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Commit be18a251 authored by Per Forlin's avatar Per Forlin Committed by Felipe Balbi
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usb: musb: ux500: optimize DMA callback routine 



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: default avatarPer Forlin <per.forlin@linaro.org>
Acked-by: default avatarMian Yousaf Kaukab <mian.yousaf.kaukab@stericsson.com>
Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
parent dc47ce90

drivers/usb/musb/ux500_dma.c

+3 −36
Original line number Diff line number Diff line
@@ -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;
@@ -56,31 +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;



	dev_dbg(musb->controller, "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;
@@ -94,14 +73,7 @@ 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,
@@ -330,7 +302,6 @@ 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) ||
@@ -347,7 +318,6 @@ 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++) {
@@ -374,15 +344,12 @@ 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;

	}