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Re: [PATCH 00/58] ARM: at91: rework Atmel TCB drivers

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  Re: [PATCH 00/58] ARM: at91: rework Atmel TCB drivers Thierry Reding <thierry.reding@gmail.com> - 2017-07-06 08:50 +0200

#1682075 — Re: [PATCH 00/58] ARM: at91: rework Atmel TCB drivers

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On Tue, May 30, 2017 at 11:50:41PM +0200, Alexandre Belloni wrote:
> Hi,
> 
> This series reworks the Atmel Timer counter Block drivers. Those blocks
> each have 3 counters with 2 channels each and can be used for
> multiple functions:
>  - timers
>  - PWMs
>  - Quadrature decoders
>  - Stepper motor counters
> 
> Up until now, each TCB was fully used by each driver, possibly wasting
> counters/channels.
> 
> There is a second issue motivating that rework. Until now, the PIT is
> still used to boot then later in the boot sequence, the clocksource is
> switched to the TCB. This ends up not working well with preempt-rt
> because on some SoCs, the PIT interrupt is shared with the DBGU uart.
> When using preempt-rt the interrupt flags for the PIT and the DBGU end
> up being incompatible.
> 
> The rework breaks the DT ABI. Backward compatibility can be kept by
> keeping tcb_clksrc and atmel_tclib but as AVR32 is now gone from the
> kernel, I don't think it makes much sense to keep them.
> 
> Also, there is no other choice than breaking the mainly unused
> pwm-atmel-tcb binding. Only the kizbox is actually using it.
> 
> I think the bindings are now ok and I hope we can take the DT changes
> for 4.13.

Has anyone volunteered to pick this up? What are the dependencies here
and how did you plan to get this merged?

Thierry

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