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

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Date:   Wed, 12 Oct 2022 17:09:02 +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
Subject: [PATCH] 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>
---
 drivers/ufs/core/ufshcd.c | 11 +++++++++--
 include/ufs/ufshcd.h      |  2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 7256e6c43ca6..f6350231da0e 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 +7787,9 @@ 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->vcc_turnoff_delay)
+		hba->vcc_turnoff_delay = UFS_VCC_TURNOFF_DELAY_US;
+
 	ufshcd_wb_probe(hba, desc_buf);
 
 	ufshcd_temp_notif_probe(hba, desc_buf);
@@ -8917,8 +8923,9 @@ static void ufshcd_vreg_set_lpm(struct ufs_hba *hba)
 	 * Some UFS devices require delay after VCC power rail is turned-off.
 	 */
 	if (vcc_off && hba->vreg_info.vcc &&
-		hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM)
-		usleep_range(5000, 5100);
+		hba->dev_quirks & UFS_DEVICE_QUIRK_DELAY_AFTER_LPM &&
+		hba->vcc_turnoff_delay)
+		usleep_range(hba->vcc_turnoff_delay, hba->vcc_turnoff_delay + 100);
 }
 
 #ifdef CONFIG_PM
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 9f28349ebcff..bfde3cb962fb 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -828,6 +828,7 @@ struct ufs_hba_monitor {
  *	device
  * @complete_put: whether or not to call ufshcd_rpm_put() from inside
  *	ufshcd_resume_complete()
+ * @vcc_turnoff_delay: VCC turnoff delay value.
  */
 struct ufs_hba {
 	void __iomem *mmio_base;
@@ -975,6 +976,7 @@ struct ufs_hba {
 #endif
 	u32 luns_avail;
 	bool complete_put;
+	u32 vcc_turnoff_delay;
 };
 
 /* Returns true if clocks can be gated. Otherwise false */
-- 
2.17.1