linux-kernel - Re: [PATCH RESEND v2] scsi: ufs: clear doorbell for hibern8 errors when using ah8

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Message-ID: <ce88a8c47d46acd43b3645a3b97ab956@codeaurora.org>
Date:   Thu, 21 Oct 2021 14:10:19 +0800
From:   Can Guo <cang@...eaurora.org>
To:     Kiwoong Kim <kwmad.kim@...sung.com>
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        alim.akhtar@...sung.com, avri.altman@....com, jejb@...ux.ibm.com,
        martin.petersen@...cle.com, beanhuo@...ron.com,
        adrian.hunter@...el.com, sc.suh@...sung.com, hy50.seo@...sung.com,
        sh425.lee@...sung.com, bhoon95.kim@...sung.com,
        vkumar.1997@...sung.com
Subject: Re: [PATCH RESEND v2] scsi: ufs: clear doorbell for hibern8 errors
 when using ah8

On 2021-10-19 12:57, Kiwoong Kim wrote:
> Changes from v1:
> * Change the time to requeue pended commands
> 
> When an scsi command is dispatched right after host complete
> all the pended requests and ufs driver tries to ring a doorbell,
> host might be still during entering into hibern8.
> If the hibern8 error occurrs during that period, the doorbell
> might not be zero and clearing it should have done.
> But, current ufshcd_err_handler goes directly to reset
> w/o clearing the doorbell when the driver's link state is broken.

         /*
          * Stop the host controller and complete the requests
          * cleared by h/w
          */
         ufshcd_hba_stop(hba);
         hba->silence_err_logs = true;
         ufshcd_complete_requests(hba);

Same ask as Adrian did, ufshcd_hba_stop() should clear all doorbell
bits as it disables UFS host controller, then ufshcd_complete_requests()
completes any pending requests, no?

> This patch is to requeue pended commands after host reset.
> 
> Here's an actual symptom that I've faced. At the time, tag #17
> is still pended even after host reset. And then the block timer
> is expired.
> 
> exynos-ufs 11100000.ufs: ufshcd_check_errors: Auto Hibern8
> Enter failed - status: 0x00000040, upmcrs: 0x00000001
> ..
> host_regs: 00000050: b8671000 00000008 00020000 00000000
> ..
> exynos-ufs 11100000.ufs: ufshcd_abort: Device abort task at tag 17
> 
> Signed-off-by: Kiwoong Kim <kwmad.kim@...sung.com>
> ---
>  drivers/scsi/ufs/ufshcd.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index 9faf02c..e5d4ef7 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -7136,8 +7136,10 @@ static int ufshcd_host_reset_and_restore(struct
> ufs_hba *hba)
>  	err = ufshcd_hba_enable(hba);
> 
>  	/* Establish the link again and restore the device */
> -	if (!err)
> +	if (!err) {
> +		ufshcd_retry_aborted_requests(hba);
>  		err = ufshcd_probe_hba(hba, false);
> +	}
> 
>  	if (err)
>  		dev_err(hba->dev, "%s: Host init failed %d\n", __func__, err);