linux-kernel - Re: [PATCH 7/7] clk: zynqmp: Fix fractional clock check

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Date:   Thu, 21 Nov 2019 15:41:34 +0100
From:   Michael Tretter <m.tretter@...gutronix.de>
To:     Rajan Vaja <rajan.vaja@...inx.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org, robh+dt@...nel.org,
        mark.rutland@....com, michal.simek@...inx.com,
        jolly.shah@...inx.com, dan.carpenter@...cle.com,
        gustavo@...eddedor.com, tejas.patel@...inx.com,
        nava.manne@...inx.com, ravi.patel@...inx.com,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kernel@...gutronix.de, m.tretter@...gutronix.de
Subject: Re: [PATCH 7/7] clk: zynqmp: Fix fractional clock check

On Tue, 12 Nov 2019 05:16:20 -0800, Rajan Vaja wrote:
> Firmware driver sets BIT(4) to BIT(7) as custom type flags. To make
> divider as fractional divider firmware sets BIT(4). So add support
> for custom type flag and use BIT(4) of custom type flag as CLOCK_FRAC
> bit.
> 
> Add a new field to the clock_topology to store custom type flags.
> 
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> ---
>  drivers/clk/zynqmp/clk-zynqmp.h | 1 +
>  drivers/clk/zynqmp/clkc.c       | 4 ++++
>  drivers/clk/zynqmp/divider.c    | 7 +++----
>  3 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/clk/zynqmp/clk-zynqmp.h b/drivers/clk/zynqmp/clk-zynqmp.h
> index fec9a15..5beeb41 100644
> --- a/drivers/clk/zynqmp/clk-zynqmp.h
> +++ b/drivers/clk/zynqmp/clk-zynqmp.h
> @@ -30,6 +30,7 @@ struct clock_topology {
>  	u32 type;
>  	u32 flag;
>  	u32 type_flag;
> +	u8 custom_type_flag;
>  };
>  
>  struct clk_hw *zynqmp_clk_register_pll(const char *name, u32 clk_id,
> diff --git a/drivers/clk/zynqmp/clkc.c b/drivers/clk/zynqmp/clkc.c
> index 10e89f2..4dd8413 100644
> --- a/drivers/clk/zynqmp/clkc.c
> +++ b/drivers/clk/zynqmp/clkc.c
> @@ -84,6 +84,7 @@ struct name_resp {
>  
>  struct topology_resp {
>  #define CLK_TOPOLOGY_TYPE		GENMASK(3, 0)
> +#define CLK_TOPOLOGY_CUSTOM_TYPE_FLAGS	GENMASK(7, 4)
>  #define CLK_TOPOLOGY_FLAGS		GENMASK(23, 8)
>  #define CLK_TOPOLOGY_TYPE_FLAGS		GENMASK(31, 24)
>  	u32 topology[CLK_GET_TOPOLOGY_RESP_WORDS];
> @@ -396,6 +397,9 @@ static int __zynqmp_clock_get_topology(struct clock_topology *topology,
>  		topology[*nnodes].type_flag =
>  				FIELD_GET(CLK_TOPOLOGY_TYPE_FLAGS,
>  					  response->topology[i]);
> +		topology[*nnodes].custom_type_flag =
> +			FIELD_GET(CLK_TOPOLOGY_CUSTOM_TYPE_FLAGS,
> +				  response->topology[i]);
>  		(*nnodes)++;
>  	}
>  
> diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
> index 67aa88c..e700504 100644
> --- a/drivers/clk/zynqmp/divider.c
> +++ b/drivers/clk/zynqmp/divider.c
> @@ -25,7 +25,7 @@
>  #define to_zynqmp_clk_divider(_hw)		\
>  	container_of(_hw, struct zynqmp_clk_divider, hw)
>  
> -#define CLK_FRAC	BIT(13) /* has a fractional parent */
> +#define CLK_FRAC	BIT(4) /* has a fractional parent */

Still NACK. This breaks the compatibility with the mainline TF-A. The
bit is now a different from the bit than in the previous version of
that patch. Moving the flag to custom_type_flags is fine, but please
make sure that you stay backwards compatible to existing versions of the
TF-A.

Michael

>  
>  /**
>   * struct zynqmp_clk_divider - adjustable divider clock
> @@ -279,13 +279,12 @@ struct clk_hw *zynqmp_clk_register_divider(const char *name,
>  
>  	init.name = name;
>  	init.ops = &zynqmp_clk_divider_ops;
> -	/* CLK_FRAC is not defined in the common clk framework */
> -	init.flags = nodes->flag & ~CLK_FRAC;
> +	init.flags = nodes->flag;
>  	init.parent_names = parents;
>  	init.num_parents = 1;
>  
>  	/* struct clk_divider assignments */
> -	div->is_frac = !!(nodes->flag & CLK_FRAC);
> +	div->is_frac = !!(nodes->custom_type_flag & CLK_FRAC);
>  	div->flags = nodes->type_flag;
>  	div->hw.init = &init;
>  	div->clk_id = clk_id;