[PATCH 01/19] drm: Wire up proper acquire ctx for plane functions

[Harry Wentland]

On 2017-03-28 03:02 AM, Daniel Vetter wrote:
> On Tue, Mar 28, 2017 at 08:23:53AM +0200, Daniel Vetter wrote:
>> On Mon, Mar 27, 2017 at 04:12:05PM -0400, Harry Wentland wrote:
>>> On Wednesday, March 22, 2017 10:50:40 PM EDT Daniel Vetter wrote:
>>>> This is just prep work to get an acquire ctx into every place where we
>>>> call ->update_plane or ->disable_plane.
>>>>
>>>> v2: Keep the hidden acquire_ctx pointers valid while transitioning.
>>>>
>>>> Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
>>>> ---
>>>>  drivers/gpu/drm/drm_plane.c | 52
>>>> ++++++++++++++++++++++++++++++++++++--------- 1 file changed, 42
>>>> insertions(+), 10 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/drm_plane.c b/drivers/gpu/drm/drm_plane.c
>>>> index a22e76837065..0d04888172a7 100644
>>>> --- a/drivers/gpu/drm/drm_plane.c
>>>> +++ b/drivers/gpu/drm/drm_plane.c
>>>> @@ -457,7 +457,8 @@ static int __setplane_internal(struct drm_plane *plane,
>>>>  			       uint32_t crtc_w, uint32_t crtc_h,
>>>>  			       /* src_{x,y,w,h} values are 16.16 fixed point */
>>>>  			       uint32_t src_x, uint32_t src_y,
>>>> -			       uint32_t src_w, uint32_t src_h)
>>>> +			       uint32_t src_w, uint32_t src_h,
>>>> +			       struct drm_modeset_acquire_ctx *ctx)
>>>>  {
>>>>  	int ret = 0;
>>>>
>>>> @@ -537,13 +538,26 @@ static int setplane_internal(struct drm_plane *plane,
>>>>  			     uint32_t src_x, uint32_t src_y,
>>>>  			     uint32_t src_w, uint32_t src_h)
>>>>  {
>>>> +	struct drm_modeset_acquire_ctx ctx;
>>>>  	int ret;
>>>>
>>>> -	drm_modeset_lock_all(plane->dev);
>>>> +	drm_modeset_acquire_init(&ctx, 0);
>>>> +retry:
>>>> +	ret = drm_modeset_lock_all_ctx(plane->dev, &ctx);
>>>> +	if (ret)
>>>> +		goto fail;
>>>> +	plane->dev->mode_config.acquire_ctx = &ctx;
>>>>  	ret = __setplane_internal(plane, crtc, fb,
>>>>  				  crtc_x, crtc_y, crtc_w, crtc_h,
>>>> -				  src_x, src_y, src_w, src_h);
>>>> -	drm_modeset_unlock_all(plane->dev);
>>>> +				  src_x, src_y, src_w, src_h, &ctx);
>>>> +
>>>> +fail:
>>>> +	if (ret == -EDEADLK) {
>>>> +		drm_modeset_backoff(&ctx);
>>>> +		goto retry;
>>>> +	}
>>>> +	drm_modeset_drop_locks(&ctx);
>>>> +	drm_modeset_acquire_fini(&ctx);
>>>>
>>>>  	return ret;
>>>>  }
>>>> @@ -613,11 +627,22 @@ static int drm_mode_cursor_universal(struct drm_crtc
>>>> *crtc, int32_t crtc_x, crtc_y;
>>>>  	uint32_t crtc_w = 0, crtc_h = 0;
>>>>  	uint32_t src_w = 0, src_h = 0;
>>>> +	struct drm_modeset_acquire_ctx ctx;
>>>>  	int ret = 0;
>>>>
>>>>  	BUG_ON(!crtc->cursor);
>>>>  	WARN_ON(crtc->cursor->crtc != crtc && crtc->cursor->crtc != NULL);
>>>>
>>>> +	drm_modeset_acquire_init(&ctx, 0);
>>>> +retry:
>>>> +	ret = drm_modeset_lock(&crtc->mutex, &ctx);
>>>> +	if (ret)
>>>> +		goto fail;
>>>> +	ret = drm_modeset_lock(&crtc->cursor->mutex, &ctx);
>>>> +	if (ret)
>>>> +		goto fail;
>>>> +	crtc->acquire_ctx = &ctx;
>>>> +
>>>>  	/*
>>>>  	 * Obtain fb we'll be using (either new or existing) and take an extra
>>>>  	 * reference to it if fb != null.  setplane will take care of dropping
>>>> @@ -662,7 +687,7 @@ static int drm_mode_cursor_universal(struct drm_crtc
>>>> *crtc, */
>>>>  	ret = __setplane_internal(crtc->cursor, crtc, fb,
>>>>  				crtc_x, crtc_y, crtc_w, crtc_h,
>>>> -				0, 0, src_w, src_h);
>>>> +				0, 0, src_w, src_h, &ctx);
>>>>
>>>>  	/* Update successful; save new cursor position, if necessary */
>>>>  	if (ret == 0 && req->flags & DRM_MODE_CURSOR_MOVE) {
>>>> @@ -670,6 +695,15 @@ static int drm_mode_cursor_universal(struct drm_crtc
>>>> *crtc, crtc->cursor_y = req->y;
>>>>  	}
>>>>
>>>> +fail:
>>>> +	if (ret == -EDEADLK) {
>>>> +		drm_modeset_backoff(&ctx);
>>>> +		goto retry;
>>>> +	}
>>>> +
>>>> +	drm_modeset_drop_locks(&ctx);
>>>> +	drm_modeset_acquire_fini(&ctx);
>>>> +
>>>>  	return ret;
>>>>  }
>>>>
>>>> @@ -696,12 +730,10 @@ static int drm_mode_cursor_common(struct drm_device
>>>> *dev, * If this crtc has a universal cursor plane, call that plane's update
>>>> * handler rather than using legacy cursor handlers.
>>>>  	 */
>>>> -	drm_modeset_lock_crtc(crtc, crtc->cursor);
>>>> -	if (crtc->cursor) {
>>>> -		ret = drm_mode_cursor_universal(crtc, req, file_priv);
>>>> -		goto out;
>>>> -	}
>>>> +	if (crtc->cursor)
>>>> +		return drm_mode_cursor_universal(crtc, req, file_priv);
>>>>
>>>> +	drm_modeset_lock_crtc(crtc, crtc->cursor);
>>>
>>> Why are you moving the lock? Shouldn't it still be covering the call to
>>> drm_mode_cursor_universal?
>>
>> It would deadlock, because the new acquire ctx dance for universal planes
>> also takes the same locks as this helper?
>>
>> But I just realized that crtc->cursor is NULL here, I can simplify this
>> some more.
>
> Specifically this gets reshuffled in patch 14, but that is blocked on the
> vmwgfx story for now.

Ah, right, the lock moves down into drm_mode_cursor_universal. I don't 
know how I missed that.

Reviewed-by: Harry Wentland <harry.wentland at amd.com>

Harry


> -Daniel
>