[RFC v3 5/8] drm/msm: update cursors asynchronously through atomic

Archit Taneja architt at codeaurora.org
Wed May 17 05:26:25 UTC 2017


Hi,

On 05/16/2017 08:14 PM, Archit Taneja wrote:
>
>
> On 5/13/2017 12:40 AM, Gustavo Padovan wrote:
>> From: Gustavo Padovan <gustavo.padovan at collabora.com>
>>
>> Add support to async updates of cursors by using the new atomic
>> interface for that. Basically what this commit does is do what
>> mdp5_update_cursor_plane_legacy() did but through atomic.
>
> Works well on DB820c (which has a APQ8096 SoC).
>
> Tested-by: Archit Taneja <architt at codeaurora.org>

Actually, after some more thorough testing, I found one issue, mentioned below.

>
>>
>> v3: move size checks back to drivers (Ville Syrjälä)
>>
>> v2: move fb setting to core and use new state (Eric Anholt)
>>
>> Cc: Rob Clark <robdclark at gmail.com>
>> Signed-off-by: Gustavo Padovan <gustavo.padovan at collabora.com>
>> ---
>>   drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c | 151 +++++++++++++-----------------
>>   1 file changed, 63 insertions(+), 88 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c
>> index a38c5fe..07106c1 100644
>> --- a/drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c
>> +++ b/drivers/gpu/drm/msm/mdp/mdp5/mdp5_plane.c
>> @@ -33,15 +33,6 @@ static int mdp5_plane_mode_set(struct drm_plane *plane,
>>           struct drm_crtc *crtc, struct drm_framebuffer *fb,
>>           struct drm_rect *src, struct drm_rect *dest);
>>   -static int mdp5_update_cursor_plane_legacy(struct drm_plane *plane,
>> -        struct drm_crtc *crtc,
>> -        struct drm_framebuffer *fb,
>> -        int crtc_x, int crtc_y,
>> -        unsigned int crtc_w, unsigned int crtc_h,
>> -        uint32_t src_x, uint32_t src_y,
>> -        uint32_t src_w, uint32_t src_h,
>> -        struct drm_modeset_acquire_ctx *ctx);
>> -
>>   static struct mdp5_kms *get_kms(struct drm_plane *plane)
>>   {
>>       struct msm_drm_private *priv = plane->dev->dev_private;
>> @@ -257,7 +248,7 @@ static const struct drm_plane_funcs mdp5_plane_funcs = {
>>   };
>>     static const struct drm_plane_funcs mdp5_cursor_plane_funcs = {
>> -        .update_plane = mdp5_update_cursor_plane_legacy,
>> +        .update_plane = drm_atomic_helper_update_plane,
>>           .disable_plane = drm_atomic_helper_disable_plane,
>>           .destroy = mdp5_plane_destroy,
>>           .set_property = drm_atomic_helper_plane_set_property,
>> @@ -484,11 +475,73 @@ static void mdp5_plane_atomic_update(struct drm_plane *plane,
>>       }
>>   }
>>   +static int mdp5_plane_atomic_async_check(struct drm_plane *plane,
>> +                     struct drm_plane_state *state)
>> +{
>> +    struct mdp5_plane_state *mdp5_state = to_mdp5_plane_state(state);
>> +    struct drm_crtc_state *crtc_state;
>> +
>> +    crtc_state = drm_atomic_get_existing_crtc_state(state->state,
>> +                            state->crtc);

I see a kernel splat here (a NULL pointer dereference). The async_check
function assumes that there is always going to be a plane_state->crtc
available. This doesn't seem to be the case at least in the
drm_atomic_helper_disable_plane() path. Moving the check to set
legacy_cursor_update after calling __drm_atomic_helper_disable_plane()
seems to fix the issue. Do you think it's a legit fix?

One more point w.r.t msm driver is that we don't use the default
drm_atomic_helper_commit() for our atomic_commit op. So I had to
call drm_atomic_helper_async_commit() from our atomic_commit
implementation
(i.e, in msm_atomic_commit in drivers/gpu/drm/msm/msm_atomic.c)

Thanks,
Archit

>> +    if (WARN_ON(!crtc_state))
>> +        return -EINVAL;
>> +
>> +    if (!crtc_state->active)
>> +        return -EINVAL;
>> +
>> +    mdp5_state = to_mdp5_plane_state(state);
>> +
>> +    /* don't use fast path if we don't have a hwpipe allocated yet */
>> +    if (!mdp5_state->hwpipe)
>> +        return -EINVAL;
>> +
>> +    /* only allow changing of position(crtc x/y or src x/y) in fast path */
>> +    if (plane->state->crtc != state->crtc ||
>> +        plane->state->src_w != state->src_w ||
>> +        plane->state->src_h != state->src_h ||
>> +        plane->state->crtc_w != state->crtc_w ||
>> +        plane->state->crtc_h != state->crtc_h ||
>> +        !plane->state->fb ||
>> +        plane->state->fb != state->fb)
>> +        return -EINVAL;
>> +
>> +    return 0;
>> +}
>> +
>> +static void mdp5_plane_atomic_async_update(struct drm_plane *plane,
>> +                       struct drm_plane_state *new_state)
>> +{
>> +    plane->state->src_x = new_state->src_x;
>> +    plane->state->src_y = new_state->src_y;
>> +    plane->state->crtc_x = new_state->crtc_x;
>> +    plane->state->crtc_y = new_state->crtc_y;
>> +
>> +    if (plane_enabled(new_state)) {
>> +        struct mdp5_ctl *ctl;
>> +        struct mdp5_pipeline *pipeline =
>> +                    mdp5_crtc_get_pipeline(plane->crtc);
>> +        int ret;
>> +
>> +        ret = mdp5_plane_mode_set(plane, new_state->crtc, new_state->fb,
>> +                &new_state->src, &new_state->dst);
>> +        WARN_ON(ret < 0);
>> +
>> +        ctl = mdp5_crtc_get_ctl(new_state->crtc);
>> +
>> +        mdp5_ctl_commit(ctl, pipeline, mdp5_plane_get_flush(plane));
>> +    }
>> +
>> +    *to_mdp5_plane_state(plane->state) =
>> +        *to_mdp5_plane_state(new_state);
>> +}
>> +
>>   static const struct drm_plane_helper_funcs mdp5_plane_helper_funcs = {
>>           .prepare_fb = mdp5_plane_prepare_fb,
>>           .cleanup_fb = mdp5_plane_cleanup_fb,
>>           .atomic_check = mdp5_plane_atomic_check,
>>           .atomic_update = mdp5_plane_atomic_update,
>> +        .atomic_async_check = mdp5_plane_atomic_async_check,
>> +        .atomic_async_update = mdp5_plane_atomic_async_update,
>>   };
>>     static void set_scanout_locked(struct mdp5_kms *mdp5_kms,
>> @@ -997,84 +1050,6 @@ static int mdp5_plane_mode_set(struct drm_plane *plane,
>>       return ret;
>>   }
>>   -static int mdp5_update_cursor_plane_legacy(struct drm_plane *plane,
>> -            struct drm_crtc *crtc, struct drm_framebuffer *fb,
>> -            int crtc_x, int crtc_y,
>> -            unsigned int crtc_w, unsigned int crtc_h,
>> -            uint32_t src_x, uint32_t src_y,
>> -            uint32_t src_w, uint32_t src_h,
>> -            struct drm_modeset_acquire_ctx *ctx)
>> -{
>> -    struct drm_plane_state *plane_state, *new_plane_state;
>> -    struct mdp5_plane_state *mdp5_pstate;
>> -    struct drm_crtc_state *crtc_state = crtc->state;
>> -    int ret;
>> -
>> -    if (!crtc_state->active || drm_atomic_crtc_needs_modeset(crtc_state))
>> -        goto slow;
>> -
>> -    plane_state = plane->state;
>> -    mdp5_pstate = to_mdp5_plane_state(plane_state);
>> -
>> -    /* don't use fast path if we don't have a hwpipe allocated yet */
>> -    if (!mdp5_pstate->hwpipe)
>> -        goto slow;
>> -
>> -    /* only allow changing of position(crtc x/y or src x/y) in fast path */
>> -    if (plane_state->crtc != crtc ||
>> -        plane_state->src_w != src_w ||
>> -        plane_state->src_h != src_h ||
>> -        plane_state->crtc_w != crtc_w ||
>> -        plane_state->crtc_h != crtc_h ||
>> -        !plane_state->fb ||
>> -        plane_state->fb != fb)
>> -        goto slow;
>> -
>> -    new_plane_state = mdp5_plane_duplicate_state(plane);
>> -    if (!new_plane_state)
>> -        return -ENOMEM;
>> -
>> -    new_plane_state->src_x = src_x;
>> -    new_plane_state->src_y = src_y;
>> -    new_plane_state->src_w = src_w;
>> -    new_plane_state->src_h = src_h;
>> -    new_plane_state->crtc_x = crtc_x;
>> -    new_plane_state->crtc_y = crtc_y;
>> -    new_plane_state->crtc_w = crtc_w;
>> -    new_plane_state->crtc_h = crtc_h;
>> -
>> -    ret = mdp5_plane_atomic_check_with_state(crtc_state, new_plane_state);
>> -    if (ret)
>> -        goto slow_free;
>> -
>> -    if (new_plane_state->visible) {
>> -        struct mdp5_ctl *ctl;
>> -        struct mdp5_pipeline *pipeline = mdp5_crtc_get_pipeline(crtc);
>> -
>> -        ret = mdp5_plane_mode_set(plane, crtc, fb,
>> -                      &new_plane_state->src,
>> -                      &new_plane_state->dst);
>> -        WARN_ON(ret < 0);
>> -
>> -        ctl = mdp5_crtc_get_ctl(crtc);
>> -
>> -        mdp5_ctl_commit(ctl, pipeline, mdp5_plane_get_flush(plane));
>> -    }
>> -
>> -    *to_mdp5_plane_state(plane_state) =
>> -        *to_mdp5_plane_state(new_plane_state);
>> -
>> -    mdp5_plane_destroy_state(plane, new_plane_state);
>> -
>> -    return 0;
>> -slow_free:
>> -    mdp5_plane_destroy_state(plane, new_plane_state);
>> -slow:
>> -    return drm_atomic_helper_update_plane(plane, crtc, fb,
>> -                          crtc_x, crtc_y, crtc_w, crtc_h,
>> -                          src_x, src_y, src_w, src_h, ctx);
>> -}
>> -
>>   /*
>>    * Use this func and the one below only after the atomic state has been
>>    * successfully swapped
>>
>

diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
index 19e5a4f5529a..b384c985cd08 100644
--- a/drivers/gpu/drm/drm_atomic_helper.c
+++ b/drivers/gpu/drm/drm_atomic_helper.c
@@ -2230,13 +2230,14 @@ int drm_atomic_helper_disable_plane(struct drm_plane *plane,
  		goto fail;
  	}

-	if (plane_state->crtc && (plane == plane->crtc->cursor))
-		plane_state->state->legacy_cursor_update = true;
-
  	ret = __drm_atomic_helper_disable_plane(plane, plane_state);
  	if (ret != 0)
  		goto fail;

+	if (plane_state->crtc && (plane == plane->crtc->cursor))
+		plane_state->state->legacy_cursor_update = true;
+
+
  	ret = drm_atomic_commit(state);
  fail:
  	drm_atomic_state_put(state);


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