On 18/03/2021 19:16, Jernej Škrabec wrote: > Hi! > > Dne sreda, 17. marec 2021 ob 16:43:34 CET je Maxime Ripard napisal(a): >> Hi, >> >> Here's an attempt at support the HDMI YUV output on the BCM2711 SoC found on >> the RaspberryPi4. >> >> I took the same approach than what dw-hdmi did already, turning a bunch of >> functions found in that driver into helpers since they were fairly generic. >> >> However, it feels a bit clunky overall and there's a few rough edges that >> should be addressed in a generic manner: >> >> - while the format negociation makes sense for a bridge, it feels a bit >> over-engineered for a simple encoder where that setting could be a > simple >> switch (and possibly a property?) > > Property could work, but possible values should be then limited to cross > section of HW and connected display capabilities. > >> >> - more importantly, whether we're choosing an YUV output or not is > completely >> hidden away from the userspace even though it might have some effect on > the >> visual quality output (thinking about YUV420 and YUV422 here mostly). > > IMO driver should select highest achievable quality. So in case of YUV420 and > YUV422, later should be selected. This should be the case even if the property > is implemented. > > Best regards, > Jernej > >> >> - Similarly, the list we report is static and the userspace cannot change > or >> force one mode over the other. We will always pick YUV444 over RGB444 if >> both are available for example. >> >> While the first one might just be due to a lack of helpers, the second and >> third ones are also feeling a bit inconsistent with how we're handling the >> 10/12 bit output for example Another points for YUV422 and YUV420 are: - mandatory YUV420 for pre-HDMI2 displays to achieve 4k60 with HDMI1.4 max TDMS - possibility to achieve factorial frequencies for 10/12bits, it's not the case for YUV422, it's the same TMDS character rate for 8, 19, 12 and 16bits - selecting YUV422 instead of YUV444 for 10/12/16 for 4k60 in HDMI2.0 Today we do not take in account the SCDC feedback from the display, but at some point we should monitor the Scrambling_Status and Character Error Detection to lower down from YUV444 to 422 and 420 for example. Neil >> >> Let me know what you think, >> Maxime >> >> Maxime Ripard (18): >> drm: Introduce new HDMI helpers >> drm/bridge: Add HDMI output fmt helper >> drm/bridge: dw-hdmi: Use helpers >> drm/vc4: txp: Properly set the possible_crtcs mask >> drm/vc4: crtc: Skip the TXP >> drm/vc4: Rework the encoder retrieval code >> drm/vc4: hdmi: Add full range RGB helper >> drm/vc4: hdmi: Use full range helper in csc functions >> drm/vc4: hdmi: Remove limited_rgb_range >> drm/vc4: hdmi: Convert to bridge >> drm/vc4: hdmi: Move XBAR setup to csc_setup >> drm/vc4: hdmi: Replace CSC_CTL hardcoded value by defines >> drm/vc4: hdmi: Define colorspace matrices >> drm/vc4: hdmi: Change CSC callback prototype >> drm/vc4: hdmi: Rework the infoframe prototype >> drm/vc4: hdmi: Support HDMI YUV output >> drm/vc4: hdmi: Move the pixel rate calculation to a helper >> drm/vc4: hdmi: Force YUV422 if the rate is too high >> >> drivers/gpu/drm/Makefile | 2 +- >> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 268 ++------------- >> drivers/gpu/drm/drm_bridge.c | 118 +++++++ >> drivers/gpu/drm/drm_hdmi.c | 170 +++++++++ >> drivers/gpu/drm/vc4/vc4_crtc.c | 59 +++- >> drivers/gpu/drm/vc4/vc4_drv.c | 41 +++ >> drivers/gpu/drm/vc4/vc4_drv.h | 26 +- >> drivers/gpu/drm/vc4/vc4_hdmi.c | 399 +++++++++++++++------- >> drivers/gpu/drm/vc4/vc4_hdmi.h | 13 +- >> drivers/gpu/drm/vc4/vc4_hdmi_regs.h | 6 + >> drivers/gpu/drm/vc4/vc4_regs.h | 19 ++ >> drivers/gpu/drm/vc4/vc4_txp.c | 2 +- >> include/drm/drm_bridge.h | 6 + >> include/drm/drm_hdmi.h | 24 ++ >> 14 files changed, 770 insertions(+), 383 deletions(-) >> create mode 100644 drivers/gpu/drm/drm_hdmi.c >> create mode 100644 include/drm/drm_hdmi.h >> >> -- >> 2.30.2 >> >> > > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
