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 multiple saa7164 chips are in use. A reported example can be found here: http://permalink.gmane.org/gmane.linux.drivers.video-input-infrastructure/83948 Reviewed-by: Steven Toth <st...@kernellabs.com> Signed-off-by: Brendan McGrath <red...@redmandi.dyndns.org> --- Changes since v3: * Added link to reported incident in comments * Added Reviewed-by tag from Steven Toth * Used git send-mail (as my patch got mangled using Thunderbird) * Added the linux-kernel mailing list to the recipient list Note I have not included the Tested-by tag from Kyle Sanderson as his test was on v1 (which did not include the module option 'enable_msi') - although much of the code in v3 was there is v1. drivers/media/pci/saa7164/saa7164-core.c | 40 ++++++++++++++++++++++++++++++-- drivers/media/pci/saa7164/saa7164.h | 1 + 2 files changed, 39 insertions(+), 2 deletions(-) diff --git a/drivers/media/pci/saa7164/saa7164-core.c b/drivers/media/pci/saa7164/saa7164-core.c index 4b0bec3..c9a6447 100644 --- a/drivers/media/pci/saa7164/saa7164-core.c +++ b/drivers/media/pci/saa7164/saa7164-core.c @@ -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); @@ -1230,8 +1235,34 @@ static int saa7164_initdev(struct pci_dev *pci_dev, goto fail_irq; } - err = request_irq(pci_dev->irq, saa7164_irq, - IRQF_SHARED, dev->name, dev); + /* irq bit */ + if (enable_msi) + err = pci_enable_msi(pci_dev); + + if (!err && enable_msi) { + /* 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); + } else { + dev->msi = true; + } + } + + if ((!enable_msi) || err) { + dev->msi = false; + /* 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); @@ -1441,6 +1472,11 @@ 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; + } + mutex_lock(&devlist); list_del(&dev->devlist); mutex_unlock(&devlist); diff --git a/drivers/media/pci/saa7164/saa7164.h b/drivers/media/pci/saa7164/saa7164.h index cd1a07c..6df4b252 100644 --- a/drivers/media/pci/saa7164/saa7164.h +++ b/drivers/media/pci/saa7164/saa7164.h @@ -459,6 +459,7 @@ struct saa7164_dev { /* Interrupt status and ack registers */ u32 int_status; u32 int_ack; + u32 msi; struct cmd cmds[SAA_CMD_MAX_MSG_UNITS]; struct mutex lock; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
