[U-Boot] [PATCH] Origen: Correct equation to calculate PLL output frequency

[Rajeshwari Birje]

Hi Minkyu Kang,

As per the user manual I have for EXYNOS5 it is
FOUT = MDIV * FIN / (PDIV * 2^SDIV)

Regards,
Rajeshwari Shinde.

On Mon, Jul 1, 2013 at 1:56 PM, Minkyu Kang <mk7.kang at samsung.com> wrote:
> On 01/07/13 16:42, Rajeshwari Shinde wrote:
>> EXYNOS4 user manual equation for calculating PLL output is
>> FOUT= MDIV x FIN/(PDIV x 2^(SDIV -1))
>> hence updating accordingly.
>>
>> Signed-off-by: Rajeshwari Shinde <rajeshwari.s at samsung.com>
>> ---
>>  arch/arm/cpu/armv7/exynos/clock.c |   11 +++++++++--
>>  1 files changed, 9 insertions(+), 2 deletions(-)
>>
>> diff --git a/arch/arm/cpu/armv7/exynos/clock.c b/arch/arm/cpu/armv7/exynos/clock.c
>> index e1c4246..af0fa5b 100644
>> --- a/arch/arm/cpu/armv7/exynos/clock.c
>> +++ b/arch/arm/cpu/armv7/exynos/clock.c
>> @@ -116,8 +116,15 @@ static int exynos_get_pll_clk(int pllreg, unsigned int r, unsigned int k)
>>               /* FOUT = (MDIV + K / 1024) * FIN / (PDIV * 2^SDIV) */
>>               fout = (m + k / 1024) * (freq / (p * (1 << s)));
>>       } else {
>> -             /* FOUT = MDIV * FIN / (PDIV * 2^SDIV) */
>> -             fout = m * (freq / (p * (1 << s)));
>> +             if (cpu_is_exynos4()) {
>> +                     if (s < 1)
>> +                             s = 1;
>> +                     /* FOUT = MDIV * FIN / (PDIV * 2^(SDIV - 1)) */
>> +                     fout = m * (freq / (p * (1 << (s - 1))));
>> +             } else {
>> +                     /* FOUT = MDIV * FIN / (PDIV * 2^SDIV) */
>> +                     fout = m * (freq / (p * (1 << s)));
>> +             }
>>       }
>>
>>       return fout;
>>
>
> I checked about it.
> It was wrong, but your patch doesn't fit too.
>
> exynos4210
> FOUT = MDIV * FIN / (PDIV * 2^(SDIV - 1))
>
> exynos4412
> FOUT = MDIV * FIN / (PDIV * 2^SDIV)
>
> exynos5250
> FOUT = MDIV * FIN / (PDIV * 2^(SDIV - 1))
>
> At past, our code was,
> FOUT = MDIV * FIN / (PDIV * 2^(SDIV - 1))
> It was changed by Akshay's patch.
>
>
> commit 234370cab4b2f096e095fe8f3284fd39740a4023
> Author: Akshay Saraswat <akshay.s at samsung.com>
> Date:   Fri Mar 22 02:26:36 2013 +0000
>
>     Exynos5: clock: Update the equation to calculate PLL output frequency
>
>     According to the latest exynos5 user manual, the equation for
>     calculating PLL output was changed to
>     FOUT= MDIV x FIN/(PDIV x 2^SDIV)
>     earlier it was
>     FOUT= MDIV x FIN/(PDIV x 2^(SDIV -1))
>     So updating the clock code accordingly.
>
>     Signed-off-by: Hatim Ali <hatim.rv at samsung.com>
>     Signed-off-by: Akshay Saraswat <akshay.s at samsung.com>
>     Acked-by: Simon Glass <sjg at chromium.org>
>
>
> According to Akshay's patch.
> exynos5250 should be
> FOUT = MDIV * FIN / (PDIV * 2^SDIV)
> but my manual (I'm not sure that is latest version) shows
> FOUT = MDIV * FIN / (PDIV * 2^(SDIV - 1))
>
> Akshay,
> please check this.
>
> Rajeshwari,
> Thank you for raise this issue,
> I'll check it and resend the patch.
>
> Thanks,
> Minkyu Kang.
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot



-- 
Regards,
Rajeshwari Shinde