linux-kernel - [PATCH v5 1/1] ucsi_ccg: Check DEV

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Date:   Wed, 12 Jan 2022 17:41:43 +0800
From:   Wayne Chang <waynec@...dia.com>
To:     <heikki.krogerus@...ux.intel.com>, <gregkh@...uxfoundation.org>
CC:     <linux-kernel@...r.kernel.org>, <linux-usb@...r.kernel.org>,
        <singhanc@...dia.com>, <waynec@...dia.com>,
        <stable@...r.kernel.org>
Subject: [PATCH v5 1/1] ucsi_ccg: Check DEV_INT bit only when starting CCG4

From: Sing-Han Chen <singhanc@...dia.com>

CCGx clears Bit 0:Device Interrupt in the INTR_REG
if CCGx is reset successfully. However, there might
be a chance that other bits in INTR_REG are not
cleared due to internal data queued in PPM. This case
misleads the driver that CCGx reset failed.

The commit checks bit 0 in INTR_REG and ignores other
bits. The ucsi driver would reset PPM later.

Fixes: 247c554a14aa ("usb: typec: ucsi: add support for Cypress CCGx")
Cc: stable@...r.kernel.org
Signed-off-by: Sing-Han Chen <singhanc@...dia.com>
Signed-off-by: Wayne Chang <waynec@...dia.com>
---
V4 -> V5: Added Cc tag and revised the commit messages
V3 -> V4: Updated the Fixes tag
V2 -> V3: Added the Fixes tag
V1 -> V2: Fixed the name of Sign-off-by
 drivers/usb/typec/ucsi/ucsi_ccg.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c
index bff96d64dddf..6db7c8ddd51c 100644
--- a/drivers/usb/typec/ucsi/ucsi_ccg.c
+++ b/drivers/usb/typec/ucsi/ucsi_ccg.c
@@ -325,7 +325,7 @@ static int ucsi_ccg_init(struct ucsi_ccg *uc)
 		if (status < 0)
 			return status;
 
-		if (!data)
+		if (!(data & DEV_INT))
 			return 0;
 
 		status = ccg_write(uc, CCGX_RAB_INTR_REG, &data, sizeof(data));
-- 
2.25.1