At Fri, 12 Jun 2015 02:08:50 +0000, Lin, Mengdong wrote:
-----Original Message----- From: Takashi Iwai [mailto:tiwai@suse.de] Sent: Wednesday, June 10, 2015 6:26 PM
Currently snd-hda-intel driver aborts the probing of Intel HD-audio controller with i915 power well management when binding with i915 driver via hda_i915_init() fails. This is no big problem for Haswell and Broadwell where the HD-audio controllers are dedicated to HDMI/DP, thus i915 link is mandatory. However, Skylake, Baytrail and Braswell have only one controller and both HDMI/DP and analog codecs share the same bus. Thus, even if HDMI/DP isn't usable, we should keep the controller working for other codecs.
For fixing this, this patch simply allows continuing the probing even if hda_i915_init() call fails. This may leave stale sound components for HDMI/DP devices that are unbound with graphics. We could abort the probing selectively, but from the code simplicity POV, it's better to continue in all cases.
Reported-by: Libin Yang libin.yang@intel.com Signed-off-by: Takashi Iwai tiwai@suse.de
This is for 4.1. Appying to 4.2 may result in trivial conflicts.
sound/pci/hda/hda_intel.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c index fea198c58196..8a0af6770e1d 100644 --- a/sound/pci/hda/hda_intel.c +++ b/sound/pci/hda/hda_intel.c @@ -1855,7 +1855,7 @@ static int azx_probe_continue(struct azx *chip) #ifdef CONFIG_SND_HDA_I915 err = hda_i915_init(hda); if (err < 0)
goto out_free;
goto skip_i915;@@ -1865,6 +1865,7 @@ static int azx_probe_continue(struct azx *chip) #endif }
- skip_i915: err = azx_first_init(chip); if (err < 0) goto out_free;
-- 2.4.3
Thanks for your patch. But maybe we should not skip i915 for the dedicated display HD-A controller on Haswell/Broadwell.
For HSW/BDW, their HD-A controller for display audio (PCI dev#3) is *partly* in GPU power domain:
- Its PCI configuration space is out of i915 power well, but in an always-on
power well. So even if the BIOS disables the Intel GPU (PCI dev#2), the HD-A controller is still present, and we can still access all standard registers in PCI config space.
Right, and changing this doesn't break things.
- Its audio functions are in the i915 power well. If hda_i915_init() fails and
I915 power well is unavailable, read/write to the audio register of the Controller will fail and we'll get kernel error messages. So I feel it's better to abort if hda_i915_init() fails for this HD-A controller.
By skipping, the access to i915 power well won't happen later, since the component ops isn't set.
I tested Haswell machines with nomodeset to simulate the situation, and there was no any kernel errors except for the first one indicating the failure of i915 binding.
I haven't tested Broadwell, though.
thanks,
Takashi