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usb: musb: host: don't program dma for zero byte tx

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

Signed-off-by: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
This commit is contained in:
Ajay Kumar Gupta 2012-07-20 11:07:22 +05:30 committed by Felipe Balbi
parent f0443afd1d
commit 3132122c66
1 changed files with 11 additions and 1 deletions
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12
drivers/usb/musb/musb_host.c
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@ -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(