From: Per Forlin per.forlin@linaro.org

Skip the use of work queue and call musb_dma_completion() directly from DMA callback context.

Here follows measurements on a Snowball board with ondemand governor active.

Performance using work queue: (105 MB) copied, 6.23758 s, 16.8 MB/s (105 MB) copied, 5.7151 s, 18.3 MB/s (105 MB) copied, 5.83583 s, 18.0 MB/s (105 MB) copied, 5.93611 s, 17.7 MB/s

Performance without work queue (105 MB) copied, 5.62173 s, 18.7 MB/s (105 MB) copied, 5.61811 s, 18.7 MB/s (105 MB) copied, 5.57817 s, 18.8 MB/s (105 MB) copied, 5.58549 s, 18.8 MB/s

Signed-off-by: Per Forlin per.forlin@linaro.org Acked-by: Mian Yousaf Kaukab mian.yousaf.kaukab@stericsson.com --- Change log. v2: remove cast for void pointer v3: rebase patch on top of a pure 3.1-rc1

drivers/usb/musb/ux500_dma.c | 38 +++----------------------------------- 1 files changed, 3 insertions(+), 35 deletions(-)

diff --git a/drivers/usb/musb/ux500_dma.c b/drivers/usb/musb/ux500_dma.c index cecace4..6f10bba 100644 --- a/drivers/usb/musb/ux500_dma.c +++ b/drivers/usb/musb/ux500_dma.c @@ -37,7 +37,6 @@ struct ux500_dma_channel { struct dma_channel channel; struct ux500_dma_controller *controller; struct musb_hw_ep *hw_ep; - struct work_struct channel_work; struct dma_chan *dma_chan; unsigned int cur_len; dma_cookie_t cookie; @@ -56,30 +55,11 @@ struct ux500_dma_controller { dma_addr_t phy_base; };

-/* Work function invoked from DMA callback to handle tx transfers. */ -static void ux500_tx_work(struct work_struct *data) -{ - struct ux500_dma_channel *ux500_channel = container_of(data, - struct ux500_dma_channel, channel_work); - struct musb_hw_ep *hw_ep = ux500_channel->hw_ep; - struct musb *musb = hw_ep->musb; - unsigned long flags; - - DBG(4, "DMA tx transfer done on hw_ep=%d\n", hw_ep->epnum); - - spin_lock_irqsave(&musb->lock, flags); - ux500_channel->channel.actual_len = ux500_channel->cur_len; - ux500_channel->channel.status = MUSB_DMA_STATUS_FREE; - musb_dma_completion(musb, hw_ep->epnum, - ux500_channel->is_tx); - spin_unlock_irqrestore(&musb->lock, flags); -} - /* Work function invoked from DMA callback to handle rx transfers. */ -static void ux500_rx_work(struct work_struct *data) +void ux500_dma_callback(void *private_data) { - struct ux500_dma_channel *ux500_channel = container_of(data, - struct ux500_dma_channel, channel_work); + struct dma_channel *channel = private_data; + struct ux500_dma_channel *ux500_channel = channel->private_data; struct musb_hw_ep *hw_ep = ux500_channel->hw_ep; struct musb *musb = hw_ep->musb; unsigned long flags; @@ -92,14 +72,7 @@ static void ux500_rx_work(struct work_struct *data) musb_dma_completion(musb, hw_ep->epnum, ux500_channel->is_tx); spin_unlock_irqrestore(&musb->lock, flags); -} - -void ux500_dma_callback(void *private_data) -{ - struct dma_channel *channel = (struct dma_channel *)private_data; - struct ux500_dma_channel *ux500_channel = channel->private_data;

- schedule_work(&ux500_channel->channel_work); }

static bool ux500_configure_channel(struct dma_channel *channel, @@ -326,7 +299,6 @@ static int ux500_dma_controller_start(struct dma_controller *c) void **param_array; struct ux500_dma_channel *channel_array; u32 ch_count; - void (*musb_channel_work)(struct work_struct *); dma_cap_mask_t mask;

if ((data->num_rx_channels > UX500_MUSB_DMA_NUM_RX_CHANNELS) || @@ -343,7 +315,6 @@ static int ux500_dma_controller_start(struct dma_controller *c) channel_array = controller->rx_channel; ch_count = data->num_rx_channels; param_array = data->dma_rx_param_array; - musb_channel_work = ux500_rx_work;

for (dir = 0; dir < 2; dir++) { for (ch_num = 0; ch_num < ch_count; ch_num++) { @@ -370,15 +341,12 @@ static int ux500_dma_controller_start(struct dma_controller *c) return -EBUSY; }

- INIT_WORK(&ux500_channel->channel_work, - musb_channel_work); }

/* Prepare the loop for TX channels */ channel_array = controller->tx_channel; ch_count = data->num_tx_channels; param_array = data->dma_tx_param_array; - musb_channel_work = ux500_tx_work; is_tx = 1; }