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authorPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>2020-11-24 09:33:14 +0800
committerVinod Koul <vkoul@kernel.org>2020-11-25 10:32:25 +0530
commit6e06a85556f9725865af91c9fe502c9669518ed5 (patch)
treef10e067ea1bc03c8d6860b559cb4d73259297f12 /drivers/soundwire
parentb7cab9be7c16128a0de21ed7ae67211838813437 (diff)
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soundwire: bus: add comments to explain interrupt loop filter
The interrupt handling in SoundWire requires software to re-read the interrupt status after clearing an interrupt. In case the interrupt is still outstanding, the code in bus.c will loop a number of times, however that loop is limited to the interrupts detected in the first read. This strategy helps meet SoundWire requirements without remaining forever in an interrupt handler. Add a couple of comments to document this design. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> Reviewed-by: Guennadi Liakhovetski <guennadi.liakhovetski@linux.intel.com> Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com> Link: https://lore.kernel.org/r/20201124013318.8963-2-yung-chuan.liao@linux.intel.com Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/soundwire')
-rw-r--r--drivers/soundwire/bus.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index ffe4600fd95b..45131b9f5080 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1334,6 +1334,7 @@ static int sdw_handle_dp0_interrupt(struct sdw_slave *slave, u8 *slave_status)
"SDW_DP0_INT read failed:%d\n", status2);
return status2;
}
+ /* filter to limit loop to interrupts identified in the first status read */
status &= status2;
count++;
@@ -1404,6 +1405,7 @@ static int sdw_handle_port_interrupt(struct sdw_slave *slave,
"SDW_DPN_INT read failed:%d\n", status2);
return status2;
}
+ /* filter to limit loop to interrupts identified in the first status read */
status &= status2;
count++;
@@ -1589,7 +1591,10 @@ static int sdw_handle_slave_alerts(struct sdw_slave *slave)
sdca_cascade = ret & SDW_DP0_SDCA_CASCADE;
}
- /* Make sure no interrupts are pending */
+ /*
+ * Make sure no interrupts are pending, but filter to limit loop
+ * to interrupts identified in the first status read
+ */
buf &= _buf;
buf2[0] &= _buf2[0];
buf2[1] &= _buf2[1];