On Fri, Jan 24, 2025 at 03:12:41PM +0200, Ville Syrjälä wrote: > On Fri, Jan 24, 2025 at 01:59:15PM +0100, Simona Vetter wrote: > > On Fri, Jan 24, 2025 at 02:10:54PM +0200, Ville Syrjälä wrote: > > > On Fri, Jan 24, 2025 at 01:14:18PM +0200, Dmitry Baryshkov wrote: > > > > There are several drivers which attempt to upgrading the commit to the > > > > full mode set from their per-object atomic_check() callbacks without > > > > calling the drm_atomic_helper_check_modeset() or > > > > drm_atomic_helper_check() again (as requested by those functions). > > > > > > I don't really understand why any of that is supposedly necessary. > > > drm_atomic_helper_check_modeset() is really all about the > > > connector routing stuff, so if none of that is changing then there > > > is no point in calling it again. Eg. in i915 we call it just at > > > the start, and later on we flag internal modesets all over the > > > place, but none of those need drm_atomic_helper_check_modeset() > > > because nothing routing related will have changed. > > > > i915 doesn't need this because as you say, it doesn't rely on the atomic > > helper modeset tracking much at all, but it's all internal. This is for > > drivers which rely more or less entirely on > > drm_atomic_crtc_needs_modeset(). > > > > Also note that it's not just about connector routing, but about adding all > > the necessary additional states with > > drm_atomic_add_affected_connectors/planes and re-running all the various > > state computation hooks for those. Again i915 hand-rolls that all. > > IIRC it only runs the connectors' atomic_check(), > nothing else really. But maybe that's changed since I last > looked at it. It also calls encoder's atomic_check() or mode_fixup() callbacks (see the mode_fixup() call at the end of the helper). And the other function, drm_atomic_helper_check() calls drm_atomic_helper_check_modeset() and then calls atomic_check() for the planes and for the CRTCs that are a part of the state. For example, if the the encoder requires a modeset change on the CRTC, then that CRTC (and all connected planes) should also be added to the state. However with the default code flow it's already too late. Even if we just split those functions, it's still too late, as mode_fixup() comes after adding of the CRTC and planes. Likewise, if the plane wants to upgrade the commit, then all other planes blended on the corresponding CRTC must also be added to the state. > Anyways it feels like we're throwing everything and the > kitchen sink into a single function here. Maybe it should be > split into two or more functions with clear responsibilities? I'm not sure, what do you mean. Do you mean splitting those two drm_atomic_helper functions? It is possible, but it will also result in a higher amount of boilerplate code (and still being easy to break). For example, the mentioned depdency series adds this kind of 'oh, do we need a modeset?' call to the DPU driver. But then each other driver needs similar code. I did a quick non-comprehensive grepping (also I skipped i915 and AMDGPU drivers, too complicated to analyse): + malidp, malidp_crtc_atomic_check_gamma(), manually calls drm_atomic_helper_check_modeset() again good citizen + GUD: gud_pipe_check(), plane setting mode_changed, pardoned, single plane on a CRTC + mcde, mcde_display_check(), plane setting mode_changed pardoned, single plane on a CRTC + mgag200, mgag200_primary_plane_helper_atomic_check(), plane setting mode_changed pardoned, single plane on a CRTC + tilcdc, tilcdc_plane_atomic_check() plane setting mode_changed pardoned, single plane on a CRTC + pl111, pl111_display_check(), plane setting mode_changed pardoned, single plane on a CRTC + tve200, tve200_display_check(), plane setting mode_changed pardoned, single plane on a CRTC + IPUv3, ipu_plane_atomic_check(), plane setting mode_changed no excuse, it can come from the overlay plane + ingenic, ingenic_ipu_plane_atomic_check() plane setting mode_changed no idea + ingenic, ingenic_drm_plane_atomic_check(), plane setting mode_changed no idea + nouveau/nv50, nv50_outp_atomic_check_view(), encoder setting mode_changed no idea of the possible impact + msm, dpu_encoder_virt_atomic_check() encoder setting mode_changed possible issues once resource allocation is moved to CRTC + imx/lcdcl: imx_lcdc_pipe_update(), ignores crtc_state->mode_changed, forces mode_set on its own no excuse? needs to be refactored anyway? + meson, meson_encoder_hdmi_atomic_check() bridge setting mode_changed no idea of the possible impact + nwl-dsp, nwl_dsi_bridge_atomic_check() bridge upgrading active_changed to mode_changed no idea of the possible impact + drm_atomic_helper_connector_tv_check() connector setting mode_changed should be okay... + drm_atomic_helper_connector_hdmi_check() connector setting mode_changed should be okay... + cadence, cdns_mhdp_connector_atomic_check() connector setting mode_changed should be okay... + synopsis, dw_hdmi_connector_atomic_check connector setting mode_changed should be okay... + vc4, vc4_hdmi_connector_atomic_check() connector setting mode_changed should be okay... + vmwgfx, vmw_stdu_connector_atomic_check() connector setting mode_changed should be okay... + msm, dpu_crtc_atomic_check() CRTC upgrading active_changed to mode_changed patch pending + drm_dp_mst_add_affected_dsc_crtcs() when is it supposed to be called at all? Please note, that those 'pardoned' or 'should be okay' drivers are breaking the defined function API and might stop functioning at some point. > > > > > So yeah i915 doesn't need this. > > -Sima > > > > > > > > > > > > > As discussed on IRC, add separate atomic_needs_modeset() callbacks, > > > > whose only purpose is to allow the plane, connector, encoder or CRTC to > > > > specify that for whatever reasons corresponding CRTC should undergo a > > > > full modeset. The helpers will call these callbacks in a proper place, > > > > adding affected objects and calling required functions as required. > > > > > > > > The MSM patches depend on the msm-next tree and the series at [1]. The > > > > plan is to land core changes through drm-misc, then merge drm-misc-next > > > > into msm-next and merge remaining msm-specific patches through the > > > > msm-next tree. > > > > > > > > [1] https://lore.kernel.org/dri-devel/20250123-drm-dirty-modeset-v2-0-bbfd3a6cd1a4@xxxxxxxxxx/ > > > > > > > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > > > > --- > > > > Dmitry Baryshkov (6): > > > > drm/atomic-helper: add atomic_needs_modeset callbacks > > > > drm/mgag200: move format check to drm_plane_helper.atomic_needs_modeset > > > > drm/msm/dpu: stop upgrading commits by enabling allow_modeset > > > > drm/msm/dpu: move CTM check to drm_crtc_helper.atomic_needs_modeset > > > > drm/msm/dpu: use atomic_needs_modeset for CDM check > > > > drm/msm: drop msm_atomic_check wrapper > > > > > > > > drivers/gpu/drm/drm_atomic_helper.c | 59 ++++++++++++++++++ > > > > drivers/gpu/drm/mgag200/mgag200_drv.h | 2 + > > > > drivers/gpu/drm/mgag200/mgag200_mode.c | 27 ++++++--- > > > > drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c | 15 +++++ > > > > drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 44 +++++++++----- > > > > drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 4 -- > > > > drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c | 26 -------- > > > > drivers/gpu/drm/msm/msm_atomic.c | 29 --------- > > > > drivers/gpu/drm/msm/msm_drv.h | 1 - > > > > drivers/gpu/drm/msm/msm_kms.c | 2 +- > > > > drivers/gpu/drm/msm/msm_kms.h | 7 --- > > > > include/drm/drm_modeset_helper_vtables.h | 92 +++++++++++++++++++++++++++++ > > > > 12 files changed, 219 insertions(+), 89 deletions(-) > > > > --- > > > > base-commit: 0936f0e54426177b0f0263ddf806ed5e13487db6 > > > > change-id: 20250123-atomic-needs-modeset-8f6a8243a3f7 > > > > prerequisite-change-id: 20241222-drm-dirty-modeset-88079bd27ae6:v2 > > > > prerequisite-patch-id: 0c61aabfcd13651203f476985380cbf4d3c299e6 > > > > prerequisite-patch-id: c6026f08011c288fd301676e9fa6f46d0cc1dab7 > > > > prerequisite-patch-id: b0cb06d5c88791d6e4755d879ced0d5050aa3cbf > > > > prerequisite-patch-id: fd72ddde9dba0df053113bc505c213961a9760da > > > > > > > > Best regards, > > > > -- > > > > Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx> > > > > > > -- > > > Ville Syrjälä > > > Intel > > > > -- > > Simona Vetter > > Software Engineer, Intel Corporation > > http://blog.ffwll.ch > > -- > Ville Syrjälä > Intel -- With best wishes Dmitry
