Hi Neil,
DISCLAIMER: none of these patches is meant to be applied anywhere! their purpose is to document what I found out so far (things that are not documented in any public datasheet that I am aware of).
I was curious and wanted to see if there are any differences between the video IP blocks between Meson8/Meson8b/Meson8m2 and GXBB/GXL/GXM.
after reading your gpu/drm/meson/meson_vclk.c I stumbled across the first problem (which is a big one): the 32-bit SoCs don't have the HHI_VID_PLL_CLK_DIV register. unfortunately there is no documentation in the public S805 datasheet that describes the video clock path on Meson8b. some of the registers that are documented in the GXM datasheet published by Khadas (which also contains a nice video clock tree documentation). so I tried to take a different approach: extending the clock controller driver so I could play around until I could read the clock frequencies set by u-boot (which displays an image on the CVBS output). the result of this is the clock patch from this series, which gives me the following output in /sys/kernel/debug/clk/clk_summary: vid_pll 0 0 648000000 0 0 vid_pll_pre_div 0 0 108000000 0 0 vid_pll_post_sel 0 0 108000000 0 0 vid_pll_post_en 0 0 108000000 0 0 vclk2_sel 0 0 108000000 0 0 vclk2_en0 0 0 108000000 0 0 vclk2_xd0 0 0 54000000 0 0 vclk2_clk_div_en 0 0 54000000 0 0 vclk2_div12 0 0 4500000 0 0 vclk2_div12_en 0 0 4500000 0 0 vclk2_div6 0 0 9000000 0 0 vclk2_div6_en 0 0 9000000 0 0 vclk2_div4 0 0 13500000 0 0 vclk2_div4_en 0 0 13500000 0 0 vclk2_div2 0 0 27000000 0 0 vclk2_div2_en 0 0 27000000 0 0 hdmi_tx_pixel_sel 0 0 27000000 0 0 hdmi_tx_pixel_en 0 0 27000000 0 0 vdac0_sel 0 0 27000000 0 0 vdac0_en 0 0 27000000 0 0 vclk2_div1_en 0 0 54000000 0 0 encl_sel 0 0 54000000 0 0 encl_en 0 0 54000000 0 0 vclk_sel 0 0 108000000 0 0 vclk_en0 0 0 108000000 0 0 vclk_xd0 0 0 27000000 0 0 vclk_clk_div_en 0 0 27000000 0 0 vclk_div12 0 0 2250000 0 0 vclk_div12_en 0 0 2250000 0 0 vclk_div6 0 0 4500000 0 0 vclk_div6_en 0 0 4500000 0 0 vclk_div4 0 0 6750000 0 0 vclk_div4_en 0 0 6750000 0 0 vclk_div2 0 0 13500000 0 0 vclk_div2_en 0 0 13500000 0 0 enci_sel 0 0 13500000 0 0 enci_en 0 0 13500000 0 0 vclk_div1_en 0 0 27000000 0 0 encp_sel 0 0 27000000 0 0 encp_en 0 0 27000000 0 0 enct_sel 0 0 27000000 0 0 enct_en 0 0 27000000 0 0 vid_pll_post_div 0 0 108000000 0 0
I am not sure whether the ENCI clock is supposed to be 27MHz. at least the VDAC0 clock is 27MHz, which is definitely correct (in my opinion ;)) "clkmsr" in u-boot (which I don't trust by the way, but I'll document my results here for the sake of completeness) shows these video related clocks: - [ 216 MHz] VID_PLL_CLK(6) - [ 54 MHz] CTS_ENCP_CLK(8) - [ 54 MHz] CTS_ENCL_CLK(9) - [ 24 MHz] CTS_HDMI_SYS_CLK(19) - [ 27 MHz] CTS_HDMI_TX_PIXEL_CLK(36)
after having fun with the clock driver I discovered that the CVBS output turns black when I boot a kernel with the .dts VPU node. a bit later I found out that we must not overwrite VIU_OSD2_CTRL_STAT with 0 and that some of the code in gpu/drm/meson/meson_vpp.c didn't seem to be compatible with the 32-bit SoCs so I simply "#if 0" that code. even later I found out that the 32-bit SoCs seem to use OSD2 (instead of OSD1) for the CVBS output. a small hack in meson_plane.c and meson_canvas.c later I am now able to send my own images through the CVBS output (colors are slightly incorrect and the image is cut off, but you have to start small: [0])
are you planning to support OSD2 at some point?
Regards Martin
[0] https://abload.de/img/vlcsnap-2018-01-01-22b1uym.png
Martin Blumenstingl (2): gpu: drm: meson: HACK - Meson8/Meson8b/Meson8m2 support - WiP clk: meson: meson8b: add the video clock trees - WiP
.../bindings/display/amlogic,meson-vpu.txt | 18 +- drivers/clk/meson/meson8b.c | 637 +++++++++++++++++++++ drivers/clk/meson/meson8b.h | 7 +- drivers/gpu/drm/meson/meson_canvas.c | 11 + drivers/gpu/drm/meson/meson_canvas.h | 4 +- drivers/gpu/drm/meson/meson_drv.c | 3 + drivers/gpu/drm/meson/meson_plane.c | 5 +- drivers/gpu/drm/meson/meson_vclk.c | 21 +- drivers/gpu/drm/meson/meson_venc_cvbs.c | 5 +- drivers/gpu/drm/meson/meson_viu.c | 5 +- drivers/gpu/drm/meson/meson_vpp.c | 28 + include/dt-bindings/clock/meson8b-clkc.h | 42 ++ 12 files changed, 771 insertions(+), 15 deletions(-)