Mathieu Poirier <mathieu.poirier@xxxxxxxxxx> writes:
> On 3 November 2014 08:34, Geert Uytterhoeven <geert+renesas@xxxxxxxxx> wrote:
>> Hi Rafael, Simon, Magnus,
>>
>> This patch series enables DT support for PM domains on Renesas R-Mobile SoCs.
>>
>> Currently it's limited to R-Mobile A1 (r8a7740), but given the similarity of
>> the SYSC System-Controller on the various SH-Mobile/R-Mobile SoCs, and the
>> abstraction of PM domains in DT, it should be sufficiently generic to handle
>> other SoCs in the future (e.g. SH-Mobile AP4 (sh7372), SH-Mobile AG5 (sh73a0),
>> R-Mobile APE6 (r8a73a4)).
>>
>> Functionality-wise, this behaves the same as the legacy (non-DT) version
>> (modulo missing DT support in some device drivers).
>>
>> Dependencies:
>> - This is based on Simon Horman's renesas-devel-20141030-v3.18-rc2, and
>> Rafael J. Wysocki's linux-pm.git#linux-next,
>> - This depends on "PM / Domains: Change prototype for the ->attach_dev()
>> callback" from Ulf hanson, which is intended to still enter v3.18-rcX
>> through the linux-pm tree.
>> As this is a one-line change, I included this patch as the first patch of
>> this series. Perhaps it's even acceptable for Simon to (also) apply it, so
>> we don't have to wait for the v3.18-rcX that will include it?
>>
>> For your convenience, I've also pushed this to
>> git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers.git#rmobile-genpd
>>
>> Changes compared to v3 (more detailed changelogs in the individual patches):
>> - I dropped the patch to add preliminary PM domain latencies, as I want to do
>> more measurements for PM domains that are currently never powered off.
>> Values seem to range between 8.5 and 26 us, depending on the PM domain.
>> - I dropped all patches related to QoS device latencies, as these need more
>> discussion,
>> - The power-{on,off}-latency properties have been changed from a single value
>> to a list,
>> - Device save/restore state latencies have been dropped, as they're Linux
>> driver-specific, and thus don't belong in DT,
>> - Use proper pm_clk_create()/pm_clk_destroy(), and update for attach_dev()
>> returning an error code again,
>> - New patch to enable module clocks if !CONFIG_PM_RUNTIME,
>> - Always keep D4 powered, until the new Coresight code handles runtime
>> PM,
>
> I took the time to really look at the problems you are experiencing
> with pm runtime in hw_breackpoint.c this weekend. The coresight
> patchset, when supplemented with PM runtime awareness, will fix that
> problem *only* when traces are activated. The other obvious condition
> is that other component using the same power domain are also converted
> to using runtime PM.
>
> That being said, the coresight framework and breakpoint handler code
> are two different subsystem. Their only commonality is that they make
> use of the debug registers (and not even the same ones). As such (and
> in my opinion) the code in hw_breakpoint should be getting its own pm
> runtime reference without relying on the coresight subsystem. As
> indicated above, that would only work in some cases.
>
> Supplementing hw_breakpoint to interact with the runtime PM may prove
> trickier than it seems... I'm especially worried about the
> non-blocking requirement inherent to using "smp_call_function()". I'm
> stepping forward to look into that problem but before doing so I need
> to finish runtime PM on coresight.
Matthieu, without looking more deeply myself, I'm not sure this is what
you need, but have a look at the "IRQ safe" mode of runtime PM. If you
know your devices runtime PM callbacks are IRQ safe, you can call
pm_runtime_irq_safe(), and your callbacks will be called with IRQs
disabled.
Kevin
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