Hi Robert/Felipie
On Thu, Aug 2, 2012 at 1:41 PM, Roger Quadros <rogerq@xxxxxx> wrote:
>
> Do not rely on any hints from gadget drivers and use DMA mode 1
> whenever we expect more data than the endpoint's packet size and
> have not yet received a short packet.
>
> The last packet if short is always transferred using DMA mode 0.
>
> This patch fixes USB throughput issues in mass storage mode for
> host to device transfers.
>
> Signed-off-by: Roger Quadros <rogerq@xxxxxx>
> ---
> drivers/usb/musb/musb_gadget.c | 30 ++++--------------------------
> 1 files changed, 4 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
> index f7194cf..9c94655 100644
> --- a/drivers/usb/musb/musb_gadget.c
> +++ b/drivers/usb/musb/musb_gadget.c
> @@ -707,12 +707,11 @@ static void rxstate(struct musb *musb, struct musb_request *req)
> len = musb_readw(epio, MUSB_RXCOUNT);
>
> /*
> - * Enable Mode 1 on RX transfers only when short_not_ok flag
> - * is set. Currently short_not_ok flag is set only from
> - * file_storage and f_mass_storage drivers
> + * use mode 1 only if we expect data larger than ep packet_sz
> + * and we have not yet received a short packet
> */
> -
> - if (request->short_not_ok && len == musb_ep->packet_sz)
> + if ((request->length - request->actual > musb_ep->packet_sz) &&
> + (len >= musb_ep->packet_sz))
If the request length is 512 it can go in mode. Please add that while pushing.
> use_mode_1 = 1;
> else
> use_mode_1 = 0;
> @@ -727,27 +726,6 @@ static void rxstate(struct musb *musb, struct musb_request *req)
> c = musb->dma_controller;
> channel = musb_ep->dma;
>
> - /* We use DMA Req mode 0 in rx_csr, and DMA controller operates in
> - * mode 0 only. So we do not get endpoint interrupts due to DMA
> - * completion. We only get interrupts from DMA controller.
> - *
> - * We could operate in DMA mode 1 if we knew the size of the tranfer
> - * in advance. For mass storage class, request->length = what the host
> - * sends, so that'd work. But for pretty much everything else,
> - * request->length is routinely more than what the host sends. For
> - * most these gadgets, end of is signified either by a short packet,
> - * or filling the last byte of the buffer. (Sending extra data in
> - * that last pckate should trigger an overflow fault.) But in mode 1,
> - * we don't get DMA completion interrupt for short packets.
> - *
> - * Theoretically, we could enable DMAReq irq (MUSB_RXCSR_DMAMODE = 1),
> - * to get endpoint interrupt on every DMA req, but that didn't seem
> - * to work reliably.
> - *
> - * REVISIT an updated g_file_storage can set req->short_not_ok, which
> - * then becomes usable as a runtime "use mode 1" hint...
> - */
> -
> /* Experimental: Mode1 works with mass storage use cases */
> if (use_mode_1) {
> csr |= MUSB_RXCSR_AUTOCLEAR;
> --
> 1.7.4.1
>
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