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

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>
Link: https://lore.kernel.org/r/20240724135126.1786126-1-vamshigajjela@google.com
Fixes: cad2e03 ("ufs: add support to allow non standard behaviours (quirks)")
Cc: stable@vger.kernel.org
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

Author: Vamshi Gajjela

drivers/ufs/core/ufshcd.c

@@ -4100,11 +4100,16 @@ 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();
 }
 
 /**