rely on cqhci_deactivate() to safely handle (ignore)
>     not-yet-initialized CQE support
> 
>   drivers/mmc/host/sdhci-of-arasan.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/mmc/host/sdhci-of-arasan.c b/drivers/mmc/host/sdhci-of-arasan.c
> index 3997cad1f793..b30f0d6baf5b 100644
> --- a/drivers/mmc/host/sdhci-of-arasan.c
> +++ b/drivers/mmc/host/sdhci-of-arasan.c
> @@ -366,6 +366,9 @@ static void sdhci_arasan_reset(struct sdhci_host *host, u8 mask)
>   	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>   	struct sdhci_arasan_data *sdhci_arasan = sdhci_pltfm_priv(pltfm_host);
>   
> +	if ((host->mmc->caps2 & MMC_CAP2_CQE) && (mask & SDHCI_RESET_ALL))
> +		cqhci_deactivate(host->mmc);
> +
>   	sdhci_reset(host, mask);

Cannot this be absorbed by sdhci_reset() that all of these drivers 
appear to be utilizing since you have access to the host and the mask to 
make that decision?
-- 
Florian