On Wed, Jul 14, 2021 at 08:18:55PM +0100, Mark Brown wrote: > On Wed, Jul 14, 2021 at 08:41:27PM +0300, Laurent Pinchart wrote: > > On Wed, Jul 14, 2021 at 06:28:46PM +0100, Mark Brown wrote: > > > On Wed, Jul 14, 2021 at 08:18:13PM +0300, Laurent Pinchart wrote: > > > > It's only one data point, but we're seeing adoption of the ACPI > > > > DT-in-DSD for camera. It's still not pretty of course. > > > > > > By non-Linux system vendors? > > > > For Windows-based machines, yes. It's fairly new, and the information I > > have is that those machines may ship DSDT containing both Windows-style > > (read: crap) data and Linux-style data for the same nodes. My fear is > > that only the former will be properly tested and the latter will thus be > > incorrect. The future will tell (I'm as usual very hopeful). > > Adding the Intel audio people - it'd be good if we could get some > similar stuff started for the audio things. Sadly in these sorts of > cases AIUI the Windows thing is broadly to match DMI data and supply > platform data so it's more a case of just not having essential > information in firmware, a bad format would be better TBH (assuming it's > accurate which also requires loads of quirks...). On the camera side, the Windows-based machines I've worked with (Skylake and Kabylak) have data in the DSDT. There's data we can use directly, and there's a lot that is hardcoded in the Windows driver (including what voltage to program on the different outputs of an I2C-controlled regulator - you get that wrong, you fry your camera). I believe Intel provides a small set of reference designs with several options to the OEMs, and I wouldn't be surprised if some of the data present in ACPI that we don't know how to interpret would identify these options. I don't think the Windows driver has DMI-based quirks, the driver isn't machine-specific as far as I can tell. For newer devices, ACPI should contain Windows data in a format that the Windows team decides on its own, and data that is actually usable in the _DSD for Linux. I've also heard that the power management would be saner, with PM actually implemented in the DSDT. I haven't seen those DSDT yet though. -- Regards, Laurent Pinchart
