[U-Boot] [U-Boot, v2, 4/4] arm: am33xx: Add support for mulitiple PLL input frequencies

[Robert Nelson]

On Thu, Jun 8, 2017 at 7:45 PM, Tom Rini <trini at konsulko.com> wrote:
> On Thu, Jun 08, 2017 at 10:17:09AM +0530, Lokesh Vutla wrote:
>>
>>
>> On Thursday 08 June 2017 12:20 AM, Emmanuel Vadot wrote:
>> > On Fri, 12 May 2017 13:20:50 -0400
>> > Tom Rini <trini at konsulko.com> wrote:
>> >
>> >> On Fri, May 05, 2017 at 12:59:10PM +0530, Lokesh Vutla wrote:
>> >>
>> >>> am335x supports various sysclk frequencies which can be determined
>> >>> using sysboot pins. PLLs should be configures based on this
>> >>> sysclk frequency. Add PLL configurations for all supported
>> >>> frequencies.
>> >>>
>> >>> Signed-off-by: Lokesh Vutla <lokeshvutla at ti.com>
>> >>> Reviewed-by: Tom Rini <trini at konsulko.com>
>> >>
>> >> Applied to u-boot/master, thanks!
>> >>
>> >> --
>> >> Tom
>> >
>> >  Hello,
>> >
>> >  This appears to break beaglebone black support, reverting this commit
>> > make u-boot works again.
>>
>> hmm..I see the problem. Here we are hard coding MPU freq to 1GHz even
>> efuse say it is not supported(I am not sure why this is being done, may
>> be Tom can give more details). Even in kernel I see that cpufreq is
>> reading efuse to determine mpu frequency. Now that we have jitter
>> optimized pll configurations, looks like unsupported freq is causing an
>> issue. Can you see if the below patch helps?
>
> Well, in the kernel, did anyone poke the Beagleboard folks about this,
> before pushing the change?  There's BBB shipping with chips that did not
> have their efuses set, hence the way things were structured in U-Boot.

Part of the fun, most shipping BeagleBone and Varients have the proper
efuse'ed silicon nowadays..

I think all my Rev B's (2GB eMMC which all 100% have the non-efused
silicon) are in my up-time test farm at home.  I might have an old one
somewhere here at work.

But yes, all BeagleBone am335x's where pinned at TI for 1Ghz support
before TI started efuse'ing

Regards,

-- 
Robert Nelson
https://rcn-ee.com/