Re: [PATCH] serdev: Add ACPI devices by ResourceSource field

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Hi,

On 23-09-2019 00:29, Maximilian Luz wrote:
Hi all,

On 9/20/19 5:00 PM, Hans de Goede wrote:
So as promised I've given this patch a try, unfortunately it breaks
existing users of ACPI serdev device instantation.

After adding this patch "ls /sys/bus/serial/devices" is empty,
where as before it gives:

[root@dhcp-45-50 ~]# ls -l /sys/bus/serial/devices/
total 0
lrwxrwxrwx. 1 root root 0 Sep 20 16:43 serial0 -> ../../../devices/pci0000:00/8086228A:00/serial0
lrwxrwxrwx. 1 root root 0 Sep 20 16:43 serial0-0 -> ../../../devices/pci0000:00/8086228A:00/serial0/serial0-0

And since the serdev is missing bluetooth does not work.

Thanks to some testing by Hans, it turns out that the reason for this is
that acpi_walk_resources fails with AE_AML_INVALID_RESOURCE_TYPE for a
specific device. If anyone is interested, the _CRS of the device in
question is

     Method (_CRS, 0, NotSerialized)  // _CRS: Current Resource Settings
     {
         Name (NAM, Buffer (0x14)
         {
             "\\_SB.PCI0.SDHB.BRC1"
         })
         Name (SPB, Buffer (0x0C)
         {
             /* 0000 */  0x8E, 0x1D, 0x00, 0x01, 0x00, 0xC0, 0x02, 0x00,
             /* 0008 */  0x00, 0x01, 0x00, 0x00
         })
         Name (END, ResourceTemplate ()
         {
         })
         Concatenate (SPB, NAM, Local0)
         Concatenate (Local0, END, Local1)
         Return (Local1)
     }

To solve this, I propose ignoring errors that occur when evaluating the
_CRS method. Note that with the previously discussed change for v2,
where we will only look at the first device in _CRS, we should be able
to handle errors from the actual serdev device allocation separately
(and only ignore AML evaluation errors).

Further, I think it might also make sense to move the status and
already-enumerated checks out of acpi_serdev_register_device to before
looking at _CRS.

Ack, this is what drivers/i2c/i2c-core-acpi.c is doing and more in general
all ACPI enumeration code always first checks _STA before doing anything
else, so I think it would be best to do this here too.

Actually I think it might be best to fully copy how drivers/i2c/i2c-core-acpi.c
does things.

Regards,

Hans





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