Re: [Xen-devel] [PATCH v4 15/15] drm/xen: Explicitly disable automatic sending of vblank event

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

Hi

Am 27.01.20 um 10:53 schrieb Oleksandr Andrushchenko:
> Sorry for jumping in late
> 
> On 1/23/20 11:21 AM, Thomas Zimmermann wrote:
>> The atomic helpers automatically send out fake VBLANK events if no
>> vblanking has been initialized. This would apply to xen, but xen has
>> its own vblank logic. To avoid interfering with the atomic helpers,
>> disable automatic vblank events explictly.
>>
>> v4:
>>      * separate commit from core vblank changes
>>
>> Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
>> Acked-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
> Reviewed-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@xxxxxxxx>
> 
>> ---
>>   drivers/gpu/drm/xen/xen_drm_front_kms.c | 13 +++++++++++++
>>   1 file changed, 13 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/xen/xen_drm_front_kms.c 
>> b/drivers/gpu/drm/xen/xen_drm_front_kms.c
>> index 4f34c5208180..efde4561836f 100644
>> --- a/drivers/gpu/drm/xen/xen_drm_front_kms.c
>> +++ b/drivers/gpu/drm/xen/xen_drm_front_kms.c
>> @@ -220,6 +220,18 @@ static bool display_send_page_flip(struct 
>> drm_simple_display_pipe *pipe,
>>      return false;
>>   }
>>   
>> +static int display_check(struct drm_simple_display_pipe *pipe,
>> +                     struct drm_plane_state *plane_state,
>> +                     struct drm_crtc_state *crtc_state)
>> +{
>> +    /* Make sure that DRM helpers don't send VBLANK events
> Could you please put the comment on a separate line?

You mean to add an empty line between comment and code?

>> +     * automatically. Xen has it's own logic to do so.
>> +     */
>> +    crtc_state->no_vblank = false;
> And it is still confusing, e.g. comment says
> "Make sure that DRM helpers don't send VBLANK"
> and we set "no_vblank" flag to false...

I'll rephrase and add some more context.

Best regards
Thomas

>> +
>> +    return 0;
>> +}
>> +
>>   static void display_update(struct drm_simple_display_pipe *pipe,
>>                         struct drm_plane_state *old_plane_state)
>>   {
>> @@ -284,6 +296,7 @@ static const struct drm_simple_display_pipe_funcs 
>> display_funcs = {
>>      .enable = display_enable,
>>      .disable = display_disable,
>>      .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
>> +    .check = display_check,
>>      .update = display_update,
>>   };
>>   

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer

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