[PATCH 2/2] scsi: ufs: core: Fix the code for entering hibernation

[Bart Van Assche <bvanassche@acm.org>]

Accessing a host controller register after the host controller has
entered the hibernation state may cause the host controller to exit the
hibernation state. Hence rework the hibernation entry code such that it
does not modify the interrupt enabled status. This patch relies on the
following:
* If an UIC command is submitted that should be completed by the UIC
  command completion interrupt, hba->uic_async_done == NULL.
* If an UIC command is submitted that should be completed by the power
  mode change interrupt or by a hibernation state change interrupt,
  hba->uic_async_done != NULL.

Signed-off-by: Bart Van Assche <bvanassche@acm.org>
---
 drivers/ufs/core/ufshcd.c | 22 ++++++----------------
 include/ufs/ufshcd.h      |  7 ++++---
 2 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
index d0ae6e50becc..e12f30b8a83c 100644
--- a/drivers/ufs/core/ufshcd.c
+++ b/drivers/ufs/core/ufshcd.c
@@ -2585,6 +2585,7 @@ int ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
 	ufshcd_hold(hba);
 	mutex_lock(&hba->uic_cmd_mutex);
 	ufshcd_add_delay_before_dme_cmd(hba);
+	WARN_ON(hba->uic_async_done);
 
 	ret = __ufshcd_send_uic_cmd(hba, uic_cmd, true);
 	if (!ret)
@@ -4255,7 +4256,6 @@ 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);
@@ -4266,15 +4266,6 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
 		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.
-		 */
-		ufshcd_readl(hba, REG_INTERRUPT_ENABLE);
-		reenable_intr = true;
-	}
 	spin_unlock_irqrestore(hba->host->host_lock, flags);
 	ret = __ufshcd_send_uic_cmd(hba, cmd, false);
 	if (ret) {
@@ -4318,8 +4309,6 @@ 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);
@@ -5472,11 +5461,12 @@ static irqreturn_t ufshcd_uic_cmd_compl(struct ufs_hba *hba, u32 intr_status)
 		hba->errors |= (UFSHCD_UIC_HIBERN8_MASK & intr_status);
 
 	if (intr_status & UIC_COMMAND_COMPL && cmd) {
-		cmd->argument2 |= ufshcd_get_uic_cmd_result(hba);
-		cmd->argument3 = ufshcd_get_dme_attr_val(hba);
-		if (!hba->uic_async_done)
+		if (!hba->uic_async_done) {
+			cmd->argument2 |= ufshcd_get_uic_cmd_result(hba);
+			cmd->argument3 = ufshcd_get_dme_attr_val(hba);
 			cmd->cmd_active = 0;
-		complete(&cmd->done);
+			complete(&cmd->done);
+		}
 		retval = IRQ_HANDLED;
 	}
 
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index a43b14276bc3..0577013a4611 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -868,9 +868,10 @@ enum ufshcd_mcq_opr {
  * @tmf_tag_set: TMF tag set.
  * @tmf_queue: Used to allocate TMF tags.
  * @tmf_rqs: array with pointers to TMF requests while these are in progress.
- * @active_uic_cmd: handle of active UIC command
- * @uic_cmd_mutex: mutex for UIC command
- * @uic_async_done: completion used during UIC processing
+ * @active_uic_cmd: active UIC command pointer.
+ * @uic_cmd_mutex: mutex used to serialize UIC command processing.
+ * @uic_async_done: completion used to wait for power mode or hibernation state
+ *	changes.
  * @ufshcd_state: UFSHCD state
  * @eh_flags: Error handling flags
  * @intr_mask: Interrupt Mask Bits