linux-kernel - Re: [PATCH v2 2/3] clk: xilinx: vcu: don't set pll

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Message-ID: <CAMuHMdV9iZK3FOXhSmvvxK=HqBe3hUnNcZZ2aL1G--XHFgN07A@mail.gmail.com>
Date: Thu, 2 Jan 2025 20:28:09 +0100
From: Geert Uytterhoeven <geert@...ux-m68k.org>
To: Rohit Visavalia <rohit.visavalia@....com>
Cc: mturquette@...libre.com, sboyd@...nel.org, michal.simek@....com, 
	vishal.sagar@....com, javier.carrasco.cruz@...il.com, geert+renesas@...der.be, 
	u.kleine-koenig@...libre.com, linux-clk@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/3] clk: xilinx: vcu: don't set pll_ref as parent of
 VCU(enc/dec) clocks

Hi Rohit,

On Thu, Jan 2, 2025 at 6:04 PM Rohit Visavalia <rohit.visavalia@....com> wrote:
> CCF will try to adjust parent clock to set desire clock frequency of
> child clock. So if pll_ref is not a fixed-clock then while setting rate
> of enc/dec clocks pll_ref may get change, which may make VCU malfunction.
>
> Signed-off-by: Rohit Visavalia <rohit.visavalia@....com>
> ---
> Changes in v2:
>   - none
>   - Link to v1: https://lore.kernel.org/linux-clk/20241226122023.3439559-3-rohit.visavalia@amd.com
> ---
>  drivers/clk/xilinx/xlnx_vcu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clk/xilinx/xlnx_vcu.c b/drivers/clk/xilinx/xlnx_vcu.c
> index 88b3fd8250c2..c520ae1ba65e 100644
> --- a/drivers/clk/xilinx/xlnx_vcu.c
> +++ b/drivers/clk/xilinx/xlnx_vcu.c
> @@ -547,7 +547,7 @@ static int xvcu_register_clock_provider(struct xvcu_device *xvcu)
>                 return PTR_ERR(hw);
>         xvcu->pll_post = hw;
>
> -       parent_data[0].fw_name = "pll_ref";
> +       parent_data[0].fw_name = "dummy_name";
>         parent_data[1].hw = xvcu->pll_post;
>
>         hws[CLK_XVCU_ENC_CORE] =

You completely ignored Stephen's comment, which suggests to not pas
CLK_SET_RATE_PARENT instead (see xvcu_clk_hw_register_leaf()).

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds