[PATCH] scsi: ufs: core: Fix hba->last_dme_cmd_tstamp timestamp updating logic

[PATCH] scsi: ufs: core: Fix hba->last_dme_cmd_tstamp timestamp updating logic

[Vamshi Gajjela]

The ufshcd_add_delay_before_dme_cmd() always introduces a delay of
MIN_DELAY_BEFORE_DME_CMDS_US between DME commands even when it's not
required. The delay is added when the UFS host controller supplies the
quirk UFSHCD_QUIRK_DELAY_BEFORE_DME_CMDS.

Fix the logic to update hba->last_dme_cmd_tstamp to ensure subsequent
DME commands have the correct delay in the range of 0 to
MIN_DELAY_BEFORE_DME_CMDS_US.

Update the timestamp at the end of the function to ensure it captures
the latest time after any necessary delay has been applied.

Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com>
Fixes: cad2e03d8607 ("ufs: add support to allow non standard behaviours (quirks)")
Cc: stable@vger.kernel.org
---
 drivers/ufs/core/ufshcd.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index dc757ba47522..406bda1585f6 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -4090,11 +4090,16 @@ static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba *hba)
 			min_sleep_time_us =
 				MIN_DELAY_BEFORE_DME_CMDS_US - delta;
 		else
-			return; /* no more delay required */
+			min_sleep_time_us = 0; /* no more delay required */
 	}
 
-	/* allow sleep for extra 50us if needed */
-	usleep_range(min_sleep_time_us, min_sleep_time_us + 50);
+	if (min_sleep_time_us > 0) {
+		/* allow sleep for extra 50us if needed */
+		usleep_range(min_sleep_time_us, min_sleep_time_us + 50);
+	}
+
+	/* update the last_dme_cmd_tstamp */
+	hba->last_dme_cmd_tstamp = ktime_get();
 }
 
 /**
-- 
2.45.2.1089.g2a221341d9-goog

Re: [PATCH] scsi: ufs: core: Fix hba->last_dme_cmd_tstamp timestamp updating logic

[Bart Van Assche]

On 7/24/24 6:51 AM, Vamshi Gajjela wrote:
> The ufshcd_add_delay_before_dme_cmd() always introduces a delay of
> MIN_DELAY_BEFORE_DME_CMDS_US between DME commands even when it's not
> required. The delay is added when the UFS host controller supplies the
> quirk UFSHCD_QUIRK_DELAY_BEFORE_DME_CMDS.
> 
> Fix the logic to update hba->last_dme_cmd_tstamp to ensure subsequent
> DME commands have the correct delay in the range of 0 to
> MIN_DELAY_BEFORE_DME_CMDS_US.
> 
> Update the timestamp at the end of the function to ensure it captures
> the latest time after any necessary delay has been applied.
> 
> Signed-off-by: Vamshi Gajjela <vamshigajjela@google.com>
> Fixes: cad2e03d8607 ("ufs: add support to allow non standard behaviours (quirks)")
> Cc: stable@vger.kernel.org
> ---
>   drivers/ufs/core/ufshcd.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index dc757ba47522..406bda1585f6 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -4090,11 +4090,16 @@ static inline void ufshcd_add_delay_before_dme_cmd(struct ufs_hba *hba)
>   			min_sleep_time_us =
>   				MIN_DELAY_BEFORE_DME_CMDS_US - delta;
>   		else
> -			return; /* no more delay required */
> +			min_sleep_time_us = 0; /* no more delay required */
>   	}
>   
> -	/* allow sleep for extra 50us if needed */
> -	usleep_range(min_sleep_time_us, min_sleep_time_us + 50);
> +	if (min_sleep_time_us > 0) {
> +		/* allow sleep for extra 50us if needed */
> +		usleep_range(min_sleep_time_us, min_sleep_time_us + 50);
> +	}
> +
> +	/* update the last_dme_cmd_tstamp */
> +	hba->last_dme_cmd_tstamp = ktime_get();
>   }

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