Re: [alsa-devel] commit b1ef29725865 (ACPI _REV=2) causes sound regression on Dell XPS 13 [Was: Discussion around quirking the _REV behavior for the XPS 13 (2015) until 4.2]
On Tuesday, May 12, 2015 10:43:33 AM Matthew Garrett wrote:
On Tue, May 12, 2015 at 10:29 AM, Mario Limonciello mario_limonciello@dell.com wrote:
Just to be clear, from the Dell side only the XPS 13 9343 has this _REV behavior.
The Inspiron 7437 queries _REV and uses it to modify its EC behaviour, and apparently breaks on Linux without that.
What's wrong with a DMI quirk until I2S is mature on the kernel side and userspace is new enough in distros? Is it too early in boot for DMI quirks? That would enforce that no other machines can use _REV value of 5 to detect Linux without breaking the 9343.
DMI quirking is fine, but it has to be behind a config option. We're going to have to carry the quirk for several years because we have to support old userspace for an arbitrarily long time, and if there's no config option then Linux will be stuck in HDA mode for that entire time.
One problem with the DMI-based approach is that _REV is constant in ACPICA, so to be able to return different values from it for different systems, we'll need to add some ACPICA-ish code handling that specifically for Linux and we're a bit too late in the cycle for that.
So here's what I'm going to do. I'll revert commit b1ef29725865 for 4.1, but *only* for 4.1 (I've actually queued up a revert of it already) and I'll revert that revert during the 4.2 merge window.
In the meantime, we'll develop the code to implement the DMI-based quirks for the Dells and apply it for 4.2.
Are there any volunteers for doing the last part?
On Wed, May 13, 2015 at 01:38:59AM +0200, Rafael J. Wysocki wrote:
On Tuesday, May 12, 2015 10:43:33 AM Matthew Garrett wrote:
On Tue, May 12, 2015 at 10:29 AM, Mario Limonciello mario_limonciello@dell.com wrote:
Just to be clear, from the Dell side only the XPS 13 9343 has this _REV behavior.
The Inspiron 7437 queries _REV and uses it to modify its EC behaviour, and apparently breaks on Linux without that.
What's wrong with a DMI quirk until I2S is mature on the kernel side and userspace is new enough in distros? Is it too early in boot for DMI quirks? That would enforce that no other machines can use _REV value of 5 to detect Linux without breaking the 9343.
DMI quirking is fine, but it has to be behind a config option. We're going to have to carry the quirk for several years because we have to support old userspace for an arbitrarily long time, and if there's no config option then Linux will be stuck in HDA mode for that entire time.
One problem with the DMI-based approach is that _REV is constant in ACPICA, so to be able to return different values from it for different systems, we'll need to add some ACPICA-ish code handling that specifically for Linux and we're a bit too late in the cycle for that.
So here's what I'm going to do. I'll revert commit b1ef29725865 for 4.1, but *only* for 4.1 (I've actually queued up a revert of it already) and I'll revert that revert during the 4.2 merge window.
Sounds like a good plan. Thanks!
In the meantime, we'll develop the code to implement the DMI-based quirks for the Dells and apply it for 4.2.
Are there any volunteers for doing the last part?
Will try to prepare patches for that tomorrow.
Best, Dominik
On Wednesday, May 13, 2015 08:36:47 AM Dominik Brodowski wrote:
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On Wed, May 13, 2015 at 01:38:59AM +0200, Rafael J. Wysocki wrote:
On Tuesday, May 12, 2015 10:43:33 AM Matthew Garrett wrote:
On Tue, May 12, 2015 at 10:29 AM, Mario Limonciello mario_limonciello@dell.com wrote:
Just to be clear, from the Dell side only the XPS 13 9343 has this _R=
EV
behavior.
=20 The Inspiron 7437 queries _REV and uses it to modify its EC behaviour, and apparently breaks on Linux without that. =20
What's wrong with a DMI quirk until I2S is mature on the kernel side =
and
userspace is new enough in distros? Is it too early in boot for DMI =
quirks?
That would enforce that no other machines can use _REV value of 5 to =
detect
Linux without breaking the 9343.
=20 DMI quirking is fine, but it has to be behind a config option. We're going to have to carry the quirk for several years because we have to support old userspace for an arbitrarily long time, and if there's no config option then Linux will be stuck in HDA mode for that entire time.
=20 One problem with the DMI-based approach is that _REV is constant in ACPIC=
A,
so to be able to return different values from it for different systems, w=
e'll
need to add some ACPICA-ish code handling that specifically for Linux and we're a bit too late in the cycle for that. =20 So here's what I'm going to do. I'll revert commit b1ef29725865 for 4.1, but *only* for 4.1 (I've actually queued up a revert of it already) and I'll revert that revert during the 4.2 merge window.
Sounds like a good plan. Thanks!
In the meantime, we'll develop the code to implement the DMI-based quirks for the Dells and apply it for 4.2. =20 Are there any volunteers for doing the last part?
Will try to prepare patches for that tomorrow.
Thanks a lot!
participants (2)
-
Dominik Brodowski -
Rafael J. Wysocki