-----Original Message----- From: Vinod Koul vkoul@kernel.org Sent: Wednesday, November 25, 2020 1:05 PM To: Bard Liao yung-chuan.liao@linux.intel.com Cc: alsa-devel@alsa-project.org; linux-kernel@vger.kernel.org; gregkh@linuxfoundation.org; jank@cadence.com; srinivas.kandagatla@linaro.org; rander.wang@linux.intel.com; ranjani.sridharan@linux.intel.com; hui.wang@canonical.com; pierre- louis.bossart@linux.intel.com; Kale, Sanyog R sanyog.r.kale@intel.com; Lin, Mengdong mengdong.lin@intel.com; Liao, Bard bard.liao@intel.com Subject: Re: [PATCH] soundwire: master: use pm_runtime_set_active() on add
On 24-11-20, 21:07, Bard Liao wrote:
From: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com
The 'master' device acts as a glue layer used during bus initialization only, and it needs to be 'transparent' for pm_runtime management. Its behavior should be that it becomes active when one of its children becomes active, and suspends when all of its children are suspended.
In our tests on Intel platforms, we routinely see these sort of warnings on the initial boot:
[ 21.447345] rt715 sdw:3:25d:715:0: runtime PM trying to activate child device sdw:3:25d:715:0 but parent (sdw-master-3) is not active
This is root-caused to a missing setup to make the device 'active' on probe. Since we don't want the device to remain active forever after the probe, the autosuspend configuration is also enabled at the end of the probe - the device will actually autosuspend only in the case where there are no devices physically attached. In practice, the master device will suspend when all its children are no longer active.
Fixes: bd84256e86ecf ('soundwire: master: enable pm runtime') Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Reviewed-by: Rander Wang rander.wang@linux.intel.com Signed-off-by: Bard Liao yung-chuan.liao@linux.intel.com
drivers/soundwire/master.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)
diff --git a/drivers/soundwire/master.c b/drivers/soundwire/master.c index 3488bb824e84..9b05c9e25ebe 100644 --- a/drivers/soundwire/master.c +++ b/drivers/soundwire/master.c @@ -8,6 +8,15 @@ #include <linux/soundwire/sdw_type.h> #include "bus.h"
+/*
- The 3s value for autosuspend will only be used if there are no
- devices physically attached on a bus segment. In practice enabling
- the bus operation will result in children devices become active
+and
- the master device will only suspend when all its children are no
- longer active.
- */
+#define SDW_MASTER_SUSPEND_DELAY_MS 3000
/*
- The sysfs for properties reflects the MIPI description as given
- in the MIPI DisCo spec
@@ -154,7 +163,12 @@ int sdw_master_device_add(struct sdw_bus *bus,
struct device *parent,
bus->dev = &md->dev; bus->md = md;
- pm_runtime_set_autosuspend_delay(&bus->md->dev,
SDW_MASTER_SUSPEND_DELAY_MS);
- pm_runtime_use_autosuspend(&bus->md->dev);
- pm_runtime_mark_last_busy(&bus->md->dev);
- pm_runtime_set_active(&bus->md->dev); pm_runtime_enable(&bus->md->dev);
- pm_runtime_idle(&bus->md->dev);
I understand that this needs to be done somewhere but is the core the right place. In intel case it maybe a dummy device but other controllers are real devices and may not support pm.
I think better idea would be to do this in respective driver.. that way it would be an opt-in for device supporting pm.
Should it be put in the same place as pm_runtime_enable? IMHO, pm_runtime_enable is in the core already and it seems to be harmless for devices which don't support pm. And pm can still be optional on md's parent device.
Thanks
~Vinod