linux-kernel - Re: [RFC PATCH v1] ufs: poll HCS.UCRDY before issuing a UIC command

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Date:   Wed, 10 May 2023 11:53:52 -0700
From:   Bart Van Assche <bvanassche@....org>
To:     Kiwoong Kim <kwmad.kim@...sung.com>, 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, kwangwon.min@...sung.com
Subject: Re: [RFC PATCH v1] ufs: poll HCS.UCRDY before issuing a UIC command

On 5/9/23 01:24, Kiwoong Kim wrote:
> With auto hibern8 enabled, UIC could be working
> for a while to process a hibern8 operation and HCI
> reports UIC not ready for a short term through HCS.UCRDY.
> And UFS driver can't recognize the operation.
> UFSHCI spec specifies UCRDY like this:
> whether the host controller is ready to process UIC COMMAND
> 
> The 'ready' could be seen as many different meanings. If the meaning
> includes not processing any request from HCI, processing a hibern8
> operation can be 'not ready'. In this situation, the driver needs to
> wait until the operations is completed.
> 
> Signed-off-by: Kiwoong Kim <kwmad.kim@...sung.com>
> ---
>   drivers/ufs/core/ufshcd.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 96ce6af..fc79539 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2368,7 +2368,18 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
>    */
>   static inline bool ufshcd_ready_for_uic_cmd(struct ufs_hba *hba)
>   {
> -	return ufshcd_readl(hba, REG_CONTROLLER_STATUS) & UIC_COMMAND_READY;
> +	ktime_t timeout = ktime_add_ms(ktime_get(), UIC_CMD_TIMEOUT);
> +	u32 val = 0;
> +
> +	do {
> +		val = ufshcd_readl(hba, REG_CONTROLLER_STATUS) &
> +			UIC_COMMAND_READY;
> +		if (val)
> +			break;
> +		usleep_range(500, 1000);
> +	} while (ktime_before(ktime_get(), timeout));
> +
> +	return val ? true : false;
>   }
>   
>   /**

Reviewed-by: Bart Van Assche <bvanassche@....org>