linux-kernel - [PATCH 3.10 052/139] usb: renesas_usbhs: fix usbhsf_fifo

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Message-Id: <1509571600-4858-3-git-send-email-w@1wt.eu>
Date:   Wed,  1 Nov 2017 22:25:53 +0100
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
        Felipe Balbi <felipe.balbi@...ux.intel.com>,
        Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 052/139] usb: renesas_usbhs: fix usbhsf_fifo_clear() for RX direction

From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>

commit 0a2ce62b61f2c76d0213edf4e37aaf54a8ddf295 upstream.

This patch fixes an issue that the usbhsf_fifo_clear() is possible
to cause 10 msec delay if the pipe is RX direction and empty because
the FRDY bit will never be set to 1 in such case.

Fixes: e8d548d54968 ("usb: renesas_usbhs: fifo became independent from pipe.")
Cc: <stable@...r.kernel.org> 
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Signed-off-by: Felipe Balbi <felipe.balbi@...ux.intel.com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/usb/renesas_usbhs/fifo.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/renesas_usbhs/fifo.c b/drivers/usb/renesas_usbhs/fifo.c
index 47a6ffa..0c962ff 100644
--- a/drivers/usb/renesas_usbhs/fifo.c
+++ b/drivers/usb/renesas_usbhs/fifo.c
@@ -263,8 +263,17 @@ static void usbhsf_fifo_clear(struct usbhs_pipe *pipe,
 	struct usbhs_priv *priv = usbhs_pipe_to_priv(pipe);
 	int ret = 0;
 
-	if (!usbhs_pipe_is_dcp(pipe))
-		ret = usbhsf_fifo_barrier(priv, fifo);
+	if (!usbhs_pipe_is_dcp(pipe)) {
+		/*
+		 * This driver checks the pipe condition first to avoid -EBUSY
+		 * from usbhsf_fifo_barrier() with about 10 msec delay in
+		 * the interrupt handler if the pipe is RX direction and empty.
+		 */
+		if (usbhs_pipe_is_dir_in(pipe))
+			ret = usbhs_pipe_is_accessible(pipe);
+		if (!ret)
+			ret = usbhsf_fifo_barrier(priv, fifo);
+	}
 
 	/*
 	 * if non-DCP pipe, this driver should set BCLR when
-- 
2.8.0.rc2.1.gbe9624a