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 <[email protected]>
---
 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 <[email protected]>

Harry


-Daniel

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