linux-kernel - Re: [PATCH v4 3/4] mmc: sdhci-tegra: Issue CMD and DAT resets together

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Message-ID: <df68846a-2a09-ef98-6823-d536d99ccb61@intel.com>
Date:   Tue, 27 Sep 2022 13:23:41 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Prathamesh Shete <pshete@...dia.com>, ulf.hansson@...aro.org,
        thierry.reding@...il.com, jonathanh@...dia.com,
        p.zabel@...gutronix.de, linux-mmc@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     anrao@...dia.com, smangipudi@...dia.com, kyarlagadda@...dia.com
Subject: Re: [PATCH v4 3/4] mmc: sdhci-tegra: Issue CMD and DAT resets
 together

On 27/09/22 13:09, Prathamesh Shete wrote:
> In case of error condition to avoid system crash
> Tegra SDMMC controller requires CMD and DAT resets
> issued together. SDHCI controller FSM goes into
> bad state due to rapid SD card hot-plug event.
> Issuing reset on the CMD FSM before DATA FSM results
> in kernel panic, hence add support to issue CMD and
> DAT resets together.
> This is applicable to Tegra186 and later chips.
> 
> Signed-off-by: Aniruddha TVS Rao <anrao@...dia.com>
> Signed-off-by: Prathamesh Shete <pshete@...dia.com>
> ---
>  drivers/mmc/host/sdhci-tegra.c | 3 ++-
>  drivers/mmc/host/sdhci.c       | 8 +++++++-
>  drivers/mmc/host/sdhci.h       | 2 ++
>  3 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> index 46f37cc26dbb..61dc5ee0726d 100644
> --- a/drivers/mmc/host/sdhci-tegra.c
> +++ b/drivers/mmc/host/sdhci-tegra.c
> @@ -1536,7 +1536,8 @@ static const struct sdhci_pltfm_data sdhci_tegra186_pdata = {
>  		  SDHCI_QUIRK_NO_HISPD_BIT |
>  		  SDHCI_QUIRK_BROKEN_ADMA_ZEROLEN_DESC |
>  		  SDHCI_QUIRK_CAP_CLOCK_BASE_BROKEN,
> -	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN,
> +	.quirks2 = SDHCI_QUIRK2_PRESET_VALUE_BROKEN |
> +		   SDHCI_QUIRK2_ISSUE_CMD_DAT_RESET_TOGETHER,
>  	.ops  = &tegra186_sdhci_ops,
>  };
>  
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 2b5dda521b0e..5123ec3fc74a 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -266,12 +266,14 @@ enum sdhci_reset_reason {
>  	SDHCI_RESET_FOR_TUNING_ABORT,
>  	SDHCI_RESET_FOR_CARD_REMOVED,
>  	SDHCI_RESET_FOR_CQE_RECOVERY,
> +	SDHCI_RESET_FOR_CMD_DAT_TOGETHER,
>  };
>  
>  static void sdhci_reset_for_reason(struct sdhci_host *host, enum sdhci_reset_reason reason)
>  {
>  	switch (reason) {
>  	case SDHCI_RESET_FOR_INIT:
> +	case SDHCI_RESET_FOR_CMD_DAT_TOGETHER:
>  		sdhci_do_reset(host, SDHCI_RESET_CMD | SDHCI_RESET_DATA);
>  		break;
>  	case SDHCI_RESET_FOR_REQUEST_ERROR:
> @@ -3084,7 +3086,11 @@ static bool sdhci_request_done(struct sdhci_host *host)
>  			/* This is to force an update */
>  			host->ops->set_clock(host, host->clock);
>  
> -		sdhci_reset_for(host, REQUEST_ERROR);
> +		if (host->quirks2 &
> +			SDHCI_QUIRK2_ISSUE_CMD_DAT_RESET_TOGETHER)
> +			sdhci_reset_for(host, CMD_DAT_TOGETHER);
> +		else
> +			sdhci_reset_for(host, REQUEST_ERROR);

This is what I am trying to avoid because it is inconsistent.
Consider:
 - why is the quirk needed for some REQUEST_ERRORs but not others?
 - or why is the quirk not needed for all CMD / DAT resets?

So, I was expecting the quirk to be applied in sdhci_reset_for_reason()
not here.

>  
>  		host->pending_reset = false;
>  	}
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index d750c464bd1e..6a5766774b05 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -478,6 +478,8 @@ struct sdhci_host {
>   * block count.
>   */
>  #define SDHCI_QUIRK2_USE_32BIT_BLK_CNT			(1<<18)
> +/* Issue CMD and DATA reset together */
> +#define SDHCI_QUIRK2_ISSUE_CMD_DAT_RESET_TOGETHER	(1<<19)
>  
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */