Re: [PATCH v3 00/19] drm: starfive: jh7110: Enable display subsystem

Hello Michal,

This new version added some more issues on my fml13v01 board, this time 
2 registers in the VOUT_CRG are misconfigured that were correct in v2, 
namely:

0x295c0004 was 0x00000004 on the previous version but is now 0x00000006
0x295c001c was 0x81000000 on the previous version but is now 0x80000000

xx04 sets a slightly different clock divider, but it doesn't seem to 
matter, display also works with this changed value.

xx1c seems to select the wrong clock mux?

After correcting 0x295c001c (and the ones that I mentioned before in the 
hdmitx block), the display comes to life again.

Not sure why these are changed.

Besides that it works great!

Kind regards,
Maud

On 9/4/26 15:27, Michal Wilczynski wrote:

This series enables the display subsystem on the StarFive JH7110.

The dom_vout block holds the display controller (dc8200), the clock
generator (voutcrg) and the HDMI IP, all inside PD_VOUT. The HDMI IP is
a single register block containing both the controller and the PHY, and
it has a circular clock dependency with voutcrg:

   - the HDMI controller needs pclk/mclk/bclk from voutcrg
   - voutcrg needs the pixel clock for its dc8200 pixel MUXes, and that
     clock is generated by the HDMI PHY

The loop only exists if the HDMI block is treated as one device. The
PHY's reference clock is xin24m, not a voutcrg output, so splitting the
node into a parent plus phy and controller children gives deferred probe
a linear order: hdmi-phy, then voutcrg, then hdmi-controller.

The parent maps the register block and owns the regmap its two children
share. Everything in the region sits behind one NoC port whose clock and
reset gate access to it, inside PD_VOUT, so the vout subsystem node from
the RFC is back and owns those for as long as any child exists.

Patch 10 adds a .mode_valid platform op to inno-hdmi.
inno_hdmi_bridge_mode_valid() checks the pixel clock against
hdmi->refclk, but that clock only exists where a "ref" clock is
described. The JH7110 gets its pixel clock from the PHY, so refclk is
NULL and the check was skipped: unsupported modes were advertised, the
modeset then "succeeded" because the atomic enable path cannot fail, and
the display stayed blank.

Patches 15-17 drop the PHY duplication from the RFC. The JH7110 has the
same Innosilicon PHY as the RK3328, offset by 0x100 because it sits
behind the controller in the shared register block. Patch 15 factors out
the pre-PLL config format, table lookup, determine_rate, recalc_rate and
the pre-PLL programming; patch 16 moves Rockchip onto it; patch 17 adds
the JH7110 driver. Pixel clock tables, post-PLL and analog config stay
SoC specific.

Patch 16 should be a no-op for Rockchip - same writes, same order, same
values - and RK3228, whose pre-PLL is at different addresses, keeps its
own register code and shares only the lookup. I have no Rockchip
hardware, so it is build tested only (arm and riscv). A Tested-by would
help.

The dc8200 driver, th1520 reset controller and inno-hdmi bridge that the
RFC listed as prerequisites are all upstream now, so there are no
out-of-tree dependencies.

Testing
=======

Tested on a VisionFive 2 v1.3B using modetest.

All 42 modes the sink advertises work, with nothing in dmesg. Pixel
clocks run from 25.175 MHz (640x480@59.94) up to 297 MHz
(4096x2160@30), including 3840x2160 and the full 1920x1080 and 1280x720
rate families.

The four modes the RFC reported as broken work now too: 2560x1440@59.95,
2048x1080@60.00, 2048x1080@24.00 and 720x400@70.08.

Before patch 10, four of the advertised modes failed: 1680x1050@59.95
(146.250 MHz), 1400x1050@59.98 (121.750), 1152x864@59.97 (81.768) and
1280x768@60.35 (80.140). Those pixel clocks are not in the PHY pre-PLL
table, so clk_set_rate() returned -EINVAL and the screen stayed black
while userspace saw a successful modeset. They are rejected in
.mode_valid now; the other refresh rates of those resolutions still work.

Every commit builds for riscv, and the Rockchip PHY also for arm.

Notes
=====

The JH7110 has no central MAINTAINERS entry and maintainership is
fragmented, so patch 19 adds one for the display subsystem and I am
happy to help maintain it. The new PHY library lives under drivers/phy/,
already covered by the generic PHY framework entry.

checkpatch warns "does MAINTAINERS need updating?" on the patches adding
files, because that entry comes in patch 19.

Thanks to Icenowy Zheng for the dc8200 driver and for explaining how the
SoC and the display pipeline fit together.

Thanks also to Dominique Belhachemi, who got rid of the vout-subsystem
wrapper and helped with the testing, to Maud Spierings for testing on a
Framework 13 panel, and to Graham Markall for testing
the JH7110 display patches independently and writing up the results:
https://big-grey.co.uk/2026/01/26/testing-starfive-jh7110-display-controller-patches/

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