From: Santosh Shilimkar <santosh.shilimkar@xxxxxx> 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@xxxxxx> Signed-off-by: Maulik Mankad <x0082077@xxxxxx> Cc: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> Signed-off-by: Felipe Balbi <balbi@xxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx> --- drivers/usb/musb/musb_host.c | 6 ++++++ 1 files changed, 6 insertions(+), 0 deletions(-) diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c index 877d20b..9e65c47 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); -- 1.7.2 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
