The atomic modesetting code tried to distinguish format changes from full modesetting operations. But the implementation was buggy and the format registers were often updated even for simple pageflips.

Fix this problem by distinguishing between format and mode changes; and handle each in it's own branch.

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de Fixes: 4961eb60f145 ("drm/ast: Enable atomic modesetting") Cc: Thomas Zimmermann tzimmermann@suse.de Cc: Gerd Hoffmann kraxel@redhat.com Cc: Dave Airlie airlied@redhat.com Cc: Daniel Vetter daniel.vetter@ffwll.ch Cc: Sam Ravnborg sam@ravnborg.org Cc: Emil Velikov emil.l.velikov@gmail.com Cc: "Y.C. Chen" yc_chen@aspeedtech.com Cc: stable@vger.kernel.org # v5.6+ --- drivers/gpu/drm/ast/ast_mode.c | 52 ++++++++++++++++------------------ 1 file changed, 25 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c index 62fe682a7de6..b129833c0821 100644 --- a/drivers/gpu/drm/ast/ast_mode.c +++ b/drivers/gpu/drm/ast/ast_mode.c @@ -768,34 +768,32 @@ static void ast_crtc_helper_atomic_flush(struct drm_crtc *crtc, { struct drm_device *dev = crtc->dev; struct ast_private *ast = to_ast_private(dev); - struct ast_crtc_state *ast_state; - const struct drm_format_info *format; - struct ast_vbios_mode_info *vbios_mode_info; - struct drm_display_mode *adjusted_mode; - - ast_state = to_ast_crtc_state(crtc->state); - - format = ast_state->format; - if (!format) - return; - - vbios_mode_info = &ast_state->vbios_mode_info; - - ast_set_color_reg(ast, format); - ast_set_vbios_color_reg(ast, format, vbios_mode_info); - - if (!crtc->state->mode_changed) - return; - - adjusted_mode = &crtc->state->adjusted_mode; + struct drm_crtc_state *crtc_state = crtc->state; + struct ast_crtc_state *ast_crtc_state = to_ast_crtc_state(crtc_state); + struct ast_crtc_state *old_ast_crtc_state = + to_ast_crtc_state(old_crtc_state); + const struct drm_format_info *format = ast_crtc_state->format; + struct ast_vbios_mode_info *vbios_mode_info = + &ast_crtc_state->vbios_mode_info; + struct drm_display_mode *adjusted_mode = &crtc_state->adjusted_mode; + + if (drm_WARN_ON_ONCE(dev, !format)) + return; /* BUG: We didn't set format in primary check(). */ + + if (format != old_ast_crtc_state->format) { + ast_set_color_reg(ast, format); + ast_set_vbios_color_reg(ast, format, vbios_mode_info); + }

- ast_set_vbios_mode_reg(ast, adjusted_mode, vbios_mode_info); - ast_set_index_reg(ast, AST_IO_CRTC_PORT, 0xa1, 0x06); - ast_set_std_reg(ast, adjusted_mode, vbios_mode_info); - ast_set_crtc_reg(ast, adjusted_mode, vbios_mode_info); - ast_set_dclk_reg(ast, adjusted_mode, vbios_mode_info); - ast_set_crtthd_reg(ast); - ast_set_sync_reg(ast, adjusted_mode, vbios_mode_info); + if (drm_atomic_crtc_needs_modeset(crtc_state)) { + ast_set_vbios_mode_reg(ast, adjusted_mode, vbios_mode_info); + ast_set_index_reg(ast, AST_IO_CRTC_PORT, 0xa1, 0x06); + ast_set_std_reg(ast, adjusted_mode, vbios_mode_info); + ast_set_crtc_reg(ast, adjusted_mode, vbios_mode_info); + ast_set_dclk_reg(ast, adjusted_mode, vbios_mode_info); + ast_set_crtthd_reg(ast); + ast_set_sync_reg(ast, adjusted_mode, vbios_mode_info); + } }

static void