lkml.org 
[lkml]   [2015]   [Apr]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCHv5] [media] saa7164: use an MSI interrupt when available
Date
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: Steven Toth <stoth@kernellabs.com>
Signed-off-by: Brendan McGrath <redmcg@redmandi.dyndns.org>
---
Changes since v4:
- improved readability by taking on suggestions made by Mauro
- the msi variable in the saa7164_dev structure is now a bool

Thanks Mauro - good suggestions and I think I've taken on board all of them.

drivers/media/pci/saa7164/saa7164-core.c | 66 ++++++++++++++++++++++++++++----
drivers/media/pci/saa7164/saa7164.h | 1 +
2 files changed, 60 insertions(+), 7 deletions(-)

diff --git a/drivers/media/pci/saa7164/saa7164-core.c b/drivers/media/pci/saa7164/saa7164-core.c
index 9cf3c6c..5e4a9f0 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);
@@ -1184,6 +1189,39 @@ 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)
{
@@ -1230,13 +1268,22 @@ 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);
- if (err < 0) {
- printk(KERN_ERR "%s: can't get IRQ %d\n", dev->name,
- pci_dev->irq);
- err = -EIO;
- 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);
@@ -1439,6 +1486,11 @@ 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);
diff --git a/drivers/media/pci/saa7164/saa7164.h b/drivers/media/pci/saa7164/saa7164.h
index cd1a07c..75a3f51 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;
+ bool msi;

struct cmd cmds[SAA_CMD_MAX_MSG_UNITS];
struct mutex lock;
--
1.9.1


\
 
 \ /
  Last update: 2015-04-10 09:21    [W:0.105 / U:1.628 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site