[PATCH v2 2/2] scsi: ufs: core: Retry the full device init on fatal link loss

[Shawn Lin]

On an RK3572 board the UFS device is sometimes reported dead during the
initialization at boot: DEVICE_FATAL_ERROR | UIC_LINK_LOST is latched and
the following UIC query fails with -EIO, leaving the device unusable.

Recover by resetting the device and the controller and redoing the whole
initialization sequence, up to three times with a 100 ms settle delay in
between. Doing this in ufshcd_init() rather than in the platform driver's
probe keeps the interrupt, clock and regulator resources acquired only
once, and the UFS device is already reachable through hba->priv at that
point.

Each retry stops a pending error handler and clears the error state
latched by the failed attempt, reconfigures and re-enables MCQ if the
controller reset cleared it, and restores the reset ufshcd_state, so
that no stale error context survives into the retried initialization.

Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>

---

Changes in v2:
- Move the initialization sequence into a new function and retry by
  looping over its call site instead of adding more gotos to
  ufshcd_init()(Bart)
- Stop a pending error handler and clear the error state latched by the
  failed attempt, so that the retry starts from a clean state(sashiko)
- Reconfigure and re-enable MCQ after the controller re-enable, since
  the HCE toggle clears the MCQ mode setting(sashiko)

 drivers/ufs/core/ufshcd.c | 46 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 45 insertions(+), 1 deletion(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index f1e54d719537..bd82d6755739 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -11468,8 +11468,52 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 
 	/* Initialize hba, detect and initialize UFS device */
 	ktime_t probe_start = ktime_get();
+	int retries = 3;
 
-	err = ufshcd_full_device_init(hba);
+	while (retries--) {
+		unsigned long flags;
+
+		err = ufshcd_full_device_init(hba);
+		if (!err)
+			break;
+
+		if (!retries)
+			break;
+
+		dev_warn(hba->dev, "UFS init failed %d, full retry (%d left)\n",
+			 err, retries);
+
+		/*
+		 * The failed attempt may have latched fatal errors and
+		 * scheduled the error handler. Stop it and start the retry
+		 * from a clean state, mirroring ufshcd_reset_and_restore().
+		 */
+		cancel_work_sync(&hba->eh_work);
+		spin_lock_irqsave(hba->host->host_lock, flags);
+		hba->saved_err = 0;
+		hba->saved_uic_err = 0;
+		hba->force_reset = false;
+		hba->ufshcd_state = UFSHCD_STATE_RESET;
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+		ufshcd_device_reset(hba);
+		ufs_put_device_desc(hba);
+		ufshcd_hba_stop(hba);
+		if (ufshcd_hba_enable(hba)) {
+			dev_err(hba->dev, "Host controller enable failed\n");
+			ufshcd_print_evt_hist(hba);
+			ufshcd_print_host_state(hba);
+			goto out_release;
+		}
+
+		/* Reconfigure MCQ upon controller re-enable */
+		if (hba->mcq_enabled) {
+			ufshcd_config_mcq(hba);
+			ufshcd_mcq_enable(hba);
+		}
+
+		msleep(100);
+	}
 
 	ufshcd_process_probe_result(hba, probe_start, err);
 	if (err)
-- 
2.25.1