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Re: [PATCH 1/3] clk: versatile: Switch to assigned clock parents

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  Re: [PATCH 1/3] clk: versatile: Switch to assigned clock parents Pawel Moll <pawel.moll@arm.com> - 2015-08-03 16:10 +0200
    Re: [PATCH 1/3] clk: versatile: Switch to assigned clock parents Stephen Boyd <sboyd@codeaurora.org> - 2015-08-03 20:00 +0200

#1198878 — Re: [PATCH 1/3] clk: versatile: Switch to assigned clock parents

On Sat, 2015-08-01 at 00:44 +0100, Stephen Boyd wrote:
> @@ -179,6 +124,15 @@ static void __init clk_sp810_of_setup(struct device_node *node)
>  		sp810->timerclken[i].channel = i;
>  		sp810->timerclken[i].hw.init = &init;
>  
> +		/*
> +		 * If DT isn't setting the parent, force it to be
> +		 * the 1 MHz clock without going through the framework.
> +		 * We do this before clk_register() so that it can determine
> +		 * the parent and setup the tree properly.
> +		 */
> +		if (deprecated)
> +			init.ops->set_parent(&sp810->timerclken[i].hw, 1);
> +
>  		sp810->timerclken[i].clk = clk_register(NULL,
>  				&sp810->timerclken[i].hw);
>  		WARN_ON(IS_ERR(sp810->timerclken[i].clk));

So that's one thing I've got a (small) problem here...

The above change assumes that SP810 always have 32kHz clock on input 0
and 1MHz clock on input 1. Yes, this is how it made on VExpress, but it
doesn't have to be the case. The magic picking up the faster clock was
added to handle all possible cases.

The bottom line is: if all we care is VExpress than it works, but it's
still a hack. Personally I don't like it, however I won't nak the patch
because of this.

Pawel

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#1199127

On 08/03/2015 07:01 AM, Pawel Moll wrote:
> On Sat, 2015-08-01 at 00:44 +0100, Stephen Boyd wrote:
>> @@ -179,6 +124,15 @@ static void __init clk_sp810_of_setup(struct device_node *node)
>>   		sp810->timerclken[i].channel = i;
>>   		sp810->timerclken[i].hw.init = &init;
>>   
>> +		/*
>> +		 * If DT isn't setting the parent, force it to be
>> +		 * the 1 MHz clock without going through the framework.
>> +		 * We do this before clk_register() so that it can determine
>> +		 * the parent and setup the tree properly.
>> +		 */
>> +		if (deprecated)
>> +			init.ops->set_parent(&sp810->timerclken[i].hw, 1);
>> +
>>   		sp810->timerclken[i].clk = clk_register(NULL,
>>   				&sp810->timerclken[i].hw);
>>   		WARN_ON(IS_ERR(sp810->timerclken[i].clk));
> So that's one thing I've got a (small) problem here...
>
> The above change assumes that SP810 always have 32kHz clock on input 0
> and 1MHz clock on input 1. Yes, this is how it made on VExpress, but it
> doesn't have to be the case. The magic picking up the faster clock was
> added to handle all possible cases.
>
> The bottom line is: if all we care is VExpress than it works, but it's
> still a hack. Personally I don't like it, however I won't nak the patch
> because of this.
>

All current dts files in the kernel tree have 1MHz on input 1, so we 
make this change here to set the parent to input 1 if there isn't an 
assigned-clock-parents property. Presumably new dts files should have 
the new property so that things work properly. I tried to find the 
binding document, but it doesn't look to exist, so I didn't have 
anything to update.


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