According to Allwinner's BSP code, in DSI mode, TCON0 clock needs to be
running at what's effectively the per-lane datarate of the DSI link.
Given that the TCON DCLK divider is fixed to 4 (SUN6I_DSI_TCON_DIV),
DCLK can't be set equal to the dotclock. Therefore labeling TCON DCLK
as sun4i_dotclock or tcon-pixel-clock shall be avoided.
With bpp bits per pixel transmitted over n DSI lanes, the target DCLK
rate for a given pixel clock is obtained as follows:
DCLK rate = 1/4 * bpp / n * pixel clock
Effect of this change can be observed through the rate of Vblank IRQs
which should now match refresh rate implied by set display mode. It
was verified to do so on a A64 board with a 2-lane and a 4-lane panel.
v2:
1. prevent reparent of tcon0 to pll-video0-2x
2. include pll-video0 in setting TCON0 DCLK rate
3. tested the whole thing also on a PinePhone
v3:
1. accept that pll-video0 can't be included in setting TCON0 DCLK rate
2. reset pll-video0 to its default rate in case u-boot changed it
Roman Beranek (7):
clk: sunxi-ng: a64: export PLL_MIPI
clk: sunxi-ng: a64: prevent CLK_TCON0 being reparented
arm64: dts: allwinner: a64: assign PLL_MIPI to CLK_TCON0
arm64: dts: allwinner: a64: reset pll-video0 rate
ARM: dts: sunxi: rename tcon's clock output
drm: sun4i: rename sun4i_dotclock to sun4i_tcon_dclk
drm: sun4i: calculate proper DCLK rate for DSI
arch/arm/boot/dts/sun5i.dtsi | 2 +-
arch/arm/boot/dts/sun8i-a23-a33.dtsi | 2 +-
arch/arm/boot/dts/sun8i-a83t.dtsi | 2 +-
arch/arm/boot/dts/sun8i-v3s.dtsi | 2 +-
arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 7 ++-
drivers/clk/sunxi-ng/ccu-sun50i-a64.c | 3 +-
drivers/clk/sunxi-ng/ccu-sun50i-a64.h | 4 +-
drivers/gpu/drm/sun4i/Makefile | 2 +-
drivers/gpu/drm/sun4i/sun4i_tcon.c | 46 +++++++++++--------
.../{sun4i_dotclock.c => sun4i_tcon_dclk.c} | 2 +-
.../{sun4i_dotclock.h => sun4i_tcon_dclk.h} | 0
include/dt-bindings/clock/sun50i-a64-ccu.h | 1 +
12 files changed, 44 insertions(+), 29 deletions(-)
rename drivers/gpu/drm/sun4i/{sun4i_dotclock.c => sun4i_tcon_dclk.c} (99%)
rename drivers/gpu/drm/sun4i/{sun4i_dotclock.h => sun4i_tcon_dclk.h} (100%)
base-commit: 40aeab044a352b9af106960542257c1b9b652e8a
--
2.34.1
