Re: [PATCH 2/4] clk: thead: support changing DPU pixel clock rate
From: Icenowy Zheng
Date: Wed Aug 13 2025 - 01:55:08 EST
在 2025-08-13星期三的 10:04 +0800，Troy Mitchell写道：
> On Tue, Aug 12, 2025 at 01:42:56PM +0800, Icenowy Zheng wrote:
> > The DPU pixel clock rate corresponds to the required dot clock of
> > the
> > display mode, so it needs to be tweakable.
> >
> > Add support to change it, by adding generic divider setting code,
> > arming the code to the dpu0/dpu1 clocks, and setting the pixel
> > clock
> > connected to the DPU (after a gate) to CLK_SET_RATE_PARENT to
> > propagate
> > it to the dividers.
> >
> > Signed-off-by: Icenowy Zheng <uwu@xxxxxxxxxx>
> > ---
> > drivers/clk/thead/clk-th1520-ap.c | 87
> > +++++++++++++++++++++++++++++--
> > 1 file changed, 82 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/clk/thead/clk-th1520-ap.c
> > b/drivers/clk/thead/clk-th1520-ap.c
> > index 2f87c7c2c3baf..3e81f3051cd6c 100644
> > --- a/drivers/clk/thead/clk-th1520-ap.c
> > +++ b/drivers/clk/thead/clk-th1520-ap.c
> > @@ -55,6 +55,7 @@ struct ccu_gate {
> >
> > struct ccu_div {
> > u32 enable;
> > + u32 div_en;
> > struct ccu_div_internal div;
> > struct ccu_internal mux;
> > struct ccu_common common;
> > @@ -198,6 +199,78 @@ static unsigned long
> > ccu_div_recalc_rate(struct clk_hw *hw,
> > return rate;
> > }
> >
> > +static long ccu_div_round_rate(struct clk_hw *hw, unsigned long
> > rate,
> > + unsigned long *parent_rate)
> > +{
> > + struct ccu_div *cd = hw_to_ccu_div(hw);
> > + unsigned int val;
> > +
> > + if (!cd->div_en) {
> > + regmap_read(cd->common.map, cd->common.cfg0, &val);
> > + val = val >> cd->div.shift;
> > + val &= GENMASK(cd->div.width - 1, 0);
> > + return divider_ro_round_rate(hw, rate, parent_rate,
> > + NULL, cd->div.width,
> > cd->div.flags,
> > + val);
> > + } else {
> > + return divider_round_rate(hw, rate, parent_rate,
> > + NULL, cd->div.width, cd-
> > >div.flags);
> > + }
> How about this:
> ```
> if (cd->div_en)
> return divider_round_rate(hw, rate, parent_rate,
> NULL, cd->div.width, cd->div.flags);
>
>
> regmap_read(cd->common.map, cd->common.cfg0, &val);
> val = val >> cd->div.shift;
> val &= GENMASK(cd->div.width - 1, 0);
> return divider_ro_round_rate(hw, rate, parent_rate,
> NULL, cd->div.width, cd->div.flags,
> val);
> ```
Sounds quite reasonable.
Although this function is going to hell and next revision of this
patchset will only contain the function below (I will do the change on
that function).
>
> > +}
> > +
> > +static int ccu_div_determine_rate(struct clk_hw *hw,
> > + struct clk_rate_request *req)
> > +{
> > + struct ccu_div *cd = hw_to_ccu_div(hw);
> > + unsigned int val;
> > +
> > + if (!cd->div_en) {
> > + regmap_read(cd->common.map, cd->common.cfg0, &val);
> > + val = val >> cd->div.shift;
> > + val &= GENMASK(cd->div.width - 1, 0);
> > + return divider_ro_determine_rate(hw, req, NULL,
> > + cd->div.width,
> > + cd->div.flags,
> > + val);
> > + } else {
> > + return divider_determine_rate(hw, req, NULL,
> > + cd->div.width, cd-
> > >div.flags);
> ditto.
>
> > + }
> > +}
> > +
> > +static int ccu_div_set_rate(struct clk_hw *hw, unsigned long rate,
> > + unsigned long parent_rate)
> > +{
> > + struct ccu_div *cd = hw_to_ccu_div(hw);
> > + int val = divider_get_val(rate, parent_rate, NULL,
> > + cd->div.width, cd->div.flags);
> > + unsigned int curr_val, reg_val;
> > +
> > + if (val < 0)
> > + return val;
> > +
> > + regmap_read(cd->common.map, cd->common.cfg0, ®_val);
> > + curr_val = reg_val;
> > + curr_val = curr_val >> cd->div.shift;
> > + curr_val &= GENMASK(cd->div.width - 1, 0);
> > +
> > + if (!cd->div_en && curr_val != val)
> > + return -EINVAL;
> > +
> > + reg_val &= ~cd->div_en;
> > + regmap_write(cd->common.map, cd->common.cfg0, reg_val);
> > + udelay(1);
> > +
> > + reg_val &= ~GENMASK(cd->div.width + cd->div.shift - 1, cd-
> > >div.shift);
> > + reg_val |= val << cd->div.shift;
> > + regmap_write(cd->common.map, cd->common.cfg0, reg_val);
> > +
> > + reg_val |= cd->div_en;
> > + regmap_write(cd->common.map, cd->common.cfg0, reg_val);
> > +
> > + return 0;
> > +}
> > +
> > static u8 ccu_div_get_parent(struct clk_hw *hw)
> > {
> > struct ccu_div *cd = hw_to_ccu_div(hw);
> > @@ -240,7 +313,9 @@ static const struct clk_ops ccu_div_ops = {
> > .get_parent = ccu_div_get_parent,
> > .set_parent = ccu_div_set_parent,
> > .recalc_rate = ccu_div_recalc_rate,
> > - .determine_rate = clk_hw_determine_rate_no_reparent,
> > + .round_rate = ccu_div_round_rate,
> > + .set_rate = ccu_div_set_rate,
> > + .determine_rate = ccu_div_determine_rate,
> > };
> >
> > static void ccu_pll_disable(struct clk_hw *hw)
> > @@ -784,6 +859,7 @@ static struct ccu_div venc_clk = {
> > };
> >
> > static struct ccu_div dpu0_clk = {
> > + .div_en = BIT(8),
> > .div = TH_CCU_DIV_FLAGS(0, 8,
> > CLK_DIVIDER_ONE_BASED),
> > .common = {
> > .clkid = CLK_DPU0,
> > @@ -791,7 +867,7 @@ static struct ccu_div dpu0_clk = {
> > .hw.init = CLK_HW_INIT_PARENTS_HW("dpu0",
> > dpu0_pll_clk_parent,
> > &ccu_div_ops,
> > - 0),
> > + CLK_SET_RATE_UNGATE),
> > },
> > };
> >
> > @@ -800,6 +876,7 @@ static const struct clk_parent_data
> > dpu0_clk_pd[] = {
> > };
> >
> > static struct ccu_div dpu1_clk = {
> > + .div_en = BIT(8),
> > .div = TH_CCU_DIV_FLAGS(0, 8,
> > CLK_DIVIDER_ONE_BASED),
> > .common = {
> > .clkid = CLK_DPU1,
> > @@ -807,7 +884,7 @@ static struct ccu_div dpu1_clk = {
> > .hw.init = CLK_HW_INIT_PARENTS_HW("dpu1",
> > dpu1_pll_clk_parent,
> > &ccu_div_ops,
> > - 0),
> > + CLK_SET_RATE_UNGATE),
> > },
> > };
> >
> > @@ -891,9 +968,9 @@ static CCU_GATE(CLK_GPU_CORE, gpu_core_clk,
> > "gpu-core-clk", video_pll_clk_pd,
> > static CCU_GATE(CLK_GPU_CFG_ACLK, gpu_cfg_aclk, "gpu-cfg-aclk",
> > video_pll_clk_pd, 0x0, BIT(4), 0);
> > static CCU_GATE(CLK_DPU_PIXELCLK0, dpu0_pixelclk, "dpu0-pixelclk",
> > - dpu0_clk_pd, 0x0, BIT(5), 0);
> > + dpu0_clk_pd, 0x0, BIT(5), CLK_SET_RATE_PARENT);
> > static CCU_GATE(CLK_DPU_PIXELCLK1, dpu1_pixelclk, "dpu1-pixelclk",
> > - dpu1_clk_pd, 0x0, BIT(6), 0);
> > + dpu1_clk_pd, 0x0, BIT(6), CLK_SET_RATE_PARENT);
> > static CCU_GATE(CLK_DPU_HCLK, dpu_hclk, "dpu-hclk",
> > video_pll_clk_pd, 0x0,
> > BIT(7), 0);
> > static CCU_GATE(CLK_DPU_ACLK, dpu_aclk, "dpu-aclk",
> > video_pll_clk_pd, 0x0,
> > --
> > 2.50.1
> >
> >
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