Le 2018-03-31 10:10, Daniel Lezcano a écrit :
On 29/03/2018 16:52, Paul Cercueil wrote:
Le mer. 28 mars 2018 à 18:25, Daniel Lezcano
<daniel.lezcano@xxxxxxxxxx>
a écrit :
On 28/03/2018 17:15, Paul Cercueil wrote:
Le 2018-03-24 07:26, Daniel Lezcano a écrit :
On 18/03/2018 00:29, Paul Cercueil wrote:
This driver will use the TCU (Timer Counter Unit) present on the
Ingenic
JZ47xx SoCs to provide the kernel with a clocksource and timers.
Please provide a more detailed description about the timer.
There's a doc file for that :)
Usually, when there is a new driver I ask for a description in the
changelog for reference.
Where is the clocksource ?
Right, there is no clocksource, just timers.
I don't see the point of using channel idx and pwm checking here.
There is one clockevent, why create multiple channels ? Can't you
stick
to the usual init routine for a timer.
So the idea is that we use all the TCU channels that won't be used
for PWM
as timers. Hence the PWM checking. Why is this bad?
It is not bad but arguable. By checking the channels used by the pwm
in
the code, you introduce an adherence between two subsystems even if
it
is just related to the DT parsing part.
As it is not needed to have more than one timer in the time framework
(at least with the same characteristics), the pwm channels check is
pointless. We can assume the author of the DT file is smart enough to
prevent conflicts and define a pwm and a timer properly instead of
adding more code complexity.
In addition, simplifying the code will allow you to use the timer-of
code and reduce very significantly the init function.
That's what I had in my V1 and V2, my DT node for the timer-ingenic
driver
had a "timers" property (e.g. "timers = <4 5>;") to select the
channels
that
should be used as timers. Then Rob told me I shouldn't do that, and
instead
detect the channels that will be used for PWM.
[ ... ]
How do you specify the channels used for PWM ?
To detect the channels that will be used as PWM I parse the whole
devicetree
searching for "pwms" properties; check that the PWM handle is for our
TCU PWM
driver; then read the PWM number from there.
Of course it's hackish, and it only works for devicetree. I preferred
the
method with the "timers" property.
+config INGENIC_TIMER
+ bool "Clocksource/timer using the TCU in Ingenic JZ SoCs"
+ depends on MACH_INGENIC || COMPILE_TEST
bool "Clocksource/timer using the TCU in Ingenic JZ SoCs" if
COMPILE_TEST
Remove the depends MACH_INGENIC.
This driver is not useful on anything else than Ingenic SoCs, why
should I
remove MACH_INGENIC then?
For COMPILE_TEST on x86.
Well that's a logical OR right here, so it will work...
Right, I missed the second part of the condition. For consistency
reason, we don't add a dependency on the platform. The platform will
select it. Look the other timer options and you will see there is no
MACH deps. I'm trying consolidating all these options to have same
format and hopefully factor them out.
I'm all for factorisation, but what I dislike with not depending on
MACH_INGENIC, is that the driver now appears in the menuconfig for
every arch, even if it only applies to one MIPS SoC.
Regards,
-Paul
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