FROMLIST: ufs: ufs-qcom: Fix sequential read variance

The current devfreq downdifferential threshold of 5% causes overly
aggressive frequency downscaling, leading to performance degradation
sometimes during sequential read workloads.

Update the UFS devfreq downdifferential threshold to 65.
This widens the hysteresis window and prevents overly aggressive
downscaling, ensuring that frequency is maintained for loads above 5%
and scaling down occurs only when utilization falls below this level,
while scale-up still triggers above the 70% threshold.

Signed-off-by: Nitin Rawat <nitin.rawat@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Pradeep P V K <pradeep.pragallapati@oss.qualcomm.com>
Link:
https://lore.kernel.org/all/20260122141331.239354-4-nitin.rawat@oss.qualcomm.com/

Author: Pradeep-pvk

drivers/ufs/host/ufs-qcom.c

@@ -1957,7 +1957,7 @@ static void ufs_qcom_config_scaling_param(struct ufs_hba *hba,
 	p->polling_ms = 60;
 	p->timer = DEVFREQ_TIMER_DELAYED;
 	d->upthreshold = 70;
-	d->downdifferential = 5;
+	d->downdifferential = 65;
 
 	hba->clk_scaling.suspend_on_no_request = true;
 }