Re: [ANNOUNCE] v5.2.9-rt3

From: Alexandre Belloni
Date: Tue Aug 20 2019 - 11:44:23 EST


On 19/08/2019 13:03:51+0200, Alexander Dahl wrote:
> Hei hei,
> just tried to compile this v5.2.9-rt3 for SAMA5D27-SOM1-EK1 based on
> arch/arm/configs/sama5_defconfig and with running oldconfig and selecting
> defaults, but that fails if CONFIG_ATMEL_TCB_CLKSRC_USE_SLOW_CLOCK is not set.
> I think this is due to changes for Atmel TCLIB in v5.2 and the not yet adapted
> RT patch "clocksource: TCLIB: Allow higher clock rates for clock events",
> right?

Patch clocksource-tclib-allow-higher-clockrates.patch needs to be
changed so:

ret = setup_clkevents(tc, best_divisor_idx);


ret = setup_clkevents(&tc, best_divisor_idx);

Also, I would think clocksource-tclib-add-proper-depend.patch could be
dropped. Instead, setup_clkevents should use atmel_tcb_divisors. It
would then be necessary to move its declaration before the function.

Sebastian, can you take care of that or do you expect a patch? In the
latter case, do you want a patch for the patch?

> What's the recommended setting of this option for RT?

Using the slow clock, will make the platform wakeup less frequently,
having a higher clock rate will give a better clockevent resolution.

Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering