[PATCH] drm/sti: forbid plane on several mixer

[Vincent ABRIOU]

On 09/15/2016 05:57 PM, Ville Syrjälä wrote:
> On Thu, Sep 15, 2016 at 04:59:55PM +0200, Vincent ABRIOU wrote:
>>
>>
>> On 09/15/2016 04:27 PM, Ville Syrjälä wrote:
>>> On Wed, Sep 14, 2016 at 01:40:02PM +0200, Vincent Abriou wrote:
>>>> When a plane is going to be enabled we re-evaluate the possible crtcs
>>>> for the associated drm plane. Only the crtc on which the plane should be
>>>> displayed is considered possible until the plane is disabled.
>>>> Indeed STI hardware does not allow to dynamically change
>>>> the plane's crtc/mixer assignment when the plane is in use (gdp is
>>>> running).
>>>>
>>>> Signed-off-by: Vincent Abriou <vincent.abriou at st.com>
>>>> ---
>>>>  drivers/gpu/drm/sti/sti_gdp.c   | 15 +++++++++++++++
>>>>  drivers/gpu/drm/sti/sti_plane.h |  2 ++
>>>>  2 files changed, 17 insertions(+)
>>>>
>>>> diff --git a/drivers/gpu/drm/sti/sti_gdp.c b/drivers/gpu/drm/sti/sti_gdp.c
>>>> index 3fc62c1..f7cd671 100644
>>>> --- a/drivers/gpu/drm/sti/sti_gdp.c
>>>> +++ b/drivers/gpu/drm/sti/sti_gdp.c
>>>> @@ -71,6 +71,9 @@ static struct gdp_format_to_str {
>>>>  #define GDP_NODE_NB_BANK        2
>>>>  #define GDP_NODE_PER_FIELD      2
>>>>
>>>> +#define MAIN_CRTC_MASK          BIT(0)
>>>> +#define AUX_CRTC_MASK           BIT(1)
>>>> +
>>>>  struct sti_gdp_node {
>>>>  	u32 gam_gdp_ctl;
>>>>  	u32 gam_gdp_agc;
>>>> @@ -690,6 +693,12 @@ static int sti_gdp_atomic_check(struct drm_plane *drm_plane,
>>>>  		}
>>>>  	}
>>>>
>>>> +	/* re-evaluate the possible crtcs */
>>>> +	if (mixer->id == STI_MIXER_MAIN)
>>>> +		drm_plane->possible_crtcs = MAIN_CRTC_MASK;
>>>> +	else
>>>> +		drm_plane->possible_crtcs = AUX_CRTC_MASK;
>>>
>>> This stuff isn't meant to be changed dynamically. There's no event for
>>> telling userspace to re-examine this sort of information.
>>
>> Yes sure. But by doing this, I let the userspace the ability to fix plan
>> assignment by it self by re-evaluating the possible CRTC. Before new
>> plane assignment.
>
> Only if it would re-fetch all planes/crtcs/etc. resources between every
> operation. Doing that would suck big time. And with atomic that's not
> even a theoretical option since everything would be configured with a
> single ioctl.
>

I test with weston-1.11.0 and the behavior changed.
It is now forbidden to set a plane on 2 differents CRTC.
I will not going further on this patch.

BR
Vincent

>> The kernel driver is then flexible enough to avoid Kernel crash.
>
> If the kernel crashes due to an an unsupported plane configuration,
> then the kernel has to be fixed.
>
>>
>> BR
>> Vincent
>>
>>>
>>>> +
>>>>  	DRM_DEBUG_KMS("CRTC:%d (%s) drm plane:%d (%s)\n",
>>>>  		      crtc->base.id, sti_mixer_to_str(mixer),
>>>>  		      drm_plane->base.id, sti_plane_to_str(plane));
>>>> @@ -846,6 +855,9 @@ static void sti_gdp_atomic_disable(struct drm_plane *drm_plane,
>>>>  {
>>>>  	struct sti_plane *plane = to_sti_plane(drm_plane);
>>>>
>>>> +	/* restore possible crtcs value with the initial value */
>>>> +	drm_plane->possible_crtcs = plane->init_possible_crtcs;
>>>> +
>>>>  	if (!drm_plane->crtc) {
>>>>  		DRM_DEBUG_DRIVER("drm plane:%d not enabled\n",
>>>>  				 drm_plane->base.id);
>>>> @@ -917,6 +929,9 @@ struct drm_plane *sti_gdp_create(struct drm_device *drm_dev,
>>>>
>>>>  	sti_gdp_init(gdp);
>>>>
>>>> +	/* store the initial value of possible crtcs */
>>>> +	gdp->plane.init_possible_crtcs = possible_crtcs;
>>>> +
>>>>  	res = drm_universal_plane_init(drm_dev, &gdp->plane.drm_plane,
>>>>  				       possible_crtcs,
>>>>  				       &sti_gdp_plane_helpers_funcs,
>>>> diff --git a/drivers/gpu/drm/sti/sti_plane.h b/drivers/gpu/drm/sti/sti_plane.h
>>>> index ce3e8d6..70c5312 100644
>>>> --- a/drivers/gpu/drm/sti/sti_plane.h
>>>> +++ b/drivers/gpu/drm/sti/sti_plane.h
>>>> @@ -66,12 +66,14 @@ struct sti_fps_info {
>>>>   * @plane:              drm plane it is bound to (if any)
>>>>   * @desc:               plane type & id
>>>>   * @status:             to know the status of the plane
>>>> + * @init_possile_crtcs: store the initial possible crtc value
>>>>   * @fps_info:           frame per second info
>>>>   */
>>>>  struct sti_plane {
>>>>  	struct drm_plane drm_plane;
>>>>  	enum sti_plane_desc desc;
>>>>  	enum sti_plane_status status;
>>>> +	u32 init_possible_crtcs;
>>>>  	struct sti_fps_info fps_info;
>>>>  };
>>>>
>>>> --
>>>> 1.9.1
>>>>
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>>>
>