diff options
| author | Ajay Kumar Gupta <ajay.gupta@ti.com> | 2012-07-20 11:07:22 +0530 |
|---|---|---|
| committer | Felipe Balbi <balbi@ti.com> | 2012-08-03 09:34:39 +0300 |
| commit | 3132122c664dd9361e2179e8a388d87ca89ace6c (patch) | |
| tree | 9e10ae98b352461936fb9dbf4e7c47a9a8c3fa8a /drivers/usb/musb | |
| parent | f0443afd1d82b07305df1511a6055311047fdfc6 (diff) | |
| download | blackbird-op-linux-3132122c664dd9361e2179e8a388d87ca89ace6c.tar.gz blackbird-op-linux-3132122c664dd9361e2179e8a388d87ca89ace6c.zip | |
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: Ajay Kumar Gupta <ajay.gupta@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb/musb')
| -rw-r--r-- | drivers/usb/musb/musb_host.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/usb/musb/musb_host.c b/drivers/usb/musb/musb_host.c index 4bb717d0bd41..29b5149f5756 100644 --- a/drivers/usb/musb/musb_host.c +++ b/drivers/usb/musb/musb_host.c @@ -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( |
