soundwire: bus: add helper to clear Slave status to UNATTACHED (3ab2ca40) · Commits · 戴 / test

When resuming with a bus reset, we need to re-enumerate and restart from UNATTACHED. The helper added in this patch helps implement a more robust state machine avoiding race conditions on resume. The unattach request is stored and will be used by Slave drivers, if needed: Intel validation exposed a corner case where the Slave device may transition to D3 when streaming stops, but streaming restarts before the Master transitions to D3. In that case, the Slave status was not cleared as UNATTACHED by the Master resuming, and the wait_for_completion will time out. When the slave resumes, it can check if a Master-initiated re-enumeration and initialization took place and skip the wait_for_completion() if there is no reason to wait. Signed-off-by:

Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Link: https://lore.kernel.org/r/20200115000844.14695-7-pierre-louis.bossart@linux.intel.com Signed-off-by:

Vinod Koul <vkoul@kernel.org>

drivers/soundwire/bus.c

+27 −0

Original line number	Diff line number	Diff line
		@@ -1163,3 +1163,30 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
		return ret;
		}
		EXPORT_SYMBOL(sdw_handle_slave_status);

		void sdw_clear_slave_status(struct sdw_bus *bus, u32 request)
		{
		struct sdw_slave *slave;
		int i;

		/* Check all non-zero devices */
		for (i = 1; i <= SDW_MAX_DEVICES; i++) {
		mutex_lock(&bus->bus_lock);
		if (test_bit(i, bus->assigned) == false) {
		mutex_unlock(&bus->bus_lock);
		continue;
		}
		mutex_unlock(&bus->bus_lock);

		slave = sdw_get_slave(bus, i);
		if (!slave)
		continue;

		if (slave->status != SDW_SLAVE_UNATTACHED)
		sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);

		/* keep track of request, used in pm_runtime resume */
		slave->unattach_request = request;
		}
		}
		EXPORT_SYMBOL(sdw_clear_slave_status);

drivers/soundwire/bus.h

+8 −0

Original line number	Diff line number	Diff line
		@@ -165,4 +165,12 @@ sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
		return sdw_write(slave, addr, tmp);
		}

		/*
		* At the moment we only track Master-initiated hw_reset.
		* Additional fields can be added as needed
		*/
		#define SDW_UNATTACH_REQUEST_MASTER_RESET BIT(0)

		void sdw_clear_slave_status(struct sdw_bus *bus, u32 request);

		#endif /* __SDW_BUS_H */

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