[PATCH v1 3/7] scsi: ufs-mediatek: Prevent host hang by setting CLK_CG early

From: Stanley Chu
Date: Wed Jun 22 2022 - 03:37:46 EST


From: Peter Wang <peter.wang@xxxxxxxxxxxx>

Some UFSHCI hosts in MediaTek UFS platform need workaround
to prevent host hang issue by setting CLK_CG bit before
host is enabled.

This operation shall have no side effect on those platforms
which do not support this bit.

Reviewed-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
Signed-off-by: Peter Wang <peter.wang@xxxxxxxxxxxx>
Signed-off-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>
---
drivers/ufs/host/ufs-mediatek.c | 8 ++++++++
drivers/ufs/host/ufs-mediatek.h | 1 +
2 files changed, 9 insertions(+)

diff --git a/drivers/ufs/host/ufs-mediatek.c b/drivers/ufs/host/ufs-mediatek.c
index f76e2999ac99..d6b2734e7f81 100755
--- a/drivers/ufs/host/ufs-mediatek.c
+++ b/drivers/ufs/host/ufs-mediatek.c
@@ -183,6 +183,14 @@ static int ufs_mtk_hce_enable_notify(struct ufs_hba *hba,
hba->capabilities &= ~MASK_AUTO_HIBERN8_SUPPORT;
hba->ahit = 0;
}
+
+ /*
+ * Turn on CLK_CG early to bypass abnormal ERR_CHK signal
+ * to prevent host hang issue
+ */
+ ufshcd_writel(hba,
+ ufshcd_readl(hba, REG_UFS_XOUFS_CTRL) | 0x80,
+ REG_UFS_XOUFS_CTRL);
}

return 0;
diff --git a/drivers/ufs/host/ufs-mediatek.h b/drivers/ufs/host/ufs-mediatek.h
index 49a2137fb251..f5c1c643dd52 100755
--- a/drivers/ufs/host/ufs-mediatek.h
+++ b/drivers/ufs/host/ufs-mediatek.h
@@ -12,6 +12,7 @@
/*
* Vendor specific UFSHCI Registers
*/
+#define REG_UFS_XOUFS_CTRL 0x140
#define REG_UFS_REFCLK_CTRL 0x144
#define REG_UFS_EXTREG 0x2100
#define REG_UFS_MPHYCTRL 0x2200
--
2.18.0