drm/i915/wm: reduce stack usage in skl_print_wm_changes()

When KMSAN is enabled, this function causes has a rather excessive stack usage:

drivers/gpu/drm/i915/display/skl_watermark.c:2977:1: error: stack frame size (1432) exceeds limit (1408) in 'skl_compute_wm' [-Werror,-Wframe-larger-than]

This is apparently all caused by the varargs calls to drm_dbg_kms(). Inlining
this into skl_compute_wm() means that any function called by skl_compute_wm()
has its own stack on top of that.

Move the worst bit into a separate function marked as noinline_for_stack to
limit that to the one code path that actually needs it.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250620113748.3869160-1-arnd@kernel.org
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c b/drivers/gpu/drm/i915/display/skl_watermark.c
index 85327cd627dddd501bc8ce1676cf509b81106cd3..d39fabd09938d549fc1fbbc46ae3e8b3b8cddaf3 100644 (file)
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2676,6 +2676,97 @@ static char enast(bool enable)
        return enable ? '*' : ' ';
 }
 
+static noinline_for_stack void
+skl_print_plane_changes(struct intel_display *display,
+                       struct intel_plane *plane,
+                       const struct skl_plane_wm *old_wm,
+                       const struct skl_plane_wm *new_wm)
+{
+       drm_dbg_kms(display->drm,
+                   "[PLANE:%d:%s]   level %cwm0,%cwm1,%cwm2,%cwm3,%cwm4,%cwm5,%cwm6,%cwm7,%ctwm,%cswm,%cstwm"
+                   " -> %cwm0,%cwm1,%cwm2,%cwm3,%cwm4,%cwm5,%cwm6,%cwm7,%ctwm,%cswm,%cstwm\n",
+                   plane->base.base.id, plane->base.name,
+                   enast(old_wm->wm[0].enable), enast(old_wm->wm[1].enable),
+                   enast(old_wm->wm[2].enable), enast(old_wm->wm[3].enable),
+                   enast(old_wm->wm[4].enable), enast(old_wm->wm[5].enable),
+                   enast(old_wm->wm[6].enable), enast(old_wm->wm[7].enable),
+                   enast(old_wm->trans_wm.enable),
+                   enast(old_wm->sagv.wm0.enable),
+                   enast(old_wm->sagv.trans_wm.enable),
+                   enast(new_wm->wm[0].enable), enast(new_wm->wm[1].enable),
+                   enast(new_wm->wm[2].enable), enast(new_wm->wm[3].enable),
+                   enast(new_wm->wm[4].enable), enast(new_wm->wm[5].enable),
+                   enast(new_wm->wm[6].enable), enast(new_wm->wm[7].enable),
+                   enast(new_wm->trans_wm.enable),
+                   enast(new_wm->sagv.wm0.enable),
+                   enast(new_wm->sagv.trans_wm.enable));
+
+       drm_dbg_kms(display->drm,
+                   "[PLANE:%d:%s]   lines %c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%4d"
+                     " -> %c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%4d\n",
+                   plane->base.base.id, plane->base.name,
+                   enast(old_wm->wm[0].ignore_lines), old_wm->wm[0].lines,
+                   enast(old_wm->wm[1].ignore_lines), old_wm->wm[1].lines,
+                   enast(old_wm->wm[2].ignore_lines), old_wm->wm[2].lines,
+                   enast(old_wm->wm[3].ignore_lines), old_wm->wm[3].lines,
+                   enast(old_wm->wm[4].ignore_lines), old_wm->wm[4].lines,
+                   enast(old_wm->wm[5].ignore_lines), old_wm->wm[5].lines,
+                   enast(old_wm->wm[6].ignore_lines), old_wm->wm[6].lines,
+                   enast(old_wm->wm[7].ignore_lines), old_wm->wm[7].lines,
+                   enast(old_wm->trans_wm.ignore_lines), old_wm->trans_wm.lines,
+                   enast(old_wm->sagv.wm0.ignore_lines), old_wm->sagv.wm0.lines,
+                   enast(old_wm->sagv.trans_wm.ignore_lines), old_wm->sagv.trans_wm.lines,
+                   enast(new_wm->wm[0].ignore_lines), new_wm->wm[0].lines,
+                   enast(new_wm->wm[1].ignore_lines), new_wm->wm[1].lines,
+                   enast(new_wm->wm[2].ignore_lines), new_wm->wm[2].lines,
+                   enast(new_wm->wm[3].ignore_lines), new_wm->wm[3].lines,
+                   enast(new_wm->wm[4].ignore_lines), new_wm->wm[4].lines,
+                   enast(new_wm->wm[5].ignore_lines), new_wm->wm[5].lines,
+                   enast(new_wm->wm[6].ignore_lines), new_wm->wm[6].lines,
+                   enast(new_wm->wm[7].ignore_lines), new_wm->wm[7].lines,
+                   enast(new_wm->trans_wm.ignore_lines), new_wm->trans_wm.lines,
+                   enast(new_wm->sagv.wm0.ignore_lines), new_wm->sagv.wm0.lines,
+                   enast(new_wm->sagv.trans_wm.ignore_lines), new_wm->sagv.trans_wm.lines);
+
+       drm_dbg_kms(display->drm,
+                   "[PLANE:%d:%s]  blocks %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d"
+                   " -> %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d\n",
+                   plane->base.base.id, plane->base.name,
+                   old_wm->wm[0].blocks, old_wm->wm[1].blocks,
+                   old_wm->wm[2].blocks, old_wm->wm[3].blocks,
+                   old_wm->wm[4].blocks, old_wm->wm[5].blocks,
+                   old_wm->wm[6].blocks, old_wm->wm[7].blocks,
+                   old_wm->trans_wm.blocks,
+                   old_wm->sagv.wm0.blocks,
+                   old_wm->sagv.trans_wm.blocks,
+                   new_wm->wm[0].blocks, new_wm->wm[1].blocks,
+                   new_wm->wm[2].blocks, new_wm->wm[3].blocks,
+                   new_wm->wm[4].blocks, new_wm->wm[5].blocks,
+                   new_wm->wm[6].blocks, new_wm->wm[7].blocks,
+                   new_wm->trans_wm.blocks,
+                   new_wm->sagv.wm0.blocks,
+                   new_wm->sagv.trans_wm.blocks);
+
+       drm_dbg_kms(display->drm,
+                   "[PLANE:%d:%s] min_ddb %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d"
+                   " -> %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d\n",
+                   plane->base.base.id, plane->base.name,
+                   old_wm->wm[0].min_ddb_alloc, old_wm->wm[1].min_ddb_alloc,
+                   old_wm->wm[2].min_ddb_alloc, old_wm->wm[3].min_ddb_alloc,
+                   old_wm->wm[4].min_ddb_alloc, old_wm->wm[5].min_ddb_alloc,
+                   old_wm->wm[6].min_ddb_alloc, old_wm->wm[7].min_ddb_alloc,
+                   old_wm->trans_wm.min_ddb_alloc,
+                   old_wm->sagv.wm0.min_ddb_alloc,
+                   old_wm->sagv.trans_wm.min_ddb_alloc,
+                   new_wm->wm[0].min_ddb_alloc, new_wm->wm[1].min_ddb_alloc,
+                   new_wm->wm[2].min_ddb_alloc, new_wm->wm[3].min_ddb_alloc,
+                   new_wm->wm[4].min_ddb_alloc, new_wm->wm[5].min_ddb_alloc,
+                   new_wm->wm[6].min_ddb_alloc, new_wm->wm[7].min_ddb_alloc,
+                   new_wm->trans_wm.min_ddb_alloc,
+                   new_wm->sagv.wm0.min_ddb_alloc,
+                   new_wm->sagv.trans_wm.min_ddb_alloc);
+}
+
 static void
 skl_print_wm_changes(struct intel_atomic_state *state)
 {
@@ -2705,7 +2796,6 @@ skl_print_wm_changes(struct intel_atomic_state *state)
 
                        if (skl_ddb_entry_equal(old, new))
                                continue;
-
                        drm_dbg_kms(display->drm,
                                    "[PLANE:%d:%s] ddb (%4d - %4d) -> (%4d - %4d), size %4d -> %4d\n",
                                    plane->base.base.id, plane->base.name,
@@ -2723,89 +2813,7 @@ skl_print_wm_changes(struct intel_atomic_state *state)
                        if (skl_plane_wm_equals(display, old_wm, new_wm))
                                continue;
 
-                       drm_dbg_kms(display->drm,
-                                   "[PLANE:%d:%s]   level %cwm0,%cwm1,%cwm2,%cwm3,%cwm4,%cwm5,%cwm6,%cwm7,%ctwm,%cswm,%cstwm"
-                                   " -> %cwm0,%cwm1,%cwm2,%cwm3,%cwm4,%cwm5,%cwm6,%cwm7,%ctwm,%cswm,%cstwm\n",
-                                   plane->base.base.id, plane->base.name,
-                                   enast(old_wm->wm[0].enable), enast(old_wm->wm[1].enable),
-                                   enast(old_wm->wm[2].enable), enast(old_wm->wm[3].enable),
-                                   enast(old_wm->wm[4].enable), enast(old_wm->wm[5].enable),
-                                   enast(old_wm->wm[6].enable), enast(old_wm->wm[7].enable),
-                                   enast(old_wm->trans_wm.enable),
-                                   enast(old_wm->sagv.wm0.enable),
-                                   enast(old_wm->sagv.trans_wm.enable),
-                                   enast(new_wm->wm[0].enable), enast(new_wm->wm[1].enable),
-                                   enast(new_wm->wm[2].enable), enast(new_wm->wm[3].enable),
-                                   enast(new_wm->wm[4].enable), enast(new_wm->wm[5].enable),
-                                   enast(new_wm->wm[6].enable), enast(new_wm->wm[7].enable),
-                                   enast(new_wm->trans_wm.enable),
-                                   enast(new_wm->sagv.wm0.enable),
-                                   enast(new_wm->sagv.trans_wm.enable));
-
-                       drm_dbg_kms(display->drm,
-                                   "[PLANE:%d:%s]   lines %c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%4d"
-                                     " -> %c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%3d,%c%4d\n",
-                                   plane->base.base.id, plane->base.name,
-                                   enast(old_wm->wm[0].ignore_lines), old_wm->wm[0].lines,
-                                   enast(old_wm->wm[1].ignore_lines), old_wm->wm[1].lines,
-                                   enast(old_wm->wm[2].ignore_lines), old_wm->wm[2].lines,
-                                   enast(old_wm->wm[3].ignore_lines), old_wm->wm[3].lines,
-                                   enast(old_wm->wm[4].ignore_lines), old_wm->wm[4].lines,
-                                   enast(old_wm->wm[5].ignore_lines), old_wm->wm[5].lines,
-                                   enast(old_wm->wm[6].ignore_lines), old_wm->wm[6].lines,
-                                   enast(old_wm->wm[7].ignore_lines), old_wm->wm[7].lines,
-                                   enast(old_wm->trans_wm.ignore_lines), old_wm->trans_wm.lines,
-                                   enast(old_wm->sagv.wm0.ignore_lines), old_wm->sagv.wm0.lines,
-                                   enast(old_wm->sagv.trans_wm.ignore_lines), old_wm->sagv.trans_wm.lines,
-                                   enast(new_wm->wm[0].ignore_lines), new_wm->wm[0].lines,
-                                   enast(new_wm->wm[1].ignore_lines), new_wm->wm[1].lines,
-                                   enast(new_wm->wm[2].ignore_lines), new_wm->wm[2].lines,
-                                   enast(new_wm->wm[3].ignore_lines), new_wm->wm[3].lines,
-                                   enast(new_wm->wm[4].ignore_lines), new_wm->wm[4].lines,
-                                   enast(new_wm->wm[5].ignore_lines), new_wm->wm[5].lines,
-                                   enast(new_wm->wm[6].ignore_lines), new_wm->wm[6].lines,
-                                   enast(new_wm->wm[7].ignore_lines), new_wm->wm[7].lines,
-                                   enast(new_wm->trans_wm.ignore_lines), new_wm->trans_wm.lines,
-                                   enast(new_wm->sagv.wm0.ignore_lines), new_wm->sagv.wm0.lines,
-                                   enast(new_wm->sagv.trans_wm.ignore_lines), new_wm->sagv.trans_wm.lines);
-
-                       drm_dbg_kms(display->drm,
-                                   "[PLANE:%d:%s]  blocks %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d"
-                                   " -> %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d\n",
-                                   plane->base.base.id, plane->base.name,
-                                   old_wm->wm[0].blocks, old_wm->wm[1].blocks,
-                                   old_wm->wm[2].blocks, old_wm->wm[3].blocks,
-                                   old_wm->wm[4].blocks, old_wm->wm[5].blocks,
-                                   old_wm->wm[6].blocks, old_wm->wm[7].blocks,
-                                   old_wm->trans_wm.blocks,
-                                   old_wm->sagv.wm0.blocks,
-                                   old_wm->sagv.trans_wm.blocks,
-                                   new_wm->wm[0].blocks, new_wm->wm[1].blocks,
-                                   new_wm->wm[2].blocks, new_wm->wm[3].blocks,
-                                   new_wm->wm[4].blocks, new_wm->wm[5].blocks,
-                                   new_wm->wm[6].blocks, new_wm->wm[7].blocks,
-                                   new_wm->trans_wm.blocks,
-                                   new_wm->sagv.wm0.blocks,
-                                   new_wm->sagv.trans_wm.blocks);
-
-                       drm_dbg_kms(display->drm,
-                                   "[PLANE:%d:%s] min_ddb %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d"
-                                   " -> %4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%4d,%5d\n",
-                                   plane->base.base.id, plane->base.name,
-                                   old_wm->wm[0].min_ddb_alloc, old_wm->wm[1].min_ddb_alloc,
-                                   old_wm->wm[2].min_ddb_alloc, old_wm->wm[3].min_ddb_alloc,
-                                   old_wm->wm[4].min_ddb_alloc, old_wm->wm[5].min_ddb_alloc,
-                                   old_wm->wm[6].min_ddb_alloc, old_wm->wm[7].min_ddb_alloc,
-                                   old_wm->trans_wm.min_ddb_alloc,
-                                   old_wm->sagv.wm0.min_ddb_alloc,
-                                   old_wm->sagv.trans_wm.min_ddb_alloc,
-                                   new_wm->wm[0].min_ddb_alloc, new_wm->wm[1].min_ddb_alloc,
-                                   new_wm->wm[2].min_ddb_alloc, new_wm->wm[3].min_ddb_alloc,
-                                   new_wm->wm[4].min_ddb_alloc, new_wm->wm[5].min_ddb_alloc,
-                                   new_wm->wm[6].min_ddb_alloc, new_wm->wm[7].min_ddb_alloc,
-                                   new_wm->trans_wm.min_ddb_alloc,
-                                   new_wm->sagv.wm0.min_ddb_alloc,
-                                   new_wm->sagv.trans_wm.min_ddb_alloc);
+                       skl_print_plane_changes(display, plane, old_wm, new_wm);
                }
        }
 }