On Mon, Sep 22, 2025 at 11:48:26AM +0800, Liu Ying wrote: > On 09/19/2025, Frank Li wrote: > > On Fri, Jul 04, 2025 at 05:03:55PM +0800, Liu Ying wrote: > >> In TCON operation mode, sync signals from FrameGen are ignored, but > >> a much more customized output timing can be generated by the TCON > >> module. By using TCON operaton mode, generate KACHUNK signal along > >> with HSYNC/VSYNC/data enable signals. The KACHUNK signal is used as > >> a synchronization signal inside the prefetch engine(DPRC + PRG(s), > >> attached to FetchUnit(s)). Carefully switch TCON bypass mode to TCON > >> operation mode when CRTC is being enabled so that the prefetch engine > >> may evade the first dumb frame generated by the display controller. > >> > >> Since TCON BYPASS bit is controlled by KMS driver when doing atomic > >> commits, drop the bit setting when initializing TCON. This also > >> avoids accidentally initializing TCON BYPASS bit to 1 when driver > >> module removing and re-installing where an upcoming patch would > >> disable a CRTC at boot in TCON operation mode if needed. > >> > >> Signed-off-by: Liu Ying <[email protected]> > >> --- > >> drivers/gpu/drm/imx/dc/dc-crtc.c | 28 ++++++++++ > >> drivers/gpu/drm/imx/dc/dc-de.h | 2 + > >> drivers/gpu/drm/imx/dc/dc-kms.h | 2 + > >> drivers/gpu/drm/imx/dc/dc-tc.c | 114 > >> +++++++++++++++++++++++++++++++++++++-- > >> 4 files changed, 142 insertions(+), 4 deletions(-) > >> > > ... > >> @@ -249,6 +260,7 @@ dc_crtc_atomic_enable(struct drm_crtc *crtc, struct > >> drm_atomic_state *state) > >> enable_irq(dc_crtc->irq_ed_safe_shdload); > >> > >> dc_fg_cfg_videomode(dc_crtc->fg, adj); > >> + dc_tc_cfg_videomode(dc_crtc->tc, adj); > >> > >> dc_cf_framedimensions(dc_crtc->cf_cont, > >> adj->crtc_hdisplay, adj->crtc_vdisplay); > >> @@ -273,7 +285,22 @@ dc_crtc_atomic_enable(struct drm_crtc *crtc, struct > >> drm_atomic_state *state) > >> dc_ed_pec_sync_trigger(dc_crtc->ed_cont); > >> dc_ed_pec_sync_trigger(dc_crtc->ed_safe); > >> dc_fg_shdtokgen(dc_crtc->fg); > >> + > >> + /* Don't relinquish CPU until TCON is set to operation mode. */ > >> + local_irq_save(flags); > >> + preempt_disable(); > >> + > >> dc_fg_enable(dc_crtc->fg); > >> + /* > >> + * Turn TCON into operation mode as soon as the first dumb > >> + * frame is generated by DC(we don't relinquish CPU to ensure > >> + * this). This makes DPR/PRG be able to evade the frame. > >> + */ > >> + DC_CRTC_WAIT_FOR_FRAMEGEN_FRAME_INDEX_MOVING(dc_crtc->fg); > >> + dc_tc_set_operation_mode(dc_crtc->tc); > >> + > >> + local_irq_restore(flags); > >> + preempt_enable(); > > > > Does it need reverised order? > > I'm referring to __raw_spin_lock_irqsave() and __raw_spin_unlock_irqrestore() > to do this right, where local IRQ is saved/restored prior to preemption > disablement/enablement. Am I missing anything?
Okay! That should be fine. Frank > > > > >> > >> DC_CRTC_WAIT_FOR_COMPLETION_TIMEOUT(ed_safe_shdload_done); > >> DC_CRTC_WAIT_FOR_COMPLETION_TIMEOUT(ed_cont_shdload_done); > >> @@ -561,6 +588,7 @@ int dc_crtc_init(struct dc_drm_device *dc_drm, int > >> crtc_index) > >> dc_crtc->ed_cont = pe->ed_cont[crtc_index]; > >> dc_crtc->ed_safe = pe->ed_safe[crtc_index]; > >> dc_crtc->fg = de->fg; > >> + dc_crtc->tc = de->tc; > >> > >> dc_crtc->irq_dec_framecomplete = de->irq_framecomplete; > >> dc_crtc->irq_dec_seqcomplete = de->irq_seqcomplete; > >> diff --git a/drivers/gpu/drm/imx/dc/dc-de.h > >> b/drivers/gpu/drm/imx/dc/dc-de.h > >> index > >> 211f3fcc1a9ad642617d3b22e35ea923f75e645b..c39f2ef5eea98c3eb6ae9b5392f9bf9f7e33e7c5 > >> 100644 > >> --- a/drivers/gpu/drm/imx/dc/dc-de.h > >> +++ b/drivers/gpu/drm/imx/dc/dc-de.h > >> @@ -54,6 +54,8 @@ enum drm_mode_status dc_fg_check_clock(struct dc_fg *fg, > >> int clk_khz); > >> void dc_fg_init(struct dc_fg *fg); > >> > > ... > > > >> > >> -- > >> 2.34.1 > >> > > > -- > Regards, > Liu Ying
