Intel QA reported a very rare case, possibly hardware-dependent, where a Slave can become UNATTACHED during a clock stop sequence, which leads to timeouts and failed suspend sequences. This patch suppresses the handling of all Slave events while this transition happens. The two cases that matter are: a) alerts: if the Slave wants to signal an alert condition, it can do so using the in-band wake, so there's almost no impact with this patch. b) sync loss or imp-def reset: in those cases, bringing back the Slave to functional state requires a complete re-enumeration. It's better to just ignore this case and restart cleanly, rather than attempt a 'clean' suspend. Validation results show the timeouts no longer visible with this patch. GitHub issue: https://github.com/thesofproject/linux/issues/1678 Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx> --- drivers/soundwire/cadence_master.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/drivers/soundwire/cadence_master.c b/drivers/soundwire/cadence_master.c index 02f18ce6b7e7..a4ba57f44c1f 100644 --- a/drivers/soundwire/cadence_master.c +++ b/drivers/soundwire/cadence_master.c @@ -865,6 +865,24 @@ int sdw_cdns_exit_reset(struct sdw_cdns *cdns) } EXPORT_SYMBOL(sdw_cdns_exit_reset); +/** + * sdw_cdns_enable_slave_interrupt() - Enable SDW slave interrupts + * @cdns: Cadence instance + * @state: boolean for true/false + */ +static void cdns_enable_slave_interrupts(struct sdw_cdns *cdns, bool state) +{ + u32 mask; + + mask = cdns_readl(cdns, CDNS_MCP_INTMASK); + if (state) + mask |= CDNS_MCP_INT_SLAVE_MASK; + else + mask &= ~CDNS_MCP_INT_SLAVE_MASK; + + cdns_writel(cdns, CDNS_MCP_INTMASK, mask); +} + /** * sdw_cdns_enable_interrupt() - Enable SDW interrupts * @cdns: Cadence instance @@ -1272,6 +1290,13 @@ int sdw_cdns_clock_stop(struct sdw_cdns *cdns, bool block_wake) return 1; } + /* + * Before entering clock stop we mask the Slave + * interrupts. This helps avoid having to deal with e.g. a + * Slave becoming UNATTACHED while the clock is being stopped + */ + cdns_enable_slave_interrupts(cdns, false); + /* * For specific platforms, it is required to be able to put * master into a state in which it ignores wake-up trials @@ -1349,6 +1374,9 @@ int sdw_cdns_clock_restart(struct sdw_cdns *cdns, bool bus_reset) { int ret; + /* unmask Slave interrupts that were masked when stopping the clock */ + cdns_enable_slave_interrupts(cdns, true); + ret = cdns_clear_bit(cdns, CDNS_MCP_CONTROL, CDNS_MCP_CONTROL_CLK_STOP_CLR); if (ret < 0) { -- 2.20.1
