linux-kernel - [PATCH] usb: chipidea: add loop timeout for hw_ep_set

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Message-ID: <20210809112048.GA3319230@ubuntu>
Date:   Mon, 9 Aug 2021 20:20:48 +0900
From:   Jeaho Hwang <jhhwang@...t.co.kr>
To:     Peter Chen <peter.chen@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH] usb: chipidea: add loop timeout for hw_ep_set_halt()

If ctrl EP priming is failed (very rare case in standard linux),
hw_ep_set_halt goes infinite loop. 50 was enough for zynq7000.

Signed-off-by: Jeaho Hwang <jhhwang@...t.co.kr>
---
 drivers/usb/chipidea/udc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
index d0cd1de1b6c7..92ca0b7e4310 100644
--- a/drivers/usb/chipidea/udc.c
+++ b/drivers/usb/chipidea/udc.c
@@ -210,6 +210,9 @@ static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
 	return 0;
 }
 
+/*will it be enough?*/
+#define HW_EP_SET_HALT_COUNT_MAX 100
+
 /**
  * hw_ep_set_halt: configures ep halt & resets data toggle after clear (execute
  *                 without interruption)
@@ -222,6 +225,7 @@ static int hw_ep_prime(struct ci_hdrc *ci, int num, int dir, int is_ctrl)
  */
 static int hw_ep_set_halt(struct ci_hdrc *ci, int num, int dir, int value)
 {
+	int count = HW_EP_SET_HALT_COUNT_MAX;
 	if (value != 0 && value != 1)
 		return -EINVAL;
 
@@ -233,9 +237,9 @@ static int hw_ep_set_halt(struct ci_hdrc *ci, int num, int dir, int value)
 		/* data toggle - reserved for EP0 but it's in ESS */
 		hw_write(ci, reg, mask_xs|mask_xr,
 			  value ? mask_xs : mask_xr);
-	} while (value != hw_ep_get_halt(ci, num, dir));
+	} while (value != hw_ep_get_halt(ci, num, dir) && --count > 0);
 
-	return 0;
+	return count ? 0 : -EAGAIN;
 }
 
 /**
-- 
2.25.1