From b431ba8803666e56c1d178a421b3cbc36e8d3d33 Mon Sep 17 00:00:00 2001
From: Bin Liu <b-liu@ti.com>
Date: Mon, 24 Aug 2015 15:28:37 -0500
Subject: [PATCH] usb: musb: fix cppi channel teardown for isoch transfer
After a few iterations of start/stop UVC camera streaming, the streaming
stops.
This patch adds 250us delay in the cppi channel abort path to let cppi
drain properly.
Using 50us delay seems to be too aggressive, some webcams are still
broken. 250us is the original value used in TI 3.2 kernel.
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
drivers/usb/musb/musb_cppi41.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/usb/musb/musb_cppi41.c b/drivers/usb/musb/musb_cppi41.c
index d07cafb7d5f5a..e499b862a946f 100644
--- a/drivers/usb/musb/musb_cppi41.c
+++ b/drivers/usb/musb/musb_cppi41.c
@@ -551,6 +551,9 @@ static int cppi41_dma_channel_abort(struct dma_channel *channel)
} else {
cppi41_set_autoreq_mode(cppi41_channel, EP_MODE_AUTOREQ_NONE);
+ /* delay to drain to cppi dma pipeline for isoch */
+ udelay(250);
+
csr = musb_readw(epio, MUSB_RXCSR);
csr &= ~(MUSB_RXCSR_H_REQPKT | MUSB_RXCSR_DMAENAB);
musb_writew(epio, MUSB_RXCSR, csr);
--
GitLab