Messages in this thread | | | Date | Tue, 4 Mar 2014 11:34:13 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH V3 1/5] genirq: define flag IRQ_SRC_DST_INVERTED, and accessors |
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On Tue, 4 Mar 2014, Thomas Gleixner wrote:
> On Mon, 3 Mar 2014, Stephen Warren wrote: > > > From: Stephen Warren <swarren@nvidia.com> > > > > 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. > > enum { > IRQ_CHIP_TYPES_MASK = 0x0f, > IRQ_CHIP_DEFAULT_MASK = 0xf0, > IRQ_CHIP_EXISTING_FLAGS .... > }
We need to extend the mask to indicate whether the chip supports BOTH_EDGES. A chip can support FALLING and RISING, but not both at the same time. For the set_type side the current BOTH = FALLING | RISING is fine, but for checking the supported type it's not sufficient.
Thanks,
tglx
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