Message-ID: <CANLsYkzVw_fQQuK9pEomMp6A_z2Qg9L-Hj1f+8b_1o7cFjMiDw@mail.gmail.com>
Date:	Mon, 3 Nov 2014 14:02:31 -0700
From:	Mathieu Poirier <mathieu.poirier@...aro.org>
To:	Geert Uytterhoeven <geert+renesas@...der.be>
Cc:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Simon Horman <horms@...ge.net.au>,
	Magnus Damm <magnus.damm@...il.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Kevin Hilman <khilman@...aro.org>,
	Grygorii Strashko <grygorii.strashko@...com>,
	Philipp Zabel <philipp.zabel@...il.com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	linux-pm@...r.kernel.org,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v4 0/9] ARM: shmobile: R-Mobile: DT PM domain support

On 3 November 2014 08:34, Geert Uytterhoeven <geert+renesas@...der.be> 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.


>   - Remove bogus power-domains properties from clock nodes, as these will not
>     be instantiated as platform devices,
>   - Add power-domains properties to the recently added TMU nodes,
>   - Added Acked-by, Reviewed-by.
>
> Changes compared to v2 (more detailed changelogs in the individual patches):
>   - Minor changes to attach/detach callbacks,
>   - Really add the A4MP and D4 PM domains, as fixes are available (see
>     dependencies below),
>   - Scan DT topology to identify special PM domains (CPUs and console),
>   - Move PM domain power-on/off latencies to a separate patch.
>
> Changes compared to v1 (more detailed changelogs in the individual patches):
>   - Several new patches: PM QoS device latencies in DT, attach/detach
>     callbacks,
>   - Run-Time management of the module clocks, making the hack in
>     drivers/sh/pm_runtime.c obsolete for DT platforms using genpd,
>   - Addition of PM QoS device latencies, specified from DT,
>   - Addition of build glue, so this builds and runs without additional
>     changes, incl. s2ram.
>
> Thanks!
>
> Geert Uytterhoeven (8):
>   PM / Domains: Add DT bindings for power-on/off latencies
>   PM / Domains: Add DT bindings for the R-Mobile System Controller
>   ARM: shmobile: R-Mobile: Use generic_pm_domain.attach_dev() for pm_clk
>     setup
>   ARM: shmobile: R-Mobile: Enable module clocks if !CONFIG_PM_RUNTIME
>   ARM: shmobile: R-Mobile: Store SYSC base address in rmobile_pm_domain
>   ARM: shmobile: R-Mobile: Add DT support for PM domains
>   ARM: shmobile: r8a7740 dtsi: Add PM domain support
>   drivers: sh: Disable PM runtime for multi-platform r8a7740 with genpd
>
> Ulf Hansson (1):
>   PM / Domains: Change prototype for the ->attach_dev() callback
>
>  .../devicetree/bindings/power/power_domain.txt     |  14 +-
>  .../bindings/power/renesas,sysc-rmobile.txt        | 107 ++++++++
>  arch/arm/boot/dts/r8a7740.dtsi                     |  99 +++++++
>  arch/arm/mach-shmobile/Kconfig                     |   3 +-
>  arch/arm/mach-shmobile/pm-r8a7740.c                |  14 +
>  arch/arm/mach-shmobile/pm-rmobile.c                | 284 +++++++++++++++++++--
>  arch/arm/mach-shmobile/pm-rmobile.h                |   3 +-
>  arch/arm/mach-shmobile/pm-sh7372.c                 |  11 +
>  drivers/sh/pm_runtime.c                            |   2 +
>  include/linux/pm_domain.h                          |   2 +-
>  10 files changed, 519 insertions(+), 20 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/power/renesas,sysc-rmobile.txt
>
> --
> 1.9.1
>
> Gr{oetje,eeting}s,
>
>                                                 Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                                             -- Linus Torvalds
> --
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