[RFC PATCH v1] ufs: poll pmc until another pa request is completed

[Kiwoong Kim]

Regarding 5.7.12.11 in Unipro v1.8, PA rejects sebsequent
requests following the first request from upper layer or remote.
In this situation, PA responds w/ BUSY in cases
when they come from upper layer and does nothing for
the requests. So HCI doesn't receive ind, a.k.a. indicator
for its requests and an interrupt, IS.UPMS isn't generated.

When LINERESET occurs, the error handler issues PMC which is
recognized as a request for PA. If a host's PA gets or raises
LINERESET, and a request for PMC, this could be a concurrent
situation mentioned above. And I found that situation w/ my
environment.

[  222.929539]I[0:DefaultDispatch:20410] exynos-ufs 13500000.ufs: ufshcd_update_uic_error: uecdl : 0x80000002
[  222.999009]I[0: arch_disk_io_1:20413] exynos-ufs 13500000.ufs: ufshcd_update_uic_error: uecpa : 0x80000010
[  222.999200] [6:  kworker/u16:2:  132] exynos-ufs 13500000.ufs: ufs_pwr_mode_restore_needed : mode = 0x15, pwr_rx = 1, pwr_tx = 1
[  223.002876]I[0: arch_disk_io_3:20422] exynos-ufs 13500000.ufs: ufshcd_update_uic_error: uecpa : 0x80000010
[  223.501050] [4:  kworker/u16:2:  132] exynos-ufs 13500000.ufs: pwr ctrl cmd 0x2 with mode 0x11 completion timeout
[  223.502305] [4:  kworker/u16:2:  132] exynos-ufs 13500000.ufs: ufshcd_change_power_mode: power mode change failed -110
[  223.502312] [4:  kworker/u16:2:  132] exynos-ufs 13500000.ufs: ufshcd_err_handler: Failed to restore power mode, err = -110
[  223.502392] [4:  kworker/u16:2:  132] exynos-ufs 13500000.ufs: ufshcd_is_pwr_mode_restore_needed : mode = 0x11, pwr_rx = 1, pwr_tx = 1

This patch is to poll PMC's result w/o checking its ind until
the result is not busy, i.e. 09h, to avoid the rejection.

Signed-off-by: Kiwoong Kim <kwmad.kim@xxxxxxxxxxx>
---
 drivers/ufs/core/ufshcd.c | 92 ++++++++++++++++++++++++++++++++++-------------
 1 file changed, 67 insertions(+), 25 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index 9434328..3fa58d9 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -98,6 +98,9 @@
 /* Polling time to wait for fDeviceInit */
 #define FDEVICEINIT_COMPL_TIMEOUT 1500 /* millisecs */
 
+/* Polling time to wait until PA is ready */
+#define UIC_PA_RDY_TIMEOUT	30	/* millisecs */
+
 /* UFSHC 4.0 compliant HC support this mode, refer param_set_mcq_mode() */
 static bool use_mcq_mode = true;
 
@@ -4138,6 +4141,64 @@ int ufshcd_dme_get_attr(struct ufs_hba *hba, u32 attr_sel,
 }
 EXPORT_SYMBOL_GPL(ufshcd_dme_get_attr);
 
+static int __ufshcd_poll_uic_pwr(struct ufs_hba *hba, struct uic_command *cmd,
+		struct completion *cnf)
+{
+	unsigned long flags;
+	int ret;
+	ktime_t timeout;
+	u32 mode = cmd->argument3;
+
+	timeout = ktime_add_ms(ktime_get(), UIC_PA_RDY_TIMEOUT);
+	do {
+		spin_lock_irqsave(hba->host->host_lock, flags);
+		hba->active_uic_cmd = NULL;
+		if (ufshcd_is_link_broken(hba)) {
+			spin_unlock_irqrestore(hba->host->host_lock, flags);
+			ret = -ENOLINK;
+			goto out;
+		}
+		hba->uic_async_done = cnf;
+		cmd->argument2 = 0;
+		cmd->argument3 = mode;
+		ret = __ufshcd_send_uic_cmd(hba, cmd, true);
+		spin_unlock_irqrestore(hba->host->host_lock, flags);
+		if (ret) {
+			dev_err(hba->dev,
+				"pwr ctrl cmd 0x%x with mode 0x%x uic error %d\n",
+				cmd->command, cmd->argument3, ret);
+			goto out;
+		}
+
+		/* This value is heuristic */
+		if (!wait_for_completion_timeout(&cmd->done,
+		    msecs_to_jiffies(5))) {
+			ret = -ETIMEDOUT;
+			dev_err(hba->dev,
+				"pwr ctrl cmd 0x%x with mode 0x%x timeout\n",
+				cmd->command, cmd->argument3);
+			if (cmd->cmd_active)
+				goto out;
+
+			dev_info(hba->dev, "%s: pwr ctrl cmd has already been completed\n", __func__);
+		}
+
+		/* retry for only busy cases */
+		ret = cmd->argument2 & MASK_UIC_COMMAND_RESULT;
+		if (ret != UIC_CMD_RESULT_BUSY)
+			break;
+
+		dev_info(hba->dev, "%s: PA is busy and can't handle a requeest\n", __func__);
+
+	} while (ktime_before(ktime_get(), timeout));
+out:
+	spin_lock_irqsave(hba->host->host_lock, flags);
+	hba->active_uic_cmd = NULL;
+	spin_unlock_irqrestore(hba->host->host_lock, flags);
+
+	return ret;
+}
+
 /**
  * ufshcd_uic_pwr_ctrl - executes UIC commands (which affects the link power
  * state) and waits for it to take effect.
@@ -4160,33 +4221,16 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 	unsigned long flags;
 	u8 status;
 	int ret;
-	bool reenable_intr = false;
 
 	mutex_lock(&hba->uic_cmd_mutex);
 	ufshcd_add_delay_before_dme_cmd(hba);
 
-	spin_lock_irqsave(hba->host->host_lock, flags);
-	if (ufshcd_is_link_broken(hba)) {
-		ret = -ENOLINK;
-		goto out_unlock;
-	}
-	hba->uic_async_done = &uic_async_done;
-	if (ufshcd_readl(hba, REG_INTERRUPT_ENABLE) & UIC_COMMAND_COMPL) {
-		ufshcd_disable_intr(hba, UIC_COMMAND_COMPL);
-		/*
-		 * Make sure UIC command completion interrupt is disabled before
-		 * issuing UIC command.
-		 */
-		wmb();
-		reenable_intr = true;
-	}
-	ret = __ufshcd_send_uic_cmd(hba, cmd, false);
-	spin_unlock_irqrestore(hba->host->host_lock, flags);
+	ret = __ufshcd_poll_uic_pwr(hba, cmd, &uic_async_done);
 	if (ret) {
-		dev_err(hba->dev,
-			"pwr ctrl cmd 0x%x with mode 0x%x uic error %d\n",
-			cmd->command, cmd->argument3, ret);
-		goto out;
+		if (ret == -ENOLINK)
+			goto out_unlock;
+		else
+			goto out;
 	}
 
 	if (!wait_for_completion_timeout(hba->uic_async_done,
@@ -4223,14 +4267,12 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	hba->active_uic_cmd = NULL;
 	hba->uic_async_done = NULL;
-	if (reenable_intr)
-		ufshcd_enable_intr(hba, UIC_COMMAND_COMPL);
 	if (ret) {
 		ufshcd_set_link_broken(hba);
 		ufshcd_schedule_eh_work(hba);
 	}
-out_unlock:
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
+out_unlock:
 	mutex_unlock(&hba->uic_cmd_mutex);
 
 	return ret;
-- 
2.7.4