On Wed, May 12, 2010 at 05:19:38PM +0530, Ajay Kumar Gupta wrote:
> MUSB RTL version 1.8 onward (OMAP3630, AM/DM37x, OMAP4) DMA requires
> the buffers to be aligned on a four byte boundary. This affects USB
> CDC/RNDIS class application where buffers are always unaligned.
>
> Use system DMA for unaligned buffers as a workaround of this issue.
>
> Current patch supports device side CDC/RNDIS. Host side would require
> change in Tx programming path for mode-0 operation when transfer length
> is more than packet size.
>
> Also fixed an issue in device Tx completion path where 'is_dma' is getting
> set unconditionally. This would fail the io if Tx transfer is done in
> mode-0. Fixed it by updating it based on 'request->actual' length.
>
> Signed-off-by: Ajay Kumar Gupta <ajay.gupta@xxxxxx>
[..]
> @@ -166,6 +166,12 @@ config MUSB_USE_SYSTEM_DMA_WORKAROUND
> DMA channels are simultaneously enabled. To work around this issue,
> you can choose to use System DMA for RX channels.
>
> + Also on Mentor DMA in MUSB RTL version 1.8 (OMAP3630, AM/DM37x)
> + requires buffers to be aligned on a four byte boundary. This affects
> + USB CDC/RNDIS class application where buffers are always unaligned.
> + To work around this issue, you can choose to use System DMA for
> + unaligned buffers.
instead of this patch, it's a whole lot easier to simply use a bounce
buffer:
if (unaligned) {
bounce = dma_alloc_coherent(......);
memcpy(request->buf, bounce, request->length);
}
and use that buffer on channel_program();
--
balbi
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