[PATCH 18/18] [HACK, RFC] clk: rk3568: do not divide dclk_vop0

[Sascha Hauer]

On the rk3568 we have this (simplified) situation:

 .--------.     .-----.    .---------.
-| hpll   |--.--| /n  |----|dclk_vop0|-
 `--------´  |  `-----´    `---------´
             |  .-----.    .---------.
             `--| /m  |----|dclk_vop1|-
             |  `-----´    `---------´
             |             .---------.
             `-------------|hdmi_ref |-
                           `---------´

hpll is the PLL that drives the HDMI reference clock and the pixel
clocks for the different CRTCs (dclk_vop0/1). Between the pixel clocks
and the hpll there are programmable dividers whereas the HDMI reference
clock is directly connected to the hpll.

For the HDMI output to work the pixel clock must be the same as the HDMI
reference clock, hence the dividers must be programmed to 1. Normally a
rate change on dclk_vop0/1 propagates through to the hpll and the clock
framework picks a suitable combination of hpll and divider settings. by
accident it picks a divider setting of 1 for the standard 1080p case,
but other divider settings for most other resolutions leaving the HDMI
port non working.

This patch is not a solution, it merely puts the finger in the wound. We
leave out the divider for the composite clock for dclk_vop0 which then
leaves the divider at the bootloader default setting of 1. I assume
the divider is disturbing only for the HDMI case, but needed for other
outputs. Any thoughts how this can be handled?

Signed-off-by: Sascha Hauer <s.hauer at pengutronix.de>
---
 drivers/clk/rockchip/clk-rk3568.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/rockchip/clk-rk3568.c b/drivers/clk/rockchip/clk-rk3568.c
index 69a9e8069a486..2d04d8253ca22 100644
--- a/drivers/clk/rockchip/clk-rk3568.c
+++ b/drivers/clk/rockchip/clk-rk3568.c
@@ -1038,8 +1038,8 @@ static struct rockchip_clk_branch rk3568_clk_branches[] __initdata = {
 			RK3568_CLKGATE_CON(20), 8, GFLAGS),
 	GATE(HCLK_VOP, "hclk_vop", "hclk_vo", 0,
 			RK3568_CLKGATE_CON(20), 9, GFLAGS),
-	COMPOSITE(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT,
-			RK3568_CLKSEL_CON(39), 10, 2, MFLAGS, 0, 8, DFLAGS,
+	COMPOSITE_NODIV(DCLK_VOP0, "dclk_vop0", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT,
+			RK3568_CLKSEL_CON(39), 10, 2, MFLAGS,
 			RK3568_CLKGATE_CON(20), 10, GFLAGS),
 	COMPOSITE(DCLK_VOP1, "dclk_vop1", hpll_vpll_gpll_cpll_p, CLK_SET_RATE_PARENT | CLK_SET_RATE_NO_REPARENT,
 			RK3568_CLKSEL_CON(40), 10, 2, MFLAGS, 0, 8, DFLAGS,
-- 
2.30.2