From a022c1e13c01d88edd3436c291630d4b8c642787 Mon Sep 17 00:00:00 2001
From: Stephen Warren <swarren@nvidia.com>
Date: Thu, 24 Apr 2014 17:52:40 -0600
Subject: [PATCH] usb: ums: use only 1 buffer for CI_UDC

ci_udc.c allocates only a single buffer for each endpoint, which
ci_ep_alloc_request() returns as a hard-coded value rather than
dynamically allocating. Consequently, storage_common.c must limit
itself to using a single buffer at a time. Add a special case
to the definition of FSG_NUM_BUFFERS for this.

Another option would be to fix ci_ep_alloc_request() to dynamically
allocate the buffers like some/all(?) other device mode drivers do.
However, I don't think that ci_ep_queue() supports queueing up
multiple buffers either yet, and I'm not familiar enough with the
controller yet to implement that. As such, any attempt to use multiple
buffers simply results in data corruption and other errors.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
---
 drivers/usb/gadget/storage_common.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/usb/gadget/storage_common.c b/drivers/usb/gadget/storage_common.c
index 02803df23c5..74300746b9d 100644
--- a/drivers/usb/gadget/storage_common.c
+++ b/drivers/usb/gadget/storage_common.c
@@ -311,7 +311,11 @@ static struct fsg_lun *fsg_lun_from_dev(struct device *dev)
 #define DELAYED_STATUS	(EP0_BUFSIZE + 999)	/* An impossibly large value */
 
 /* Number of buffers we will use.  2 is enough for double-buffering */
+#ifndef CONFIG_CI_UDC
 #define FSG_NUM_BUFFERS	2
+#else
+#define FSG_NUM_BUFFERS	1 /* ci_udc only allows 1 req per ep at present */
+#endif
 
 /* Default size of buffer length. */
 #define FSG_BUFLEN	((u32)16384)
-- 
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