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    Subject[PATCH 5.10 254/717] soundwire: master: use pm_runtime_set_active() on add
    Date
    From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

    [ Upstream commit e04e60fce47e61743a8726d76b0149c1f4ad8957 ]

    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    master device will suspend when all its children are no longer active.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>
    Link: https://lore.kernel.org/r/20201124130742.10986-1-yung-chuan.liao@linux.intel.com
    Signed-off-by: Vinod Koul <vkoul@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/soundwire/master.c | 14 ++++++++++++++
    1 file changed, 14 insertions(+)

    diff --git a/drivers/soundwire/master.c b/drivers/soundwire/master.c
    index 3488bb824e845..9b05c9e25ebe4 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);
    device_register_err:
    return ret;
    }
    --
    2.27.0


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