[PATCH libdrm v2] xf86drm: Parse the separate files to retrieve the vendor, ... info

[Emil Velikov]

On 14 November 2016 at 09:56, Michel Dänzer <michel at daenzer.net> wrote:
> On 10/11/16 10:38 PM, Emil Velikov wrote:
>> On 10 November 2016 at 12:40, Nicolai Hähnle <nhaehnle at gmail.com> wrote:
>>> On 09.11.2016 19:08, Emil Velikov wrote:
>>>>
>>>> From: Emil Velikov <emil.velikov at collabora.com>
>>>>
>>>> Parsing config sysfs file wakes up the device. The latter of which may
>>>> be slow and isn't required to begin with.
>>>>
>>>> Reading through config is/was required since the revision is not
>>>> available by other means, although with a kernel patch in the way that
>>>> is about to change.
>>>>
>>>> Since returning 0 when one might expect a valid value is a no-go add a
>>>> workaround drmDeviceUseRevisionFile() which one can use to say "I don't
>>>> care if the revision file returns 0."
>>>>
>>>> v2: Complete rework - add new API to control the method, instead of
>>>> changing it underneat the users' feet.
>>>>
>>>> Cc: Michel Dänzer <michel.daenzer at amd.com>
>>>> Cc: Mauro Santos <registo.mailling at gmail.com>
>>>> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98502
>>>> Signed-off-by: Emil Velikov <emil.velikov at collabora.com>
>>>> ---
>>>> I don't have a strong preference for/against this or v1.
>>>>
>>>> With this Mesa will require a 2 line patch. With v1 things will get
>>>> fixed magically, when rebuilt against newer libdrm.
>>>>
>>>> Mauro I'll send the mesa patch in a second. Feel free to give it a spin.
>>>>
>>>> Thanks
>>>> ---
>>>>  xf86drm.c | 70
>>>> ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>>>>  xf86drm.h | 11 ++++++++++
>>>>  2 files changed, 78 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/xf86drm.c b/xf86drm.c
>>>> index 52add5e..676effc 100644
>>>> --- a/xf86drm.c
>>>> +++ b/xf86drm.c
>>>> @@ -113,6 +113,13 @@ void drmSetServerInfo(drmServerInfoPtr info)
>>>>      drm_server_info = info;
>>>>  }
>>>>
>>>> +static bool use_revision_file;
>>>> +
>>>> +void drmDeviceUseRevisionFile(void)
>>>> +{
>>>> +    use_revision_file = true;
>>>> +}
>>>
>>>
>>> I think this API of setting a magic hidden global variable is really nasty.
>>>
>>> Can we add new drmGetDevice[s] entry points with a flags parameter and a
>>> flag (per Michel's suggestion) which says "I don't care about the revision
>>> ID"? It kind of sucks because they'll have to get a silly name like
>>> drmGetDevice[s]2, but I think that's still better than magic global state.
>>>
>> AFACS Michel suggested (in his latest reply) to have
>> parse_separate_sysfs_files always and make the lack of revision file
>> fatal - falling back to ./config. Not a separate API [+ flags] ?
>
> You're mixing up two separate issues. Sorry if I was unclear before, let
> me try again:
>
> My first comment was about the "drmDeviceUseRevisionFile" name being
> misleading and not reflecting the intent. For this issue, I think
> Nicolai's suggestion is even better than just fixing the name.
>
> My other comment was that parse_separate_sysfs_files should be tried
> first even if the revision information is needed, and should only bail
> in that case if the separate revision sysfs files are missing, in which
> case parse_config_sysfs_file can be used as a fallback.
>
>
Makes perfect sense, tyvm !

>> P.S. /me is dreaming of the day when [wh]e'll get to drop 90% of
>> libdrm and it's hacks - viva la libdrm3 !
>
> Given the issues with bumping SONAME, I'm afraid you'll have to continue
> dreaming for a long time. :)
>
Sticking with libdrm3.so.X + libdrm3.pc should sort that, right ? That
plus a simple sed job to make the symbols different/unique.

Regardless, anything libdrm3 is unrelated to the topic in question.
Emil