RE: [PATCH v2 2/3] clk: xilinx: vcu: don't set pll_ref as parent of VCU(enc/dec) clocks

[Visavalia, Rohit]

Hi Geert,

Thank for the review.

>-----Original Message-----
>From: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
>Sent: Friday, January 3, 2025 12:58 AM
>To: Visavalia, Rohit <rohit.visavalia@xxxxxxx>
>Cc: mturquette@xxxxxxxxxxxx; sboyd@xxxxxxxxxx; Simek, Michal
><michal.simek@xxxxxxx>; Sagar, Vishal <vishal.sagar@xxxxxxx>;
>javier.carrasco.cruz@xxxxxxxxx; geert+renesas@xxxxxxxxx; u.kleine-
>koenig@xxxxxxxxxxxx; linux-clk@xxxxxxxxxxxxxxx; linux-arm-
>kernel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>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@xxxxxxx> 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@xxxxxxx>
>> ---
>> Changes in v2:
>>   - none
>>   - Link to v1:
>> https://lore.kernel.org/linux-clk/20241226122023.3439559-3-rohit.visav
>> alia@xxxxxxx
>> ---
>>  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()).

Thanks for pointing this out. Let me take care this in v3 patch series.

>
>Gr{oetje,eeting}s,
>
>                        Geert
>
>--
>Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
>
>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

Thanks
Rohit