[PATCH xserver] randr: Do not check the screen size bound for gpu screens

[Nikhil Mahale]

Sorry for late reply, Hans. See inline -

On 06/13/2016 10:36 PM, Hans de Goede wrote:
> Hi,
>
> On 20-05-16 07:00, Nikhil Mahale wrote:
>> For gpu screen, CrtcSet set/adjust the master screen size along
>> mode in following callstack -
>>
>>   ProcRRSetCrtcConfig()
>>     |
>>     -> RRCrtcSet()
>>         |
>>         -> rrCheckPixmapBounding()
>>             |
>>             -> pScrPriv->rrScreenSetSize()
>>
>> Checking screen size bound for gpus screen cause some configurations
>> to fails, e.g
>>
>>   $ xrandr --output eDP --mode 1920x1080 --pos 0x0 --output HDMI \
>>   --mode 2560x1440 --pos 0x0
>>
>>   Here xrandr utility first sets screen size to 2560x1440 which
>>   gets resized to 1920x1080 on RRSetCrtcConfig request for eDP,
>>   and then RRSetCrtcConfig request for HDMI fails because
>>   of failure of screen bound check.
>
> Hmm, but one has the same problem when not using clone mode,
> then the master screen size must be made big enough to hold
> both crtc-s, so how come this has never been a problem then ?
>
> I've a feeling that in that case we end up doing things in
> finer grained steps. What if you do:
>
> $ xrandr --output eDP --mode 1920x1080 --pos 0x0
> $ xrandr --output HDMI --mode 2560x1440 --pos 0x0
>
> ? Does that work ?  If that works, which I would expect it will,
> then this should be fixed in the xrandr utility instead IMHO.
>
> Just circumventing the screen size check for slave outputs
> seem to go against the xrandr-1.2 spec to me.
>
> Also I guess one can reproduce the same problem without using
> slave-outputs, in which case your patch will not help.
>

I don't think we could reproduce this problem without using slave-
output, because rrScreenSetSize() path which I explained in commit
message is not there, isn't it?

Let me try to explain differece between both sequence of commands,
please correct me if required -

$ xrandr --output eDP --mode 1920x1080 --pos 0x0 --output HDMI \
--mode 2560x1440 --pos 0x0

-----------------------------------------------------------------------
| Cmd             | Screen size                  |  eDP      | HDMI   |
-----------------------------------------------------------------------
| RRSetScreenSize | 2560x1440                    |     -     |   -    |
-----------------------------------------------------------------------
| RRSetCrtcConfig | 1920x1080                    | 1920x1080 |   -    |
|                 | changed from 2560x1440       |           |        |
|                 | because of rrScreenSetSize() |           |        |
|                 | path explained in commit     |           |        |
|                 | msg. ....(A)                 |           |        |
-----------------------------------------------------------------------
| RRSetCrtcConfig | 1920x1080                    | 1920x1080 | failed |
-----------------------------------------------------------------------

$ xrandr --output eDP --mode 1920x1080 --pos 0x0
$ xrandr --output HDMI --mode 2560x1440 --pos 0x0


------------------------------------------------------------------------
| Cmd             | Screen size                |  eDP      | HDMI      |
------------------------------------------------------------------------
| RRSetScreenSize | 1920x1080                  |     -     |   -       |
------------------------------------------------------------------------
| RRSetCrtcConfig | 1920x1080                  | 1920x1080 |   -       |
------------------------------------------------------------------------
| RRSetScreenSize | 2560x1440                  | 1920x1080 |   -       |
------------------------------------------------------------------------
| RRSetCrtcConfig | 2560x1440                  | 1920x1080 | 2560x1440 |
------------------------------------------------------------------------

Case (A) is not there in second sequence of xrand commands, so you could 
not reproduce problem.

Thanks,
Nikhil Mahale

>
> Regards,
>
> Hans
>
>
>>
>> Signed-off-by: Nikhil Mahale <nmahale at nvidia.com>
>> ---
>>  randr/rrcrtc.c | 19 ++++++-------------
>>  1 file changed, 6 insertions(+), 13 deletions(-)
>>
>> diff --git a/randr/rrcrtc.c b/randr/rrcrtc.c
>> index 566a3db..82db9a8 100644
>> --- a/randr/rrcrtc.c
>> +++ b/randr/rrcrtc.c
>> @@ -1176,27 +1176,20 @@ ProcRRSetCrtcConfig(ClientPtr client)
>>
>>  #ifdef RANDR_12_INTERFACE
>>          /*
>> +         * For gpu screen, CrtcSet set/adjust the master screen size
>> along
>> +         * with mode.
>> +         *
>>           * Check screen size bounds if the DDX provides a 1.2 interface
>>           * for setting screen size. Else, assume the CrtcSet sets
>>           * the size along with the mode. If the driver supports
>> transforms,
>>           * then it must allow crtcs to display a subset of the
>> screen, so
>>           * only do this check for drivers without transform support.
>>           */
>> -        if (pScrPriv->rrScreenSetSize && !crtc->transforms) {
>> +        if (!pScreen->isGPU && pScrPriv->rrScreenSetSize &&
>> !crtc->transforms) {
>>              int source_width;
>>              int source_height;
>>              PictTransform transform;
>>              struct pixman_f_transform f_transform, f_inverse;
>> -            int width, height;
>> -
>> -            if (pScreen->isGPU) {
>> -                width = pScreen->current_master->width;
>> -                height = pScreen->current_master->height;
>> -            }
>> -            else {
>> -                width = pScreen->width;
>> -                height = pScreen->height;
>> -            }
>>
>>              RRTransformCompute(stuff->x, stuff->y,
>>                                 mode->mode.width, mode->mode.height,
>> @@ -1206,13 +1199,13 @@ ProcRRSetCrtcConfig(ClientPtr client)
>>
>>              RRModeGetScanoutSize(mode, &transform, &source_width,
>>                                   &source_height);
>> -            if (stuff->x + source_width > width) {
>> +            if (stuff->x + source_width > pScreen->width) {
>>                  client->errorValue = stuff->x;
>>                  free(outputs);
>>                  return BadValue;
>>              }
>>
>> -            if (stuff->y + source_height > height) {
>> +            if (stuff->y + source_height > pScreen->height) {
>>                  client->errorValue = stuff->y;
>>                  free(outputs);
>>                  return BadValue;
>>
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