linux-kernel - Re: [PATCH v1] platform/x86: pmc

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Date:   Mon, 6 Nov 2017 10:59:41 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Darren Hart <dvhart@...radead.org>,
        platform-driver-x86@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] platform/x86: pmc_atom: Fix parent clocks



On 11/06/2017 08:17 AM, Andy Shevchenko wrote:
> PLL or XTAL is a choice of parents. They are not dependent to
> each other (direct citation):

On Baytrail the PLL takes the 25MHz xtal input and generates a 19.2 MHZ 
Mclk. they are related and completely dependent.

On Cherrytrail, the xtal is 19.2 MHz so there is no need for a PLL mode.

Not sure what you are trying to fix...

>
> 	The source of the frequencies can be XTAL or PLL, depending on
> 	the configuration. Any of the two available frequencies can be
> 	selected for each of the platform clocks.
>
> According to datasheet on hand CherryTrail has them, though they both
> provide 19.2MHz frequency.
>
> Fixes: 282a4e4ce5f9 ("platform/x86: Enable Atom PMC platform clocks")
> Cc: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>   drivers/platform/x86/pmc_atom.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/platform/x86/pmc_atom.c b/drivers/platform/x86/pmc_atom.c
> index 77bac859342d..56734112e5fe 100644
> --- a/drivers/platform/x86/pmc_atom.c
> +++ b/drivers/platform/x86/pmc_atom.c
> @@ -65,7 +65,7 @@ static const struct pmc_clk byt_clks[] = {
>   	{
>   		.name = "pll",
>   		.freq = 19200000,
> -		.parent_name = "xtal",
> +		.parent_name = NULL,
>   	},
>   	{},
>   };
> @@ -76,6 +76,11 @@ static const struct pmc_clk cht_clks[] = {
>   		.freq = 19200000,
>   		.parent_name = NULL,
>   	},
> +	{
> +		.name = "pll",
> +		.freq = 19200000,
> +		.parent_name = NULL,
> +	},
>   	{},
>   };
>