[PATCH] ARM: AM33XX: clock: SET_RATE_PARENT in lcd path

[PATCH] ARM: AM33XX: clock: SET_RATE_PARENT in lcd path

[Afzal Mohammed]

LCDC clock node is a one that does not have set rate capability. It
just passes on the rate that is sent downstream by it's parent. While
lcdc clock parent and it's grand parent - dpll_disp_m2_ck and
dpll_disp_ck has the capability to configure rate.

And the default rates provided by LCDC clock's ancestors are not
sufficient to obtain pixel clock for current LCDC use cases, hence
currently display would not work on AM335x SoC's (with driver
modifications in platfrom independent way).

Hence inform clock framework to propogate set rate for LCDC clock as
well as it's parent - dpll_disp_m2_ck. With this change, set rate on
LCDC clock would get propogated till dpll_disp_ck via dpll_disp_m2_ck,
hence allowing the driver (same driver is used in DaVinci too) to set
rates using LCDC clock without worrying about platform dependent clock
details.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
---

Based on v3.8-rc3

 arch/arm/mach-omap2/cclock33xx_data.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/arm/mach-omap2/cclock33xx_data.c b/arch/arm/mach-omap2/cclock33xx_data.c
index ea64ad6..b731216 100644
--- a/arch/arm/mach-omap2/cclock33xx_data.c
+++ b/arch/arm/mach-omap2/cclock33xx_data.c
@@ -284,9 +284,10 @@ DEFINE_STRUCT_CLK(dpll_disp_ck, dpll_core_ck_parents, dpll_ddr_ck_ops);
  * TODO: Add clksel here (sys_clkin, CORE_CLKOUTM6, PER_CLKOUTM2
  * and ALT_CLK1/2)
  */
-DEFINE_CLK_DIVIDER(dpll_disp_m2_ck, "dpll_disp_ck", &dpll_disp_ck, 0x0,
-		   AM33XX_CM_DIV_M2_DPLL_DISP, AM33XX_DPLL_CLKOUT_DIV_SHIFT,
-		   AM33XX_DPLL_CLKOUT_DIV_WIDTH, CLK_DIVIDER_ONE_BASED, NULL);
+DEFINE_CLK_DIVIDER(dpll_disp_m2_ck, "dpll_disp_ck", &dpll_disp_ck,
+		   CLK_SET_RATE_PARENT, AM33XX_CM_DIV_M2_DPLL_DISP,
+		   AM33XX_DPLL_CLKOUT_DIV_SHIFT, AM33XX_DPLL_CLKOUT_DIV_WIDTH,
+		   CLK_DIVIDER_ONE_BASED, NULL);
 
 /* DPLL_PER */
 static struct dpll_data dpll_per_dd = {
@@ -932,6 +933,8 @@ int __init am33xx_clk_init(void)
 		cpu_clkflg = CK_AM33XX;
 	}
 
+	lcd_gclk.flags |= CLK_SET_RATE_PARENT;
+
 	for (c = am33xx_clks; c < am33xx_clks + ARRAY_SIZE(am33xx_clks); c++) {
 		if (c->cpu & cpu_clkflg) {
 			clkdev_add(&c->lk);
-- 
1.7.9.5

Re: [PATCH] ARM: AM33XX: clock: SET_RATE_PARENT in lcd path

[Mike Turquette]

Quoting Afzal Mohammed (2013-01-15 05:34:57)
> LCDC clock node is a one that does not have set rate capability. It
> just passes on the rate that is sent downstream by it's parent. While
> lcdc clock parent and it's grand parent - dpll_disp_m2_ck and
> dpll_disp_ck has the capability to configure rate.
> 
> And the default rates provided by LCDC clock's ancestors are not
> sufficient to obtain pixel clock for current LCDC use cases, hence
> currently display would not work on AM335x SoC's (with driver
> modifications in platfrom independent way).
> 
> Hence inform clock framework to propogate set rate for LCDC clock as
> well as it's parent - dpll_disp_m2_ck. With this change, set rate on
> LCDC clock would get propogated till dpll_disp_ck via dpll_disp_m2_ck,
> hence allowing the driver (same driver is used in DaVinci too) to set
> rates using LCDC clock without worrying about platform dependent clock
> details.
> 
> Signed-off-by: Afzal Mohammed <afzal@ti.com>
> ---
> 
> Based on v3.8-rc3
> 
>  arch/arm/mach-omap2/cclock33xx_data.c |    9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/mach-omap2/cclock33xx_data.c b/arch/arm/mach-omap2/cclock33xx_data.c
> index ea64ad6..b731216 100644
> --- a/arch/arm/mach-omap2/cclock33xx_data.c
> +++ b/arch/arm/mach-omap2/cclock33xx_data.c
> @@ -284,9 +284,10 @@ DEFINE_STRUCT_CLK(dpll_disp_ck, dpll_core_ck_parents, dpll_ddr_ck_ops);
>   * TODO: Add clksel here (sys_clkin, CORE_CLKOUTM6, PER_CLKOUTM2
>   * and ALT_CLK1/2)
>   */
> -DEFINE_CLK_DIVIDER(dpll_disp_m2_ck, "dpll_disp_ck", &dpll_disp_ck, 0x0,
> -                  AM33XX_CM_DIV_M2_DPLL_DISP, AM33XX_DPLL_CLKOUT_DIV_SHIFT,
> -                  AM33XX_DPLL_CLKOUT_DIV_WIDTH, CLK_DIVIDER_ONE_BASED, NULL);
> +DEFINE_CLK_DIVIDER(dpll_disp_m2_ck, "dpll_disp_ck", &dpll_disp_ck,
> +                  CLK_SET_RATE_PARENT, AM33XX_CM_DIV_M2_DPLL_DISP,
> +                  AM33XX_DPLL_CLKOUT_DIV_SHIFT, AM33XX_DPLL_CLKOUT_DIV_WIDTH,
> +                  CLK_DIVIDER_ONE_BASED, NULL);
>  
>  /* DPLL_PER */
>  static struct dpll_data dpll_per_dd = {
> @@ -932,6 +933,8 @@ int __init am33xx_clk_init(void)
>                 cpu_clkflg = CK_AM33XX;
>         }
>  
> +       lcd_gclk.flags |= CLK_SET_RATE_PARENT;
> +

Afzal,

This is a bit hacky.  Someone looking at the definition of struct
lcd_gclk above cannot easily tell that CLK_SET_RATE_PARENT is set below.
Also if other clocks need flags set at a later date then this will
become a big ugly block of flag setting.

I hope to move away from these macros some day, but in the mean time it
might be good to have a DEFINE_STRUCT_CLK_FLAGS macro which adds in an
argument struct clk->flags.

Paul, any thoughts on yet another macro?

Thanks,
Mike

>         for (c = am33xx_clks; c < am33xx_clks + ARRAY_SIZE(am33xx_clks); c++) {
>                 if (c->cpu & cpu_clkflg) {
>                         clkdev_add(&c->lk);
> -- 
> 1.7.9.5
> 
> --
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