Re: [PATCH] clocksource/drivers/tango-xtal: Replace code by clocksource_mmio_init

From: Daniel Lezcano
Date: Tue Nov 17 2015 - 08:11:42 EST

On 11/17/2015 01:48 PM, Marc Gonzalez wrote:
On 17/11/2015 13:22, Daniel Lezcano wrote:
On 11/13/2015 01:20 PM, Marc Gonzalez wrote:
On 13/11/2015 11:58, Daniel Lezcano wrote:

The current code to initialize, register and read the clocksource is
already factored out in mmio.c via the clocksource_mmio_init function.

Factor out the code with the clocksource_mmio_init function.

The reason I didn't like clocksource_mmio_init() is because it exports
4 generic accessors.

I guess this function makes more sense when all platforms are using it,
in an ARCH_MULTIPLATFORM kernel. (Also the accessors are probably quite
small, so the waste is probably minimal.)

Hi Marc,

it is not clear for me if you agree with this patch or not. Can you
clarify ?

[ Adding rmk as the original mmio.c author ]

Good idea. Russell, the patch is

Hello Daniel,

It's hard to give a straight answer. From my limited perspective (building
a kernel for Sigma boards only) I feel that mmio.c brings nothing. (As you
mentioned, it would be interesting to measure whether having reg_base in
the ctx, rather than as a global is better or worse for perf, though the
actual difference may be lost in the noise.)

On the other hand, I can see how a different perspective, such as yours,
may see benefits in having all drivers use the same APIs; and there may
be other savings for ARCH_MULTIPLATFORM builds with lots of platforms.

IMO, if all the drivers are using the same code, then optimizing it will benefit to all drivers at the same time.

I guess if you think it is a good patch, I will defer to your experience.

Ok, I will wait for Russell comments then.


-- Daniel

I just wish Thomas would take a look at my mmio patch. I will make an
official submission, so that it can be properly shot down :-)

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