linux-kernel - Re: [PATCH] clk: ti: clk-7xx: Correct ABE DPLL configuration

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Date:	Mon, 19 May 2014 15:29:35 +0300
From:	Tero Kristo <t-kristo@...com>
To:	Peter Ujfalusi <peter.ujfalusi@...com>,
	Mike Turquette <mturquette@...aro.org>
CC:	Tony Lindgren <tony@...mide.com>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] clk: ti: clk-7xx: Correct ABE DPLL configuration

On 05/06/2014 04:39 PM, Peter Ujfalusi wrote:
> Mike,
>
> On 04/24/2014 06:03 PM, Tero Kristo wrote:
>> On 04/24/2014 12:11 PM, Peter Ujfalusi wrote:
>>> Mike, Tero,
>>>
>>> On 04/03/2014 09:29 AM, Peter Ujfalusi wrote:
>>>> On 04/02/2014 05:12 PM, Tero Kristo wrote:
>>>>> On 04/02/2014 04:48 PM, Peter Ujfalusi wrote:
>>>>>> ABE DPLL frequency need to be lowered from 361267200
>>>>>> to 180633600 to facilitate the ATL requironments.
>>>>>> The dpll_abe_m2x2_ck clock need to be set to double
>>>>>> of ABE DPLL rate in order to have correct clocks
>>>>>> for audio.
>>>>>
>>>>> Do you have some sort of TRM reference for this?
>>>>
>>>> The ATL's max divider is 32.
>>>> For audio purpose the clock coming out from the ATL instance should be
>>>> 128 * fs. It is only possible to have 44.1KHz sampling rate with ABE DPLL set
>>>> to 361267200 or 180633600. Which means:
>>>> The atl generated clock should be 128 * 44100 = 5644800
>>>>   From ABE_DPLL 361267200 we would need to have 64 as divider (ATL can't do
>>>> this).
>>>>   From the suggested ABE_DPLL of 180633600 we can use ATL divider of 32, which
>>>> is the maximum it can do.
>>>>
>>>> So the reason for the change is to have ATLPCLK clock which can be used for
>>>> audio in the future, the 361267200 is just too high.
>>>
>>> Tero: can I have your ack for this patch or do you have further concerns?
>>
>> Yea looks good to me, except for the fact that there is some work on getting
>> default rate/parent support through DT. I would like a comment from Mike about
>> the estimate when this can get in, and whether we should merge intermediate
>> solutions still like this.
>>
>> Anyway, you can consider this patch acked by me, I'll let Mike to decide what
>> to do with it though.
>
> Do you have anything against this patch? Since right now there is no other
> ways to fix the ABE DPLL for dra7 it would be great if we could have this in
> till we have the final solution. Also I'd like to point out that the original
> frequency the ABE DPLL was not correct and renders the audio to be not usable
> on the platform.
>
> Thanks,
> Péter

Thanks, queued for 3.16/ti-clk-drv.

-Tero

>
>>
>> -Tero
>>
>>> Mike: do you want me to resend this patch?
>>>
>>> Thanks,
>>> Péter
>>>
>>>>
>>>>>
>>>>> -Tero
>>>>>
>>>>>>
>>>>>> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
>>>>>> ---
>>>>>>     drivers/clk/ti/clk-7xx.c | 7 ++++++-
>>>>>>     1 file changed, 6 insertions(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/clk/ti/clk-7xx.c b/drivers/clk/ti/clk-7xx.c
>>>>>> index f7e40734c819..19a55bf407dd 100644
>>>>>> --- a/drivers/clk/ti/clk-7xx.c
>>>>>> +++ b/drivers/clk/ti/clk-7xx.c
>>>>>> @@ -16,7 +16,7 @@
>>>>>>     #include <linux/clkdev.h>
>>>>>>     #include <linux/clk/ti.h>
>>>>>>
>>>>>> -#define DRA7_DPLL_ABE_DEFFREQ                361267200
>>>>>> +#define DRA7_DPLL_ABE_DEFFREQ                180633600
>>>>>>     #define DRA7_DPLL_GMAC_DEFFREQ                1000000000
>>>>>>
>>>>>>
>>>>>> @@ -322,6 +322,11 @@ int __init dra7xx_dt_clk_init(void)
>>>>>>         if (rc)
>>>>>>             pr_err("%s: failed to configure ABE DPLL!\n", __func__);
>>>>>>
>>>>>> +    dpll_ck = clk_get_sys(NULL, "dpll_abe_m2x2_ck");
>>>>>> +    rc = clk_set_rate(dpll_ck, DRA7_DPLL_ABE_DEFFREQ * 2);
>>>>>> +    if (rc)
>>>>>> +        pr_err("%s: failed to configure ABE DPLL m2x2!\n", __func__);
>>>>>> +
>>>>>>         dpll_ck = clk_get_sys(NULL, "dpll_gmac_ck");
>>>>>>         rc = clk_set_rate(dpll_ck, DRA7_DPLL_GMAC_DEFFREQ);
>>>>>>         if (rc)
>>>>>>
>>>>>
>>>>
>>>>
>>>
>>
>

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