Re: [PATCH] ALSA: hda-intel - Disable MSI support by default

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Takashi Iwai wrote:
At Wed, 15 Nov 2006 14:15:45 -0500,
Jeff Garzik wrote:
ACK the pci_intx() calls, NAK the obviously overweight spinlock changes. The spinlock changes are completely unnecessary. Just look at any other (non-ALSA) PCI driver. Existing "spin_lock()" is fine for both PCI shared irq handlers and MSI irq handlers.

It sounds like you are trying to work around a reentrancy problem that does not exist.

Only weird drivers like ps2kbd/mouse or IDE need spin_lock_irqsave(), where separate interrupt sources call the same function.

OK, I revised it, also referring to a similar patch by Yinghai.
I think we can simplify the change like below.
Olivier, could you test this patch, too?

Applied to 2.6.19-rc6, the module tries MSI but this time no IRQ get disabled. The result is equivalent to 2.6.19-rc6


ALSA sound/pci/hda/hda_intel.c:543: hda_intel: No response from codec, disabling MSI...
hda_codec: Unknown model for AD1988, trying auto-probe from BIOS...


Full details:
http://olivn.trollprod.com/19-rc6/19-rc6-takashi-routeirq1.dmesg
http://olivn.trollprod.com/19-rc6/19-rc6-takashi-routeirq1.irq

Olivier




(Here the first chunk (enable_msi=1) is just for testing.
 The patch isn't for merge yet.)


Takashi

---
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
index e35cfd3..130ee12 100644
--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -55,7 +55,7 @@ static char *model;
 static int position_fix;
 static int probe_mask = -1;
 static int single_cmd;
-static int enable_msi;
+static int enable_msi = 1;
module_param(index, int, 0444);
 MODULE_PARM_DESC(index, "Index value for Intel HD audio interface.");
@@ -1380,7 +1380,8 @@ static int __devinit azx_init_stream(str
static int azx_acquire_irq(struct azx *chip, int do_disconnect)
 {
-	if (request_irq(chip->pci->irq, azx_interrupt, IRQF_DISABLED|IRQF_SHARED,
+	if (request_irq(chip->pci->irq, azx_interrupt,
+			chip->msi ? 0 : IRQF_SHARED,
 			"HDA Intel", chip)) {
 		printk(KERN_ERR "hda-intel: unable to grab IRQ %d, "
 		       "disabling device\n", chip->pci->irq);
@@ -1389,6 +1390,7 @@ static int azx_acquire_irq(struct azx *c
 		return -1;
 	}
 	chip->irq = chip->pci->irq;
+	pci_intx(chi->pci, !chip->msi);
 	return 0;
 }


--
Laudator temporis acti (Horace, 173)
Donner c'est donner, repeindre ses volets
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