linux-kernel - [PATCH v2 1/2] usb: musb: Fix DMA for host mode

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Date:	Mon, 8 Feb 2016 15:15:29 -0700
From:	Joshua Henderson <joshua.henderson@...rochip.com>
To:	<linux-kernel@...r.kernel.org>
CC:	Cristian Birsan <cristian.birsan@...rochip.com>,
	Joshua Henderson <joshua.henderson@...rochip.com>,
	Felipe Balbi <balbi@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>
Subject: [PATCH v2 1/2] usb: musb: Fix DMA for host mode

From: Cristian Birsan <cristian.birsan@...rochip.com>

Commit ac33cdb16681 ("usb: musb: Remove ifdefs for musb_host_rx in
musb_host.c part5") introduces a problem setting DMA host mode.

This commit fixes the done condition that advances the musb schedule.
Without this patch the the msub_advance_schedule() is called immediately
after receiving an endpoint rx interrupt without waiting for the dma
transfer to complete. As a consequence when the dma complete interrupt
arrives the in_qh member of hw_ep is already null an the musb_host_rx()
exits on !urb error case.

Signed-off-by: Cristian Birsan <cristian.birsan@...rochip.com>
Signed-off-by: Joshua Henderson <joshua.henderson@...rochip.com>
---
Changes since v1:
	- Don't add unecessary new variable. Just correct done.
---
 drivers/usb/musb/musb_host.c |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 795a45b..6bef86f 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -2006,9 +2006,15 @@ void musb_host_rx(struct musb *musb, u8 epnum)
 			done = musb_rx_dma_in_inventra_cppi41(c, hw_ep, qh,
 							      urb, xfer_len,
 							      iso_err);
-			if (done)
+			if (done) {
+				/* Don't call msub_advance_schedule()
+				 * immediately after receiving an endpoint RX
+				 * interrupt without waiting for the DMA
+				 * transfer to complete.
+				 */
+				done = false;
 				goto finish;
-			else
+			} else
 				dev_err(musb->controller, "error: rx_dma failed\n");
 		}
 
-- 
1.7.9.5