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Commit 3132122c authored by Ajay Kumar Gupta's avatar Ajay Kumar Gupta Committed by Felipe Balbi
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usb: musb: host: don't program dma for zero byte tx 



This is to reduce the overhead of dma programming for zero byte
transmit as same can be done using pio mode.

Signed-off-by: default avatarAjay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent f0443afd

drivers/usb/musb/musb_host.c

+11 −1
Original line number Diff line number Diff line
@@ -693,6 +693,8 @@ static void musb_ep_program(struct musb *musb, u8 epnum, 
	void __iomem		*epio = hw_ep->regs;

	struct musb_qh		*qh = musb_ep_get_qh(hw_ep, !is_out);

	u16			packet_sz = qh->maxpacket;

	u8			use_dma = 1;

	u16			csr;



	dev_dbg(musb->controller, "%s hw%d urb %p spd%d dev%d ep%d%s "

				"h_addr%02x h_port%02x bytes %d\n",
@@ -704,9 +706,17 @@ static void musb_ep_program(struct musb *musb, u8 epnum, 


	musb_ep_select(mbase, epnum);



	if (is_out && !len) {

		use_dma = 0;

		csr = musb_readw(epio, MUSB_TXCSR);

		csr &= ~MUSB_TXCSR_DMAENAB;

		musb_writew(epio, MUSB_TXCSR, csr);

		hw_ep->tx_channel = NULL;

	}



	/* candidate for DMA? */

	dma_controller = musb->dma_controller;

	if (is_dma_capable() && epnum && dma_controller) {

	if (use_dma && is_dma_capable() && epnum && dma_controller) {

		dma_channel = is_out ? hw_ep->tx_channel : hw_ep->rx_channel;

		if (!dma_channel) {

			dma_channel = dma_controller->channel_alloc(