[Mesa-dev] [PATCH 3/5] egl/android: remove droid_probe_driver()

[Emil Velikov]

On 13 August 2018 at 16:43, Tomasz Figa <tfiga at chromium.org> wrote:
> On Tue, Aug 14, 2018 at 12:35 AM Emil Velikov <emil.l.velikov at gmail.com> wrote:
>>
>> On 13 August 2018 at 16:16, Tomasz Figa <tfiga at chromium.org> wrote:
>> > Hi Emil,
>> >
>> > On Mon, Aug 13, 2018 at 11:48 PM Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> >>
>> >> From: Emil Velikov <emil.velikov at collabora.com>
>> >>
>> >> The function name is misleading - it effectively checks if
>> >> loader_get_driver_for_fd fails. Which can happen only only on strdup
>> >> error - a close to impossible scenario.
>> >
>> > How about a DRI node which doesn't have a driver in Mesa?
>> >
>> Can you elaborate a bit - are you thinking of any of the following or
>> something else:
>>  - no support for vendor X
>>  - supported vendor, missing vendor/device pci id for device X
>>  - supported vendor, built w/o it
>>
>> All these are fairly different cases, with somewhat different solution
>> for each one.
>
> Let's say "no support for vendor X", but supported vendor Y GPU next
> to it. We want this code to skip vendor X DRI node and choose vendor Y
> DRI node.
>
>>
>> Fwiw the function loader_get_driver_for_fd does:
>>  - gets the vendor/device pci id and maps that to a driver_name
>>  - if device not a pci device (or query fails) - fallback to the name
>> as returned in drmGetVersion
>
> Good catch. Looks like I misunderstood what it does when reviewing
> Rob's series and existing code doesn't work as I expected. I think it
> would just error out in the case above, right?
>
Determining if a device is "supported" is fairly subtle:
For example, even if you open the foo_dri.so the driver can fail due
to old kernel module, LLVM version, etc.
One solution is to continue loading up-to dri2_create_screen() - if it
fails fall-back to the next device.

Any objections if I do that as follow-up patch, if you agree of course?

Feels a bit dirty, but will work until we get something like
EGL_EXT_explicit_device and EGL_MESA_query_renderer.

Thanks
Emil