linux-kernel - [PATCH V2] scsi: ufs: core: Let delay value after LPM can be modified by vendor

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Date:   Fri, 21 Oct 2022 09:52:17 +0800
From:   Zhe Wang <zhewang116@...il.com>
To:     jejb@...ux.ibm.com, martin.petersen@...cle.com,
        alim.akhtar@...sung.com, avri.altman@....com, bvanassche@....org
Cc:     linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        beanhuo@...ron.com, stanley.chu@...iatek.com,
        adrian.hunter@...el.com, zhe.wang1@...soc.com,
        zhenxiong.lai@...soc.com, yuelin.tang@...soc.com
Subject: [PATCH V2] scsi: ufs: core: Let delay value after LPM can be modified by vendor

From: Zhe Wang <zhe.wang1@...soc.com>

Some UFS devices require that the VCC should drop below 0.1V after
turning off, otherwise device may not resume successfully. And
because the power-off rate is different on different SOC platforms.
Therefore, we hope that the delay can be modified by vendor to
adjust the most appropriate delay value.

Signed-off-by: Zhe Wang <zhe.wang1@...soc.com>
---
V1 -> V2
- move turnoff_delay_us to struct ufs_vreg instead
- replace usleep_range with ufshcd_delay_us

 drivers/ufs/core/ufshcd.c | 9 ++++++++-
 include/ufs/ufs.h         | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 7256e6c43ca6..386ff6ed2f20 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -89,6 +89,9 @@
 /* Polling time to wait for fDeviceInit */
 #define FDEVICEINIT_COMPL_TIMEOUT 1500 /* millisecs */
 
+/* Default value of turn off VCC rail: 5000us */
+#define UFS_VCC_TURNOFF_DELAY_US 5000
+
 #define ufshcd_toggle_vreg(_dev, _vreg, _on)				\
 	({                                                              \
 		int _ret;                                               \
@@ -7784,6 +7787,10 @@ static int ufs_get_device_desc(struct ufs_hba *hba)
 
 	ufs_fixup_device_setup(hba);
 
+	if (hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM &&
+	    !hba->vreg_info.vcc->turnoff_delay_us)
+		hba->vreg_info.vcc->turnoff_delay_us = UFS_VCC_TURNOFF_DELAY_US;
+
 	ufshcd_wb_probe(hba, desc_buf);
 
 	ufshcd_temp_notif_probe(hba, desc_buf);
@@ -8918,7 +8925,7 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba *hba)
 	 */
 	if (vcc_off && hba->vreg_info.vcc &&
 		hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM)
-		usleep_range(5000, 5100);
+		ufshcd_delay_us(hba->vreg_info.vcc->turnoff_delay_us, 100);
 }
 
 #ifdef CONFIG_PM
diff --git a/include/ufs/ufs.h b/include/ufs/ufs.h
index 1bba3fead2ce..792335dfd70b 100644
--- a/include/ufs/ufs.h
+++ b/include/ufs/ufs.h
@@ -569,6 +569,7 @@ struct ufs_vreg {
 	bool always_on;
 	bool enabled;
 	int max_uA;
+	u32 turnoff_delay_us;
 };
 
 struct ufs_vreg_info {
-- 
2.17.1