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| author | Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> | 2020-11-24 09:33:14 +0800 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2020-11-25 10:32:25 +0530 |
| commit | 6e06a85556f9725865af91c9fe502c9669518ed5 (patch) | |
| tree | f10e067ea1bc03c8d6860b559cb4d73259297f12 /drivers/soundwire | |
| parent | b7cab9be7c16128a0de21ed7ae67211838813437 (diff) | |
| download | linux-6e06a85556f9725865af91c9fe502c9669518ed5.tar.gz linux-6e06a85556f9725865af91c9fe502c9669518ed5.tar.bz2 linux-6e06a85556f9725865af91c9fe502c9669518ed5.zip | |
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.c | 7 |
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]; |