[Letux-kernel] [PATCH RFC 0/2] mach-omap2: handle autoidle denial

Tero Kristo t-kristo at ti.com
Thu Oct 4 16:42:25 CEST 2018


On 04/10/18 17:25, Tony Lindgren wrote:
> * Andreas Kemnade <andreas at kemnade.info> [181004 05:56]:
>> On the gta04 with a dm3730 omap_hdq does not work properly when the
>> device enters lower power states. Idling uart1 and 2 is enough
>> to show up that problem, if there are no other things enabled.
>> Further research reveals that hdq iclk must not be turned off during
>> transfers, also according to the TRM. That fact is also correctly described
>> in the flags but the code to handle that is incomplete.
>>
>> Since the order is first disable all autoidles, then disable selected
>> and then enable all, we need to either change that order or add
>> a usecount. Since it is done only in init, we could think about changing
>> order.
> 
> These patches look OK to me, assuming Tero will review them more
> closely.

There is no locking whatsoever in the autoidle counting atm, that must 
be fixed otherwise you get races.

> It seems we should just provide a generic interface for
> clk_allow_autoidle() and clk_deny_autoidle()? Otherwise we'll
> be forever stuck with pdata callbacks it seems.

The TI clock driver is actually providing these APIs, so that should be 
fine. I don't think there is any use / need for pdata callbacks atm, it 
just happens hwmod core is calling these at the moment which might have 
confused you.

-Tero
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