[PATCH 1/3] Skip xf86HandleColormaps() at color depth 30.

[Michel Dänzer]

On 2017-12-27 09:49 PM, Mario Kleiner wrote:
> On 12/27/2017 12:56 PM, Michel Dänzer wrote:
>> On 2017-12-23 07:07 AM, Mario Kleiner wrote:
>>> The hardware gamma luts get bypassed at color
>>> depth 30 anyway, so skip their setup.
>>>
>>> Also skip drmmode_crtc_gamma_set() for a screen
>>> with depth 30.
>>>
>>> Signed-off-by: Mario Kleiner <mario.kleiner.de at gmail.com>
>>> ---
>>>   src/drmmode_display.c | 10 ++++++++--
>>>   1 file changed, 8 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/src/drmmode_display.c b/src/drmmode_display.c
>>> index 7ad3235..e5f9dbe 100644
>>> --- a/src/drmmode_display.c
>>> +++ b/src/drmmode_display.c
>>> @@ -1275,6 +1275,10 @@ drmmode_crtc_gamma_set(xf86CrtcPtr crtc,
>>> uint16_t *red, uint16_t *green,
>>>       RADEONInfoPtr info = RADEONPTR(scrn);
>>>       int i;
>>>   +    /* Hw gamma lut's are bypassed at color depth 30 */
>>> +    if (scrn->depth == 30)
>>> +        return;
>>
>> It's better to set xf86CrtcFuncsRec::gamma_set = NULL in this case, to
>> prevent the X server from wasting work calculating gamma tables that
>> will never be used.
> 
> I looked at that, but as far as i understand, wouldn't NULL'ing that
> entry affect all active X-Screens, not only the depth 30 ones, as each
> screen only references the same shared static struct with function
> pointers in the driver?

That's right.

> At least for the use cases of many of "my" users, two separate
> x-screens, with ZaphodHeads and different color depth wouldn't be an
> unexpected setup.

Then we'll need to use a different xf86CrtcFuncsRec instance per screen
instead of a single one for all screens.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer