Hi Stephen, > There were some comments about adding an 'optional' platform_get_irq() > API in v4. This series doesn't include that, but I can add such an API > if it's required. I started to look into how it might work and got hung > up on what an optional IRQ means. I suppose it means that in DT there > isn't an 'interrupts' property in the device node, but in ACPI based > firmware I'm not sure what that would correspond to. Furthermore, the > return value is hard to comprehend. Do we return an error when an > optional irq can't be found? It doesn't seem safe to return 0 because > sometimes 0 is a valid IRQ. Do other errors in parsing the IRQ > constitute a failure when the IRQ is optional?
Some time ago, I tried a series like yours and got stuck at this very point. I found drivers where using an interrupt was optional and platform_get_irq() returning a failure wasn't fatal. The drivers used PIO then or dropped some additional functionality. Some of them were very old. I didn't like the idea that platform_get_irq() will spit out errors for those drivers, yet I couldn't create a suitable cocci-script to convert drivers to use the *_optional callback where possible. So, I neither created the optional callback. I still have doubts of unneeded error messages popping up. Has this been discussed already? (Sorry, I missed the first iterations of this series) Thanks, Wolfram
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