linux-kernel - Re: [PATCH] clk: zynqmp: Add support for custom type flags

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Date:   Thu, 7 Nov 2019 17:49:28 +0100
From:   Michael Tretter <m.tretter@...gutronix.de>
To:     Rajan Vaja <rajan.vaja@...inx.com>
Cc:     mturquette@...libre.com, sboyd@...nel.org, michal.simek@...inx.com,
        jolly.shah@...inx.com, dan.carpenter@...cle.com,
        gustavo@...eddedor.com, linux-clk@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de
Subject: Re: [PATCH] clk: zynqmp: Add support for custom type flags

On Thu, 07 Nov 2019 00:58:06 -0800, Rajan Vaja wrote:
> Store extra custom type flags received from firmware.
> 
> Signed-off-by: Rajan Vaja <rajan.vaja@...inx.com>
> Signed-off-by: Jolly Shah <jolly.shah@...inx.com>
> Signed-off-by: Michal Simek <michal.simek@...inx.com>
> ---
>  drivers/clk/zynqmp/clkc.c    | 8 +++++++-
>  drivers/clk/zynqmp/divider.c | 4 ++--
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/clk/zynqmp/clkc.c b/drivers/clk/zynqmp/clkc.c
> index a11f93e..0dea55e 100644
> --- a/drivers/clk/zynqmp/clkc.c
> +++ b/drivers/clk/zynqmp/clkc.c
> @@ -2,7 +2,7 @@
>  /*
>   * Zynq UltraScale+ MPSoC clock controller
>   *
> - *  Copyright (C) 2016-2018 Xilinx
> + *  Copyright (C) 2016-2019 Xilinx
>   *
>   * Based on drivers/clk/zynq/clkc.c
>   */
> @@ -86,6 +86,8 @@ struct topology_resp {
>  #define CLK_TOPOLOGY_TYPE		GENMASK(3, 0)
>  #define CLK_TOPOLOGY_FLAGS		GENMASK(23, 8)
>  #define CLK_TOPOLOGY_TYPE_FLAGS		GENMASK(31, 24)
> +#define CLK_TOPOLOGY_TYPE_FLAG2		GENMASK(7, 4)

What kind of function do these flags indicate? The name is really not
obvious to me.

I would prefer if the defines are kept in the order of the bits in the
field, i.e., the new define should go between CLK_TOPOLOGY_TYPE and
CLK_TOPOLOGY_FLAGS.

> +#define CLK_TOPOLOGY_TYPE_FLAG_BITS	8
>  	u32 topology[CLK_GET_TOPOLOGY_RESP_WORDS];
>  };
>  
> @@ -396,6 +398,10 @@ 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].type_flag |=
> +			FIELD_GET(CLK_TOPOLOGY_TYPE_FLAG2,
> +				  response->topology[i]) <<
> +			CLK_TOPOLOGY_TYPE_FLAG_BITS;

Shifting the new flags into the existing type_flag field seems like a
source for code that is really difficult to read. Maybe use a new field
in the topology for the new flags with a proper name?

>  		(*nnodes)++;
>  	}
>  
> diff --git a/drivers/clk/zynqmp/divider.c b/drivers/clk/zynqmp/divider.c
> index d8f5b70d..d376529 100644
> --- a/drivers/clk/zynqmp/divider.c
> +++ b/drivers/clk/zynqmp/divider.c
> @@ -2,7 +2,7 @@
>  /*
>   * Zynq UltraScale+ MPSoC Divider support
>   *
> - *  Copyright (C) 2016-2018 Xilinx
> + *  Copyright (C) 2016-2019 Xilinx
>   *
>   * Adjustable divider clock implementation
>   */
> @@ -37,7 +37,7 @@
>   */
>  struct zynqmp_clk_divider {
>  	struct clk_hw hw;
> -	u8 flags;
> +	u16 flags;

This change looks unrelated to the remaining patch.

Michael

>  	bool is_frac;
>  	u32 clk_id;
>  	u32 div_type;