[PATCH v5 01/44] dt-bindings: clock: Add new bindings for TI Davinci PLL clocks

[David Lechner]

On 01/16/2018 06:21 AM, Adam Ford wrote:
> On Tue, Jan 16, 2018 at 5:22 AM, Sekhar Nori <nsekhar at ti.com> wrote:
>> Hi Adam, David,
>>
>> On Friday 12 January 2018 03:04 AM, Adam Ford wrote:
>>> Thanks for clarifying.  I was able to make it work with the following patch:
>>>
>>> diff --git a/drivers/clk/davinci/psc-da850.c b/drivers/clk/davinci/psc-da850.c
>>> index 3b4583d..a76b8682 100644
>>> --- a/drivers/clk/davinci/psc-da850.c
>>> +++ b/drivers/clk/davinci/psc-da850.c
>>> @@ -25,7 +25,7 @@ static const struct davinci_psc_clk_info
>>> da850_psc0_info[] __initconst = {
>>>          LPSC(9, 0, uart0, pll0_sysclk2, 0),
>>>          LPSC(13, 0, pruss, pll0_sysclk2, 0),
>>>          LPSC(14, 0, arm, pll0_sysclk6, LPSC_ALWAYS_ENABLED),
>>> -       LPSC(15, 1, dsp, pll0_sysclk1, LPSC_FORCE | LPSC_LOCAL_RESET),
>>> +       LPSC(15, 1, dsp, pll0_sysclk1, LPSC_FORCE | LPSC_LOCAL_RESET |
>>> LPSC_ALWAYS_ENABLED),
>>
>> Keeping the DSP clock always enabled was not needed earlier AFAICS, so
>> this needs to be investigated.
> 
> I was testing the DA850-evm and found it was required or the DA850
> wouldn't boot.  I don't know enough of why to explain it.  I went
> through all the clocks as suggested by David, and this one-line patch
> fixed the hanging problem I had.  Without it the AM1808 board I have
> won't boot.

That's interesting because 1) the AM1808 does not have a DSP and 2) I
am using an AM1808 based system as well that boots without having this
always enabled (AM1808BZWT4 to be exact).

I guess I will leave this change out of the next revision so that we
don't forget that this needs to be addressed. Sekhar found a bug in
the new PSC driver with the LPSC_FORCE bit, so maybe that could be
the difference.

Adam, before the changes in this series, did you have
CONFIG_DAVINCI_RESET_CLOCKS=y in your config?