[PATCH 8/8] drm/ssd130x: Preallocate xfrm buffer in plane's atomic_check

[Thomas Zimmermann]

Preallocate the xfrm buffer's storage in the plane's atomic_check
function if a format conversion will be necessary. Allows the update
to fail if no memory is available. Avoids the same allocation within
atomic_update, which may not fail.

Also inline drm_plane_helper_atomic_check() into the driver and thus
return early for invisible planes. Avoids memory allocation entirely
in this case.

Signed-off-by: Thomas Zimmermann <tzimmerm...@suse.de>
---
 drivers/gpu/drm/solomon/ssd130x.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x.c 
b/drivers/gpu/drm/solomon/ssd130x.c
index 508588bd2d565..3788d847e50ff 100644
--- a/drivers/gpu/drm/solomon/ssd130x.c
+++ b/drivers/gpu/drm/solomon/ssd130x.c
@@ -601,17 +601,27 @@ static int 
ssd130x_primary_plane_helper_atomic_check(struct drm_plane *plane,
 {
        struct drm_device *drm = plane->dev;
        struct ssd130x_device *ssd130x = drm_to_ssd130x(drm);
-       struct drm_plane_state *plane_state = 
drm_atomic_get_new_plane_state(state, plane);
-       struct ssd130x_plane_state *ssd130x_state = 
to_ssd130x_plane_state(plane_state);
+       struct drm_plane_state *new_plane_state = 
drm_atomic_get_new_plane_state(state, plane);
+       struct ssd130x_plane_state *ssd130x_state = 
to_ssd130x_plane_state(new_plane_state);
+       struct drm_crtc *new_crtc = new_plane_state->crtc;
+       struct drm_crtc_state *new_crtc_state = NULL;
        unsigned int page_height = ssd130x->device_info->page_height;
        unsigned int pages = DIV_ROUND_UP(ssd130x->height, page_height);
        const struct drm_format_info *fi;
        unsigned int pitch;
        int ret;
 
-       ret = drm_plane_helper_atomic_check(plane, state);
+       if (new_crtc)
+               new_crtc_state = drm_atomic_get_new_crtc_state(state, new_crtc);
+
+       ret = drm_atomic_helper_check_plane_state(new_plane_state, 
new_crtc_state,
+                                                 DRM_PLANE_NO_SCALING,
+                                                 DRM_PLANE_NO_SCALING,
+                                                 false, false);
        if (ret)
                return ret;
+       else if (!new_plane_state->visible)
+               return 0;
 
        fi = drm_format_info(DRM_FORMAT_R1);
        if (!fi)
@@ -619,6 +629,15 @@ static int 
ssd130x_primary_plane_helper_atomic_check(struct drm_plane *plane,
 
        pitch = drm_format_info_min_pitch(fi, 0, ssd130x->width);
 
+       if (new_plane_state->fb->format != fi) {
+               void *buf;
+
+               /* format conversion necessary; reserve buffer */
+               buf = drm_xfrm_buf_reserve(&ssd130x->xfrm, pitch, GFP_KERNEL);
+               if (!buf)
+                       return -ENOMEM;
+       }
+
        ssd130x_state->buffer = kcalloc(pitch, ssd130x->height, GFP_KERNEL);
        if (!ssd130x_state->buffer)
                return -ENOMEM;
-- 
2.42.0