scsi: ufs-mediatek: Do not gate clocks if auto-hibern8 is not entered yet

There is a chance that link enters hibern8 via 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.

Link: https://lore.kernel.org/r/20200601104646.15436-3-stanley.chu@mediatek.com
Reviewed-by: Andy Teng <andy.teng@mediatek.com>
Signed-off-by: Stanley Chu <stanley.chu@mediatek.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufs-mediatek.c b/drivers/scsi/ufs/ufs-mediatek.c
index 523ee55739212ad257776b86366a229e339102e7..3c85f5e97dea87e256b9196e40485c1b5b238de9 100644 (file)
--- 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);