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

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Message-ID:
 <CH2PR12MB48757F7E82F4FE8C54BFB2DFE50A2@CH2PR12MB4875.namprd12.prod.outlook.com>
Date: Tue, 31 Dec 2024 14:16:23 +0000
From: "Visavalia, Rohit" <rohit.visavalia@....com>
To: Stephen Boyd <sboyd@...nel.org>, "Simek, Michal" <michal.simek@....com>,
	"mturquette@...libre.com" <mturquette@...libre.com>, "Sagar, Vishal"
	<vishal.sagar@....com>
CC: "javier.carrasco.cruz@...il.com" <javier.carrasco.cruz@...il.com>,
	"geert+renesas@...der.be" <geert+renesas@...der.be>,
	"u.kleine-koenig@...libre.com" <u.kleine-koenig@...libre.com>,
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH 2/3] clk: xilinx: vcu: don't set pll_ref as parent of
 VCU(enc/dec) clocks

Hi Stephen,

Thanks for the review.

>-----Original Message-----
>From: Stephen Boyd <sboyd@...nel.org>
>Sent: Tuesday, December 31, 2024 6:06 AM
>To: Visavalia, Rohit <rohit.visavalia@....com>; Simek, Michal
><michal.simek@....com>; mturquette@...libre.com; Sagar, Vishal
><vishal.sagar@....com>
>Cc: 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; Visavalia, Rohit
><rohit.visavalia@....com>
>Subject: Re: [PATCH 2/3] clk: xilinx: vcu: don't set pll_ref as parent of
>VCU(enc/dec) clocks
>
>Quoting Rohit Visavalia (2024-12-26 04:20:22)
>> 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>
>> ---
>>  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 f294a2398cb4..c3a4df7e325a
>> 100644
>> --- a/drivers/clk/xilinx/xlnx_vcu.c
>> +++ b/drivers/clk/xilinx/xlnx_vcu.c
>> @@ -550,7 +550,7 @@ 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";
>
>"dummy_name" isn't part of the binding. It sounds like you want to not set
>CLK_SET_RATE_PARENT flag sometimes?
Yes, if parent rate(pll_ref) has been changed then VCU is not working correctly. So, making name as dummy.

>
>>         parent_data[1].hw = xvcu->pll_post;
>>
>>         hws[CLK_XVCU_ENC_CORE] =

Thanks
Rohit