soundwire: cadence: recheck device0 attachment after status change - #3442
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This patch adds a status check after device0 attachment to solve race conditions observed during attachment with multiple devices per link The sequence is the following 1) deviceA attaches as device0 2) the hardware detects a device0 status change and throws an interrupt. 3) the interrupt handler schedules the work function 4) the workqueue starts, we read the status slave0 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT0); slave1 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT1); we deal with the status change and program deviceA device number to a non-zero value. 5) deviceB attaches as device0, the device0 status seen by the hardware does not change. 6) we clear the CDNS_MCP_SLAVE_INTSTAT0/1 registers -> we will never detect deviceB! This patch suggest re-checking in a loop the device0 status with a PING frame, i.e. using the real device0 status instead of information on status changes. Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
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Is this related to some existing bug(s) already filed? If yes then the links would be useful IMHO. |
yeah, forgot to add |
bardliao
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bardliao
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LGTM, let's see will this patch fix the issue.
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Why once the device is unattached , it will never be attached again ? |
thats' the point, it may reattach but if it does so before we clear the interrupt status bits we will never detect it. |
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ok, let's merge this and see if this changes the behavior on Volteer+TGL RVP. @bardliao let's wait to upstream this for now, we need at least a couple of weeks of test results. |
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This patch adds a status check after device0 attachment to solve race
conditions observed during attachment with multiple devices per link
The sequence is the following
deviceA attaches as device0
the hardware detects a device0 status change and throws an
interrupt.
the interrupt handler schedules the work function
the workqueue starts, we read the status
slave0 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT0);
slave1 = cdns_readl(cdns, CDNS_MCP_SLAVE_INTSTAT1);
we deal with the status change and program deviceA device number to a
non-zero value.
deviceB attaches as device0, the device0 status seen by the
hardware does not change.
we clear the CDNS_MCP_SLAVE_INTSTAT0/1 registers -> we will never detect
deviceB!
This patch suggest re-checking in a loop the device0 status with a
PING frame, i.e. using the real device0 status instead of information
on status changes.
Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com