drm/nouveau: Do not implement mode_set_base_atomic callback

Remove the implementation of the CRTC helper mode_set_base_atomic
from nouveau. It pretends to provide mode setting for kdb debugging,
but has been broken for some time.

Kdb output has been supported only for non-atomic mode setting since
commit 9c79e0b1d096 ("drm/fb-helper: Give up on kgdb for atomic drivers")
from 2017.

While nouveau provides non-atomic mode setting for some devices, kdb
assumes that the GEM buffer object is at a fixed location in video
memory. This has not been the case since
commit 4a16dd9d18a0 ("drm/nouveau/kms: switch to drm fbdev helpers")
from 2022. Fbdev-ttm helpers use a shadow buffer with a movable GEM
buffer object. Triggering kdb does therefore not update the display.

Hence remove the whole kdb support from nouveau.

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Simona Vetter <simona.vetter@ffwll.ch>
Acked-by: Daniel Thompson (RISCstar) <danielt@kernel.org>
Link: https://patch.msgid.link/20251125130634.1080966-3-tzimmermann@suse.de

diff --git a/drivers/gpu/drm/nouveau/dispnv04/crtc.c b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
index c063756eaea3cfcb215d480dab98cf96064a9687..80493224eb6c79a69214302641aacb5135082e25 100644 (file)
--- a/drivers/gpu/drm/nouveau/dispnv04/crtc.c
+++ b/drivers/gpu/drm/nouveau/dispnv04/crtc.c
@@ -837,7 +837,7 @@ nv_crtc_gamma_set(struct drm_crtc *crtc, u16 *r, u16 *g, u16 *b,
 static int
 nv04_crtc_do_mode_set_base(struct drm_crtc *crtc,
                           struct drm_framebuffer *passed_fb,
-                          int x, int y, bool atomic)
+                          int x, int y)
 {
        struct nouveau_crtc *nv_crtc = nouveau_crtc(crtc);
        struct drm_device *dev = crtc->dev;
@@ -850,19 +850,12 @@ nv04_crtc_do_mode_set_base(struct drm_crtc *crtc,
        NV_DEBUG(drm, "index %d\n", nv_crtc->index);
 
        /* no fb bound */
-       if (!atomic && !crtc->primary->fb) {
+       if (!crtc->primary->fb) {
                NV_DEBUG(drm, "No FB bound\n");
                return 0;
        }
 
-       /* If atomic, we want to switch to the fb we were passed, so
-        * now we update pointers to do that.
-        */
-       if (atomic) {
-               drm_fb = passed_fb;
-       } else {
-               drm_fb = crtc->primary->fb;
-       }
+       drm_fb = crtc->primary->fb;
 
        nvbo = nouveau_gem_object(drm_fb->obj[0]);
        nv_crtc->fb.offset = nvbo->offset;
@@ -920,15 +913,7 @@ nv04_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y,
        int ret = nv_crtc_swap_fbs(crtc, old_fb);
        if (ret)
                return ret;
-       return nv04_crtc_do_mode_set_base(crtc, old_fb, x, y, false);
-}
-
-static int
-nv04_crtc_mode_set_base_atomic(struct drm_crtc *crtc,
-                              struct drm_framebuffer *fb,
-                              int x, int y, enum mode_set_atomic state)
-{
-       return nv04_crtc_do_mode_set_base(crtc, fb, x, y, true);
+       return nv04_crtc_do_mode_set_base(crtc, old_fb, x, y);
 }
 
 static void nv04_cursor_upload(struct drm_device *dev, struct nouveau_bo *src,
@@ -1274,7 +1259,6 @@ static const struct drm_crtc_helper_funcs nv04_crtc_helper_funcs = {
        .commit = nv_crtc_commit,
        .mode_set = nv_crtc_mode_set,
        .mode_set_base = nv04_crtc_mode_set_base,
-       .mode_set_base_atomic = nv04_crtc_mode_set_base_atomic,
        .disable = nv_crtc_disable,
        .get_scanout_position = nouveau_display_scanoutpos,
 };