On 10/23/23 14:23, Hans de Goede wrote:
Hi,
On 10/23/23 20:45, Pierre-Louis Bossart wrote:
On 10/21/23 16:15, Hans de Goede wrote:
The Lenovo Yoga Tab 3 Pro YT3-X90 x86 tablet, which ships with Android with a custom kernel as factory OS, does not list the used WM5102 codec inside its DSDT.
Workaround this with a new snd_soc_acpi_intel_baytrail_machines[] entry which matches on the SST id instead of the codec id like nocodec does, combined with using a machine_quirk callback which returns NULL on other machines to skip the new entry on other machines.
The work-around sounds fine, but out of curiosity what causes the codec driver to probe if there's no ACPI HID?
Really wondering how we avoid the -517 error code with the deferred probe never completing because the codec driver never probed and registered the needed components?
These x86 android tablets ship with pretty broken DSDTs with A whole bunch of (usually i2c) devices missing like e.g. the touchscreen and the accelerometer.
For the factory Android install this is not an issue because it uses drivers which instantiate the i2c-clients itself using hardcoded i2c-bus, i2c-address and irqs.
To make this work under Linux I've written a special helper "driver" which loads only on these broken DSDT devices based on DMI modalias and then identifies the exact model (also by DMI) and instantiates the correct devices from this "driver" (really more of an old fashioned board file). This code also adds all the necessary properties, etc. to make standard drivers work, so all model specific knowledge missing from the DSDT is encoded in this special x86-android-tablets driver.
I've also submitted a patch for that driver to instantiate the codec SPI device using spi_device_id matching instead of acpi_device_id matching:
https://lore.kernel.org/platform-driver-x86/20231014205314.59333-5-hdegoede@...
So this is the other side of the puzzle, I hope this helps explain how I actually got this working.
Ah yes, thanks Hans for the information. The amount of work-arounds for a broken DSDT and enumeration is just mind-boggling.... Oh well.
For the series
Acked-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com