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authorSantosh Shilimkar <santosh.shilimkar@ti.com>2010-09-20 10:32:07 +0300
committerGreg Kroah-Hartman <gregkh@suse.de>2010-09-24 11:05:01 -0700
commit4c647338267e14c93892f6f125f17ea2419eea51 (patch)
treeb2a03caa8bcb245933bcce943adbafe66d73e059 /drivers/usb/musb
parent66af83ddf7b5a4ea94e79cbeadaa0aeed4def5f7 (diff)
usb: musb: host: Issue a memory barrier before starting DMA
This patch fixes the issue which was observed while transfering a large file ( > 20MB) over USB (OMAP MUSB controller acts as USB host) to an attached USB thumb drive. It was found that CDB field of CBW packet was set to 0x0. This was due to missing a barrier before DMA engine starts transfer. This buffer is allocated using dma_alloc_coherent which gives non-cacheble but bufferable memory and hence needed a write memory barrier to flush the write buffer. More info on this thread is here: http://www.spinics.net/lists/linux-omap/msg33987.html Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com> Signed-off-by: Maulik Mankad <x0082077@ti.com> Cc: Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: Felipe Balbi <balbi@ti.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/usb/musb')
-rw-r--r--drivers/usb/musb/musb_host.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c
index 877d20b1dff..9e65c47cc98 100644
--- a/drivers/usb/musb/musb_host.c
+++ b/drivers/usb/musb/musb_host.c
@@ -660,6 +660,12 @@ static bool musb_tx_dma_program(struct dma_controller *dma,
qh->segsize = length;
+ /*
+ * Ensure the data reaches to main memory before starting
+ * DMA transfer
+ */
+ wmb();
+
if (!dma->channel_program(channel, pkt_size, mode,
urb->transfer_dma + offset, length)) {
dma->channel_release(channel);