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[TEST] soundwire: bus: clear bus clash interrupt after attached #2582

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Merged
plbossart merged 2 commits into from
Dec 2, 2020
Merged

[TEST] soundwire: bus: clear bus clash interrupt after attached #2582

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soundwire: bus: clear bus clash interrupt before the mask is enabled
bardliao Nov 25, 2020
7a2abd8
soundwire: intel: add SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH quirk
bardliao Dec 1, 2020
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10 changes: 10 additions & 0 deletions drivers/soundwire/bus.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1257,13 +1257,23 @@ static int sdw_slave_set_frequency(struct sdw_slave *slave)
static int sdw_initialize_slave(struct sdw_slave *slave)
{
struct sdw_slave_prop *prop = &slave->prop;
int status;
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@plbossart plbossart Dec 1, 2020

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Commit message:

The SoundWire specification allows a Slave device to report a bus clash with the in-band interrupt mechanism when it detects a conflict while driving a bitSlot it owns. This can be a symptom of an electrical conflict or a programming error, and it's vital to detect reliably.

Unfortunately, on some platforms, bus clashes are randomly reported by Slave devices after a bus reset, with an interrupt status set even before the bus clash interrupt is enabled. These initial spurious interrupts are not relevant and should optionally be filtered out, while leaving the interrupt mechanism enabled to detect 'true' issues.

This patch suggests the addition of a Master level quirk to discard such interrupts. The quirk should in theory have been added at the Slave level, but since the problem was detected with different generations of Slave devices it's hard to point to a specific IP. The problem might also be board-dependent and hence dealing with a Master quirk is simpler.

int ret;
u8 val;

ret = sdw_slave_set_frequency(slave);
if (ret < 0)
return ret;

if (slave->bus->prop.quirks & SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH) {
/* Clear bus clash interrupt before enabling interrupt mask */
status = sdw_read_no_pm(slave, SDW_SCP_INT1);
if (status & SDW_SCP_INT1_BUS_CLASH) {
dev_warn(&slave->dev, "Bus clash detected before INT mask is enabled\n");
sdw_write_no_pm(slave, SDW_SCP_INT1, SDW_SCP_INT1_BUS_CLASH);
}
}

/*
* Set SCP_INT1_MASK register, typically bus clash and
* implementation-defined interrupt mask. The Parity detection
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2 changes: 2 additions & 0 deletions drivers/soundwire/intel.c
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Expand Up @@ -1286,6 +1286,8 @@ static int sdw_master_read_intel_prop(struct sdw_bus *bus)
if (quirk_mask & SDW_INTEL_QUIRK_MASK_BUS_DISABLE)
prop->hw_disabled = true;

prop->quirks = SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH;

return 0;
}

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4 changes: 4 additions & 0 deletions include/linux/soundwire/sdw.h
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Expand Up @@ -405,6 +405,7 @@ struct sdw_slave_prop {
* command
* @mclk_freq: clock reference passed to SoundWire Master, in Hz.
* @hw_disabled: if true, the Master is not functional, typically due to pin-mux
* @quirks: bitmask identifying optional behavior beyond the scope of the MIPI specification
*/
struct sdw_master_prop {
u32 revision;
Expand All @@ -421,8 +422,11 @@ struct sdw_master_prop {
u32 err_threshold;
u32 mclk_freq;
bool hw_disabled;
u32 quirks;
};

#define SDW_MASTER_QUIRKS_CLEAR_INITIAL_CLASH BIT(0)

int sdw_master_read_prop(struct sdw_bus *bus);
int sdw_slave_read_prop(struct sdw_slave *slave);

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