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Subject[PATCH v1 2/3] scsi: ufs-mediatek: Do not gate clocks if auto-hibern8 is not entered yet
Date
There are some chances that link enters hibern8 lately by auto-hibern8
scheme during the clock-gating flow. Clocks shall not be gated if link
is still active otherwise host or device may hang.

Fix this by returning error code to the caller __ufshcd_setup_clocks()
to skip gating clocks there if link is not confirmed in hibern8
state yet.

Also allow some waiting time for the hibern8 state transition.

Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Reviewed-by: Andy Teng <andy.teng@mediatek.com>
---
drivers/scsi/ufs/ufs-mediatek.c | 36 ++++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
index 523ee5573921..3c85f5e97dea 100644
--- a/drivers/scsi/ufs/ufs-mediatek.c
+++ b/drivers/scsi/ufs/ufs-mediatek.c
@@ -178,15 +178,30 @@ static void ufs_mtk_setup_ref_clk_wait_us(struct ufs_hba *hba,
host->ref_clk_ungating_wait_us = ungating_us;
}

-static u32 ufs_mtk_link_get_state(struct ufs_hba *hba)
+int ufs_mtk_wait_link_state(struct ufs_hba *hba, u32 state,
+ unsigned long max_wait_ms)
{
+ ktime_t timeout, time_checked;
u32 val;

- ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
- val = ufshcd_readl(hba, REG_UFS_PROBE);
- val = val >> 28;
+ timeout = ktime_add_us(ktime_get(), ms_to_ktime(max_wait_ms));
+ do {
+ time_checked = ktime_get();
+ ufshcd_writel(hba, 0x20, REG_UFS_DEBUG_SEL);
+ val = ufshcd_readl(hba, REG_UFS_PROBE);
+ val = val >> 28;
+
+ if (val == state)
+ return 0;

- return val;
+ /* Sleep for max. 200us */
+ usleep_range(100, 200);
+ } while (ktime_before(time_checked, timeout));
+
+ if (val == state)
+ return 0;
+
+ return -ETIMEDOUT;
}

/**
@@ -221,10 +236,13 @@ static int ufs_mtk_setup_clocks(struct ufs_hba *hba, bool on,
* triggered by Auto-Hibern8.
*/
if (!ufshcd_can_hibern8_during_gating(hba) &&
- ufshcd_is_auto_hibern8_enabled(hba) &&
- ufs_mtk_link_get_state(hba) ==
- VS_LINK_HIBERN8)
- ufs_mtk_setup_ref_clk(hba, on);
+ ufshcd_is_auto_hibern8_enabled(hba)) {
+ ret = ufs_mtk_wait_link_state(hba,
+ VS_LINK_HIBERN8,
+ 15);
+ if (!ret)
+ ufs_mtk_setup_ref_clk(hba, on);
+ }
}
} else if (on && status == POST_CHANGE) {
ret = phy_power_on(host->mphy);
--
2.18.0
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