linux-kernel - [PATCH v1 1/2] scsi: ufs: disable irq before disabling clocks

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Date:   Sat, 7 Dec 2019 20:22:00 +0800
From:   Stanley Chu <stanley.chu@...iatek.com>
To:     <linux-scsi@...r.kernel.org>, <martin.petersen@...cle.com>,
        <avri.altman@....com>, <alim.akhtar@...sung.com>,
        <pedrom.sousa@...opsys.com>, <jejb@...ux.ibm.com>,
        <matthias.bgg@...il.com>
CC:     <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <beanhuo@...ron.com>,
        <kuohong.wang@...iatek.com>, <peter.wang@...iatek.com>,
        <chun-hung.wu@...iatek.com>, <andy.teng@...iatek.com>,
        Stanley Chu <stanley.chu@...iatek.com>
Subject: [PATCH v1 1/2] scsi: ufs: disable irq before disabling clocks

During suspend flow, interrupt shall be disabled before disabling
clocks to avoid potential system hang due to accessing host registers
after host clocks are disabled.

For example, if an interrupt comes with IRQF_IRQPOLL flag configured
with the misrouted interrupt recovery feature enabled, ufshcd ISR may
be triggered even if nothing shall be done for UFS. In this case, system
hang may happen if UFS interrupt status register is accessed with host
clocks disabled.

Signed-off-by: Stanley Chu <stanley.chu@...iatek.com>
---
 drivers/scsi/ufs/ufshcd.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index b5966faf3e98..f80bd4e811cb 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -7908,6 +7908,11 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 	ret = ufshcd_vops_suspend(hba, pm_op);
 	if (ret)
 		goto set_link_active;
+	/*
+	 * Disable the host irq as host controller as there won't be any
+	 * host controller transaction expected till resume.
+	 */
+	ufshcd_disable_irq(hba);
 
 	if (!ufshcd_is_link_active(hba))
 		ufshcd_setup_clocks(hba, false);
@@ -7917,11 +7922,7 @@ static int ufshcd_suspend(struct ufs_hba *hba, enum ufs_pm_op pm_op)
 
 	hba->clk_gating.state = CLKS_OFF;
 	trace_ufshcd_clk_gating(dev_name(hba->dev), hba->clk_gating.state);
-	/*
-	 * Disable the host irq as host controller as there won't be any
-	 * host controller transaction expected till resume.
-	 */
-	ufshcd_disable_irq(hba);
+
 	/* Put the host controller in low power mode if possible */
 	ufshcd_hba_vreg_set_lpm(hba);
 	goto out;
-- 
2.18.0