mcp2515: Change interrupt to TRIGGER_LOW #2267
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This was referenced Nov 14, 2017
msperl
reviewed
Nov 14, 2017
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Thanks. I've reworked it to simply zero the flags if the device has a DT node. |
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you could also change the DT to: But I am not sure if this would really work with the overlays the way these are built... |
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I considered that, and it does work, but people often build the overlays outside the kernel tree and I didn't want to add an unnecessary external dependency. I will change the comment to IRQ_TYPE_* though. |
The MCP2515 datasheet clearly describes a level-triggered interrupt pin. Therefore the receiving interrupt controller must also be configured for level-triggered operation otherwise there is a danger of a missed interrupt condition blocking all subsequent interrupts. The ONESHOT flag ensures that the interrupt is masked until the threaded interrupt handler exits. Rather than change the flags globally (they must have worked for at least one user), allow the flags to be overridden from Device Tree in the event that the device has a DT node. See: raspberrypi#2175 raspberrypi#2263 Signed-off-by: Phil Elwell <[email protected]>
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[ If this is effective we should reconsider all usage of edge-triggered interrupts. ]
The MCP2515 datasheet clearly describes a level-triggered interrupt
pin. Therefore the receiving interrupt controller must also be
configured for level-triggered operation otherwise there is a danger
of a missed interrupt condition blocking all subsequent interrupts.
The ONESHOT flag ensures that the interrupt is masked until the
threaded interrupt handler exits.
See: #2175
#2263
Signed-off-by: Phil Elwell [email protected]