Commit 5fb6bc71 authored by Davidlohr Bueso's avatar Davidlohr Bueso Committed by Greg Kroah-Hartman
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staging/most, dim2: convert dim2_tasklet to threaded irq 



Tasklets have long been deprecated as being too heavy on the system
by running in irq context - and this is not a performance critical
path. If a higher priority process wants to run, it must wait for
the tasklet to finish before doing so. A more suitable equivalent
is to converted to threaded irq instead and service channels in
regular task context.

Signed-off-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Link: https://lore.kernel.org/r/20220411151620.129178-2-dave@stgolabs.net


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 88d33bb8

drivers/staging/most/dim2/dim2.c

+9 −20
Original line number Diff line number Diff line
@@ -45,9 +45,6 @@ MODULE_PARM_DESC(fcnt, "Num of frames per sub-buffer for sync channels as a powe 


static DEFINE_SPINLOCK(dim_lock);



static void dim2_tasklet_fn(unsigned long data);

static DECLARE_TASKLET_OLD(dim2_tasklet, dim2_tasklet_fn);



/**

 * struct hdm_channel - private structure to keep channel specific data

 * @name: channel name
@@ -361,15 +358,9 @@ static irqreturn_t dim2_mlb_isr(int irq, void *_dev) 
	return IRQ_HANDLED;

}



/**

 * dim2_tasklet_fn - tasklet function

 * @data: private data

 *

 * Service each initialized channel, if needed

 */

static void dim2_tasklet_fn(unsigned long data)

static irqreturn_t dim2_task_irq(int irq, void *_dev)

{

	struct dim2_hdm *dev = (struct dim2_hdm *)data;

	struct dim2_hdm *dev = _dev;

	unsigned long flags;

	int ch_idx;
@@ -385,6 +376,8 @@ static void dim2_tasklet_fn(unsigned long data) 
		while (!try_start_dim_transfer(dev->hch + ch_idx))

			continue;

	}



	return IRQ_HANDLED;

}



/**
@@ -392,8 +385,8 @@ static void dim2_tasklet_fn(unsigned long data) 
 * @irq: irq number

 * @_dev: private data

 *

 * Acknowledge the interrupt and schedule a tasklet to service channels.

 * Return IRQ_HANDLED.

 * Acknowledge the interrupt and service each initialized channel,

 * if needed, in task context.

 */

static irqreturn_t dim2_ahb_isr(int irq, void *_dev)

{
@@ -405,9 +398,7 @@ static irqreturn_t dim2_ahb_isr(int irq, void *_dev) 
	dim_service_ahb_int_irq(get_active_channels(dev, buffer));

	spin_unlock_irqrestore(&dim_lock, flags);



	dim2_tasklet.data = (unsigned long)dev;

	tasklet_schedule(&dim2_tasklet);

	return IRQ_HANDLED;

	return IRQ_WAKE_THREAD;

}



/**
@@ -654,14 +645,12 @@ static int poison_channel(struct most_interface *most_iface, int ch_idx) 
	if (!hdm_ch->is_initialized)

		return -EPERM;



	tasklet_disable(&dim2_tasklet);

	spin_lock_irqsave(&dim_lock, flags);

	hal_ret = dim_destroy_channel(&hdm_ch->ch);

	hdm_ch->is_initialized = false;

	if (ch_idx == dev->atx_idx)

		dev->atx_idx = -1;

	spin_unlock_irqrestore(&dim_lock, flags);

	tasklet_enable(&dim2_tasklet);

	if (hal_ret != DIM_NO_ERROR) {

		pr_err("HAL Failed to close channel %s\n", hdm_ch->name);

		ret = -EFAULT;
@@ -821,8 +810,8 @@ static int dim2_probe(struct platform_device *pdev) 
		goto err_shutdown_dim;

	}



	ret = devm_request_irq(&pdev->dev, irq, dim2_ahb_isr, 0,

			       "dim2_ahb0_int", dev);

	ret = devm_request_threaded_irq(&pdev->dev, irq, dim2_ahb_isr,

					dim2_task_irq, 0, "dim2_ahb0_int", dev);

	if (ret) {

		dev_err(&pdev->dev, "failed to request ahb0_int irq %d\n", irq);

		goto err_shutdown_dim;