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Commit 0ae52d54 authored by Anand Gadiyar's avatar Anand Gadiyar Committed by Felipe Balbi
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usb: musb: Enable DMA mode1 RX for transfers without short packets 



This patch enables DMA mode1 for the RX path when we know
there won't be any short packets. We check that by looking
into the short_no_ok flag, if it's true we enable mode1, otherwise
we use mode0 to transfer the data.

This will result in a throughput performance gain of around
40% for USB mass-storage/mtp use cases.

[ balbi@ti.com : updated commit log and code comments slightly ]

Signed-off-by: default avatarAnand Gadiyar <gadiyar@ti.com>
Signed-off-by: default avatarMoiz Sonasath <m-sonasath@ti.com>
Signed-off-by: default avatarVikram Pandita <vikram.pandita@ti.com>
Tested-by: default avatarVikram Pandita <vikram.pandita@ti.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent b3c3dc22

drivers/usb/musb/musb_gadget.c

+43 −26
Original line number Diff line number Diff line
@@ -634,6 +634,7 @@ static void rxstate(struct musb *musb, struct musb_request *req) 
	u16			len;

	u16			csr = musb_readw(epio, MUSB_RXCSR);

	struct musb_hw_ep	*hw_ep = &musb->endpoints[epnum];

	u8			use_mode_1;



	if (hw_ep->is_shared_fifo)

		musb_ep = &hw_ep->ep_in;
@@ -683,6 +684,18 @@ static void rxstate(struct musb *musb, struct musb_request *req) 


	if (csr & MUSB_RXCSR_RXPKTRDY) {

		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

		 */



		if (request->short_not_ok && len == musb_ep->packet_sz)

			use_mode_1 = 1;

		else

			use_mode_1 = 0;



		if (request->actual < request->length) {

#ifdef CONFIG_USB_INVENTRA_DMA

			if (is_buffer_mapped(req)) {
@@ -714,37 +727,41 @@ static void rxstate(struct musb *musb, struct musb_request *req) 
	 * then becomes usable as a runtime "use mode 1" hint...

	 */



				csr |= MUSB_RXCSR_DMAENAB;

#ifdef USE_MODE1

				/* Experimental: Mode1 works with mass storage use cases */

				if (use_mode_1) {

					csr |= MUSB_RXCSR_AUTOCLEAR;

				/* csr |= MUSB_RXCSR_DMAMODE; */

					musb_writew(epio, MUSB_RXCSR, csr);

					csr |= MUSB_RXCSR_DMAENAB;

					musb_writew(epio, MUSB_RXCSR, csr);



				/* this special sequence (enabling and then

					/*

					 * this special sequence (enabling and then

					 * disabling MUSB_RXCSR_DMAMODE) is required

					 * to get DMAReq to activate

					 */

					musb_writew(epio, MUSB_RXCSR,

						csr | MUSB_RXCSR_DMAMODE);

#else

					musb_writew(epio, MUSB_RXCSR, csr);



				} else {

					if (!musb_ep->hb_mult &&

						musb_ep->hw_ep->rx_double_buffered)

						csr |= MUSB_RXCSR_AUTOCLEAR;

#endif

					csr |= MUSB_RXCSR_DMAENAB;

					musb_writew(epio, MUSB_RXCSR, csr);

				}



				if (request->actual < request->length) {

					int transfer_size = 0;

#ifdef USE_MODE1

					if (use_mode_1) {

						transfer_size = min(request->length - request->actual,

								channel->max_len);

#else

						musb_ep->dma->desired_mode = 1;

					} else {

						transfer_size = min(request->length - request->actual,

								(unsigned)len);

#endif

					if (transfer_size <= musb_ep->packet_sz)

						musb_ep->dma->desired_mode = 0;

					else

						musb_ep->dma->desired_mode = 1;

					}



					use_dma = c->channel_program(

							channel,