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Commit 77978089 authored by Brendan McGrath's avatar Brendan McGrath Committed by Mauro Carvalho Chehab
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[media] saa7164: use an MSI interrupt when available 

Enhances driver to use an MSI interrupt when available.

Adds the module option 'enable_msi' (type bool) which by default is
enabled. Can be set to 'N' to disable.

Fixes (or can reduce the occurrence of) a crash which is most commonly
reported when both digital tuners of the saa7164 chip is in use. A
reported example can be found here:
http://permalink.gmane.org/gmane.linux.drivers.video-input-infrastructure/83948



Reviewed-by: default avatarSteven Toth <stoth@kernellabs.com>
Signed-off-by: default avatarBrendan McGrath <redmcg@redmandi.dyndns.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@osg.samsung.com>
parent 4c12adad

drivers/media/pci/saa7164/saa7164-core.c

+59 −7
Original line number Diff line number Diff line
@@ -85,6 +85,11 @@ module_param(guard_checking, int, 0644); 
MODULE_PARM_DESC(guard_checking,

	"enable dma sanity checking for buffer overruns");



static bool enable_msi = true;

module_param(enable_msi, bool, 0444);

MODULE_PARM_DESC(enable_msi,

		"enable the use of an msi interrupt if available");



static unsigned int saa7164_devcount;



static DEFINE_MUTEX(devlist);
@@ -1186,6 +1191,39 @@ static int saa7164_thread_function(void *data) 
	return 0;

}



static bool saa7164_enable_msi(struct pci_dev *pci_dev, struct saa7164_dev *dev)

{

	int err;



	if (!enable_msi) {

		printk(KERN_WARNING "%s() MSI disabled by module parameter 'enable_msi'"

		       , __func__);

		return false;

	}



	err = pci_enable_msi(pci_dev);



	if (err) {

		printk(KERN_ERR "%s() Failed to enable MSI interrupt."

			" Falling back to a shared IRQ\n", __func__);

		return false;

	}



	/* no error - so request an msi interrupt */

	err = request_irq(pci_dev->irq, saa7164_irq, 0,

						dev->name, dev);



	if (err) {

		/* fall back to legacy interrupt */

		printk(KERN_ERR "%s() Failed to get an MSI interrupt."

		       " Falling back to a shared IRQ\n", __func__);

		pci_disable_msi(pci_dev);

		return false;

	}



	return true;

}



static int saa7164_initdev(struct pci_dev *pci_dev,

			   const struct pci_device_id *pci_id)

{
@@ -1232,14 +1270,23 @@ static int saa7164_initdev(struct pci_dev *pci_dev, 
		goto fail_irq;

	}



	/* irq bit */

	if (saa7164_enable_msi(pci_dev, dev)) {

		dev->msi = true;

	} else {

		/* if we have an error (i.e. we don't have an interrupt)

			 or msi is not enabled - fallback to shared interrupt */



		err = request_irq(pci_dev->irq, saa7164_irq,

				IRQF_SHARED, dev->name, dev);



		if (err < 0) {

			printk(KERN_ERR "%s: can't get IRQ %d\n", dev->name,

			       pci_dev->irq);

			err = -EIO;

			goto fail_irq;

		}

	}



	pci_set_drvdata(pci_dev, dev);
@@ -1441,6 +1488,11 @@ static void saa7164_finidev(struct pci_dev *pci_dev) 
	/* unregister stuff */

	free_irq(pci_dev->irq, dev);



	if (dev->msi) {

		pci_disable_msi(pci_dev);

		dev->msi = false;

	}



	pci_disable_device(pci_dev);



	mutex_lock(&devlist);

drivers/media/pci/saa7164/saa7164.h

+1 −0
Original line number Diff line number Diff line
@@ -464,6 +464,7 @@ struct saa7164_dev { 
	/* Interrupt status and ack registers */

	u32 int_status;

	u32 int_ack;

	bool msi;



	struct cmd			cmds[SAA_CMD_MAX_MSG_UNITS];

	struct mutex			lock;