[RFC PATCH v4 3/3] PM / clock_ops: add and enable clocks always if !CONFIG_PM_RUNTIME

Grygorii Strashko grygorii.strashko at ti.com
Thu Nov 6 05:51:02 PST 2014

Device's clocks need to be enabled always at probing time
if !CONFIG_PM_RUNTIME - in that way, device will become accesible
and, later, its clocks can be disabled/enabled during system
suspend/resume by using pm_clk_suspend/pm_clk_resume APIs.

But now, the clocks management code doesn't enable clocks when
clocks are being registered per-device by using pm_clk_add/_clk().
So, update pm_clk_acquire(), which is called from pm_clk_add/_clk(),
to enable clock always if !CONFIG_PM_RUNTIME.

Also, Platform PM domains drivers will not have to add code like below
each time they need to handle the case when !CONFIG_PM_RUNTIME [1 - 3]:

               ret = pm_clk_resume(dev);
               if (ret) {
                       dev_err(dev, "pm_clk_resume failed %d\n", ret);
                       goto clk_err;

[1] https://lkml.org/lkml/2014/10/3/306
[2] https://lkml.org/lkml/2014/10/16/305
[3] https://lkml.org/lkml/2014/10/20/249

CC: Santosh Shilimkar <ssantosh at kernel.org>
CC: Kevin Hilman <khilman at linaro.org>
CC: Ulf Hansson <ulf.hansson at linaro.org>
CC: Geert Uytterhoeven <geert at linux-m68k.org>
CC: Dmitry Torokhov <dmitry.torokhov at gmail.com>
CC: Philipp Zabel <p.zabel at pengutronix.de>
CC: Caesar Wang <caesar.wang at rock-chips.com>

Signed-off-by: Grygorii Strashko <grygorii.strashko at ti.com>

I marked it as RFC, because:
  Generic clock manipulation PM callbacks can be used for any device
  for which list of clocks need to be maintained - and it doesn't mean
  that this framework need to be always connected to GPD/Runtime PM or
  used during suspend resume. Also, for DT-use case - it doesn't perform
  any actions (except clk_prepare) on clocks by itself and only
  by request from framework's consumer.

 For example, it can be reused by Power domain/controller drivers like:
 - Rockchip RK3288 PM Domain (https://lkml.org/lkml/2014/11/6/30)
 - IMX.6 PU power domain (http://www.spinics.net/lists/arm-kernel/msg360709.html)

 to maintain list of clocks for GPD itself and these clocks should not
 be enabled by default, because they are used to power on/off Power domain
 in a specific way:
     - enable all clocks assigned to PD
     - power on/off PD
     - disable all clocks assigned to PD.
 After this patch it will be impossible to reuse Generic clock manipulation PM
 callbacks in cases described above.

 drivers/base/power/clock_ops.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/base/power/clock_ops.c b/drivers/base/power/clock_ops.c
index b32b5d4..36cdff7 100644
--- a/drivers/base/power/clock_ops.c
+++ b/drivers/base/power/clock_ops.c
@@ -69,6 +69,10 @@ static void pm_clk_acquire(struct device *dev, struct pm_clock_entry *ce)
 		ce->status = PCE_STATUS_ACQUIRED;
 		dev_dbg(dev, "Clock %s managed by runtime PM.\n", ce->con_id);
+		__pm_clk_enable(dev, ce);
+	}
 static int __pm_clk_add(struct device *dev, const char *con_id,

More information about the linux-arm-kernel mailing list