On 2017-01-17 09:00, Phil Reid wrote: > Unfortunately some hardware device will assert their irq line immediately > on power on and provide no mechanism to mask the irq. As the i2c muxes > provide no method to mask irq line this provides a work around by keeping > the parent irq masked until enough device drivers have loaded to service > all pending interrupts. > > For example the the ltc1760 assert its SMBALERT irq immediately on power > on. With two ltc1760 attached to bus 0 & 1 on a pca954x mux when the first > device is registered irq are enabled and fire continuously as the second > device driver has not yet loaded. Setting this parameter to <1 1> will > delay the irq being enabled until both devices are ready. Hang on, does this suggestion I made make any sense at all? Maybe it does, but does the pca954x driver even get notified of any but the first irq client that unmasks interrupts on a mux segment? How can it count the number of active irq clients if not? I'm truly sorry for the trouble I'm causing by not just saying how it should be done from the start, but I feel like I've been thrown in at the deep end when it comes to interrupt controllers... Cheers, peda > Signed-off-by: Phil Reid <preid@xxxxxxxxxxxxxxxxx> > --- > Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt > index aa09704..ac71be6 100644 > --- a/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt > +++ b/Documentation/devicetree/bindings/i2c/i2c-mux-pca954x.txt > @@ -19,6 +19,8 @@ Optional Properties: > - i2c-mux-idle-disconnect: Boolean; if defined, forces mux to disconnect all > children in idle state. This is necessary for example, if there are several > multiplexers on the bus and the devices behind them use same I2C addresses. > + - nxp,irq-mask-enable: array; Defines the minimum number of chips that must > + register an irq for each channel before the parent irq line in enabled. > - interrupt-parent: Phandle for the interrupt controller that services > interrupts for this device. > - interrupts: Interrupt mapping for IRQ. > @@ -36,6 +38,7 @@ Example: > #size-cells = <0>; > reg = <0x74>; > > + nxp,irq-mask-enable = <0 0 0 0 1 0 0 0>; > interrupt-parent = <&ipic>; > interrupts = <17 IRQ_TYPE_LEVEL_LOW>; > interrupt-controller; > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
