On 03/04/2014 03:04 AM, Thomas Gleixner wrote: > On Mon, 3 Mar 2014, Stephen Warren wrote: > >> From: Stephen Warren <swarren@xxxxxxxxxx> >> >> Some devices have configurable IRQ output polarities. Software might >> use IRQ_TYPE_* to determine how to configure such a device's IRQ >> output polarity in order to match how the IRQ controller input is >> configured. If the board or SoC inverts the signal between the >> device's IRQ output and controller's IRQ output, software must be >> aware of this fact, in order to program the IRQ output to the correct >> (i.e. opposite) polarity. This flag provides that information. > > So what you're saying is: > > Device IRQ output --> [Optional Inverter Logic] --> IRQ controller input. > > And you're storing the information about the presence of the inverter > logic in the irq itself, but the core does not make any use of it and > you let the device driver deal with the outcome. > > This sucks as all affected drivers have to implement the same sanity > logic for this. > > Why don't you implement a core function which tells the driver which > polarity to select? That requires a few more changes, but I think it's > worth it for other reasons. > > Right now the set_type logic requires the irq chip drivers to > implement sanity checking and default selections for TYPE_NONE. We can > be more clever about that and add this information to the irq chip > flags. I don't see any such checking in drivers/irqchip/irq-gic.c; it rejects any type other than IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_EDGE_RISING, and I don't see any mention of TYPE_NONE in that file. Is the driver incomplete? Instead of adding all this extra logic to the core, what do you think of simply telling each driver that has a configurable interrupt output polarity exactly which polarity to use. This information would come from device tree or platform data. This is what I implemented in V1/V2 of this series: http://www.spinics.net/lists/devicetree/msg23648.html Is that any better, or do you definitely want the IRQ core to manage this? -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
