RE: [PATCH v3 2/2] scsi: ufs-qcom: enter and exit hibern8 during clock scaling

[Pedro Sousa]

Hi Asutosh,

Please check comments.

-----Original Message-----
From: Asutosh Das <asutoshd@xxxxxxxxxxxxxx> 
Sent: Wednesday, October 23, 2019 5:49 PM
To: cang@xxxxxxxxxxxxxx; rnayak@xxxxxxxxxxxxxx; vinholikatti@xxxxxxxxx; jejb@xxxxxxxxxxxxxxxxxx; martin.petersen@xxxxxxxxxx
Cc: linux-scsi@xxxxxxxxxxxxxxx; kernel-team@xxxxxxxxxxx; saravanak@xxxxxxxxxx; salyzyn@xxxxxxxxxx; Asutosh Das <asutoshd@xxxxxxxxxxxxxx>; Andy Gross <agross@xxxxxxxxxx>; Alim Akhtar <alim.akhtar@xxxxxxxxxxx>; Avri Altman <avri.altman@xxxxxxx>; Pedro Sousa <pedrom.sousa@xxxxxxxxxxxx>; James E.J. Bottomley <jejb@xxxxxxxxxxxxx>; open list:ARM/QUALCOMM SUPPORT <linux-arm-msm@xxxxxxxxxxxxxxx>; open list <linux-kernel@xxxxxxxxxxxxxxx>
Subject: [PATCH v3 2/2] scsi: ufs-qcom: enter and exit hibern8 during clock scaling

Qualcomm controller needs to be in hibern8 before scaling clocks.
This change puts the controller in hibern8 state before scaling
and brings it out after scaling of clocks.

Signed-off-by: Asutosh Das <asutoshd@xxxxxxxxxxxxxx>
---
 drivers/scsi/ufs/ufs-qcom.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/ufs/ufs-qcom.c b/drivers/scsi/ufs/ufs-qcom.c
index a5b7148..55b1de5 100644
--- a/drivers/scsi/ufs/ufs-qcom.c
+++ b/drivers/scsi/ufs/ufs-qcom.c
@@ -1305,18 +1305,27 @@ static int ufs_qcom_clk_scale_notify(struct ufs_hba *hba,
 	int err = 0;
 
 	if (status == PRE_CHANGE) {
+		err = ufshcd_uic_hibern8_enter(hba);
+		if (err)
+			return err;
 		if (scale_up)
 			err = ufs_qcom_clk_scale_up_pre_change(hba);
 		else
 			err = ufs_qcom_clk_scale_down_pre_change(hba);
+		if (err)
+			ufshcd_uic_hibern8_exit(hba);
+
 	} else {
 		if (scale_up)
 			err = ufs_qcom_clk_scale_up_post_change(hba);
 		else
 			err = ufs_qcom_clk_scale_down_post_change(hba);
 
-		if (err || !dev_req_params)
+
+		if (err || !dev_req_params) {
+			ufshcd_uic_hibern8_exit(hba);
 			goto out;
+		}
 
 		ufs_qcom_cfg_timers(hba,
 				    dev_req_params->gear_rx,
@@ -1324,6 +1333,7 @@ static int ufs_qcom_clk_scale_notify(struct ufs_hba *hba,
 				    dev_req_params->hs_rate,
 				    false);
 		ufs_qcom_update_bus_bw_vote(host);
+		ufshcd_uic_hibern8_exit(hba);

Here you are creating the possibility of returning a success even if hibern8 exit fails.
If hibern8 exit fails the ufs recovery will be triggered and "err" variable will not get updated 
in this function, how is this handled? Did you tested this possibility?

 	}
 
 out:
-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

This is just a doubt, it might make sense in this use case, please give me your thoughts.

Thank you,
Pedro Sousa