soundwire: intel: pm_runtime idle scheduling

Add quirk and pm_runtime idle scheduling to let the Master suspend if
no Slaves become attached. This can happen when a link is not marked
as disabled and has devices exposed in the DSDT, if the power is
controlled by sideband means or the link includes a pluggable
connector.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-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/20200817152923.3259-7-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index 95a1d88a5bfbf734f736851daab1d4f20965996e..3f9015dcb693d32417f5228c5cca2bea9be76d41 100644 (file)
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -31,8 +31,9 @@
  * flags reused in each byte, with master0 using the ls-byte, etc.
  */
 
-#define SDW_INTEL_MASTER_DISABLE_PM_RUNTIME BIT(0)
-#define SDW_INTEL_MASTER_DISABLE_CLOCK_STOP BIT(1)
+#define SDW_INTEL_MASTER_DISABLE_PM_RUNTIME            BIT(0)
+#define SDW_INTEL_MASTER_DISABLE_CLOCK_STOP            BIT(1)
+#define SDW_INTEL_MASTER_DISABLE_PM_RUNTIME_IDLE       BIT(2)
 
 static int md_flags;
 module_param_named(sdw_md_flags, md_flags, int, 0444);
@@ -1422,6 +1423,22 @@ int intel_master_startup(struct platform_device *pdev)
                pm_runtime_enable(dev);
        }
 
+       /*
+        * The runtime PM status of Slave devices is "Unsupported"
+        * until they report as ATTACHED. If they don't, e.g. because
+        * there are no Slave devices populated or if the power-on is
+        * delayed or dependent on a power switch, the Master will
+        * remain active and prevent its parent from suspending.
+        *
+        * Conditionally force the pm_runtime core to re-evaluate the
+        * Master status in the absence of any Slave activity. A quirk
+        * is provided to e.g. deal with Slaves that may be powered on
+        * with a delay. A more complete solution would require the
+        * definition of Master properties.
+        */
+       if (!(link_flags & SDW_INTEL_MASTER_DISABLE_PM_RUNTIME_IDLE))
+               pm_runtime_idle(dev);
+
        return 0;
 
 err_interrupt:
@@ -1561,6 +1578,7 @@ static int intel_resume(struct device *dev)
        struct sdw_cdns *cdns = dev_get_drvdata(dev);
        struct sdw_intel *sdw = cdns_to_intel(cdns);
        struct sdw_bus *bus = &cdns->bus;
+       int link_flags;
        int ret;
 
        if (bus->prop.hw_disabled) {
@@ -1577,6 +1595,10 @@ static int intel_resume(struct device *dev)
                pm_runtime_set_active(dev);
                pm_runtime_mark_last_busy(dev);
                pm_runtime_enable(dev);
+
+               link_flags = md_flags >> (bus->link_id * 8);
+               if (!(link_flags & SDW_INTEL_MASTER_DISABLE_PM_RUNTIME_IDLE))
+                       pm_runtime_idle(dev);
        }
 
        ret = intel_init(sdw);