On 12/17/18 12:17 PM, Stephan Gerhold wrote:
On Mon, Dec 17, 2018 at 08:52:46AM -0600, Pierre-Louis Bossart wrote:
On 12/16/18 12:54 PM, Stephan Gerhold wrote:
Hi,
I have an Intel Bay Trail (BYT-T) tablet that was originally shipped
with Android. With the right quirks, bytcr-rt5640 is working fine, but
there is a problem in sst_acpi.c that is preventing it from working
with a mainline kernel:
Even though this is a BYT-T device, there is no IRQ at index 5 in the
ACPI DSDT table. This means that SST will fail to probe, and actually
leads to a NULL pointer dereference later when the ALSA device is first
opened. (I have submitted a possible solution for this as
"[PATCH] ASoC: Intel: sst: Delay machine device creation until after
initialization")
The correct IRQ is actually located on index 0, just like it is already
being used for BYT-CR devices. So if I force is_byt_cr() to return TRUE,
everything works as expected.
So the root cause of your problem is that the detection of byt-cr doesn't
work? That would be a first.
No. is_byt_cr() works correctly, as my device is a BYT-T (not a BYT-CR)
device. :)
What information is your analysis based on and how do you infer this
conclusion? The BYT-T and BYT-CR silicon dies are identical, product
documentation can barely be trusted and it's a package difference that
can only be tested indirectly.
I don't mean to dismiss your claim, just want to find out if this is a
case where the PMIC-type-based byt_cr detection fails or if we have a
BIOS issue. Another smoking gun is if you find in your code traces of
SSP0 being used.
The problem here is that the kernel expects the IRQ at index 5 for BYT-T
devices, but my device has only a single IRQ listed. Forcing is_byt_cr()
to return TRUE is just a workaround to make it use the IRQ at index 0
(which is the correct one).
Currently, sst_acpi supports these two variations:
- BYT-T: 5 IRQs listed -> acpi_ipc_irq_index = 5
- BYT-CR: 5 IRQs listed -> acpi_ipc_irq_index = 0
On my device (and a few other Android based BYT-T devices) I have found:
- BYT-T: 1 IRQ listed -> acpi_ipc_irq_index = 0
but at the moment the kernel attempts to use acpi_ipc_irq_index = 5 from
BYT-T above.
Can you please double-check that CONFIG_IOSF_MBI is enabled and provide a
trace of the bios status in this piece of code:
/* bits 26:27 mirror PMIC options */
bios_status = (bios_status >> 26) & 3;
if ((bios_status == 1) || (bios_status == 3))
*bytcr = true;
else
dev_info(dev, "BYT-CR not detected\n");
Here is the relevant part from the ACPI DSDT table:
Name (_ADR, Zero) // _ADR: Address
Name (_HID, "80860F28" /* Intel SST Audio DSP */) // _HID: Hardware ID
Name (_CID, "80860F28" /* Intel SST Audio DSP */) // _CID: Compatible ID
Name (_DDN, "Intel(R) Low Power Audio Controller - 80860F28") // _DDN: DOS Device Name
Name (_SUB, "80867270") // _SUB: Subsystem ID
Name (_UID, One) // _UID: Unique ID
Name (RBUF, ResourceTemplate ()
{
Memory32Fixed (ReadWrite,
0x12345678, // Address Base
0x00200000, // Address Length
_Y08)
Memory32Fixed (ReadWrite,
0xFE830000, // Address Base
0x00001000, // Address Length
_Y09)
Memory32Fixed (ReadWrite,
0x55AA55AA, // Address Base
0x00200000, // Address Length
_Y0A)
Interrupt (ResourceConsumer, Level, ActiveLow, Exclusive, ,, )
{
0x0000001D,
}
})
Unlike many of the other DSDT dumps I've looked at, there is only one
interrupt listed. Full ACPI DSDT table is at [1].
Since there is no IRQ at index 5, platform_get_irq will return -ENXIO.
Couldn't we fall back to index 0 in this case? I would say that if the
seemingly "correct" IRQ at index 5 does not even exist, we still have
a better chance of picking the right one if we try the one at index 0.
Or we could check the number of interrupts that are actually available.
The other option would be some kind of DMI-based quirk, but personally
I would prefer to avoid that.. (In my opinion, there is way too much
device specific code with the quirks etc already...)
Or do you have any other suggestions?
Thanks,
Stephan
[1]: https://github.com/me176c-dev/me176c-acpi/blob/f48c78c11b0819b899f988407b6ece3d8c2cca71/dsdt.dsl#L3989-L4035
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