| Message ID | 1421174781-4340-3-git-send-email-boris.brezillon@free-electrons.com |
|---|---|
| State | Superseded, archived |
| Headers | show |
Boris, On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > Add documentation for the dumb demuxer. > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > --- > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > new file mode 100644 > index 0000000..1c777ef > --- /dev/null > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > @@ -0,0 +1,34 @@ > +* Generic Dumb Interrupt Demultiplexer > + > +This Dumb demultiplixer simply forward all incoming interrupts to its > +enabled/unmasked children. Please forgive the potentially naïve question, but what hardware is this describing? thx, Jason. > + > +Required properties: > +- compatible: Should be "irqchip-dumb-demux". > +- interrupt-controller: Identifies the node as an interrupt controller. > +- interrupts-extended or interrupt-parent and interrupts: Reference the source > + interrupt connected to this dumb demuxer. > +- #interrupt-cells: The number of cells to define the interrupts (should be 1). > + The only cell is the IRQ number. > +- irqs: u32 bitfield specifying the interrupts provided by the demuxer. > + > +Examples: > + /* > + * Dumb demuxer controller > + */ > + dumb_irq1_demux: dumb-irq-demux@1 { > + compatible = "irqchip-dumb-demux"; > + interrupt-controller; > + #interrupt-cells = <1>; > + interrupts-extended = <&aic 1 IRQ_TYPE_LEVEL_HIGH 7>; > + irqs = <0x3f>; > + }; > + > + /* > + * Device connected on this dumb demuxer > + */ > + dma: dma-controller@ffffec00 { > + compatible = "atmel,at91sam9g45-dma"; > + reg = <0xffffec00 0x200>; > + interrupts-extended = <&dumb_irq1_demux 0>; > + }; > -- > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Jason, On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper <jason@lakedaemon.net> wrote: > Boris, > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > > Add documentation for the dumb demuxer. > > > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > > --- > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > > 1 file changed, 34 insertions(+) > > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > new file mode 100644 > > index 0000000..1c777ef > > --- /dev/null > > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > @@ -0,0 +1,34 @@ > > +* Generic Dumb Interrupt Demultiplexer > > + > > +This Dumb demultiplixer simply forward all incoming interrupts to its > > +enabled/unmasked children. > > Please forgive the potentially naïve question, but what hardware is this > describing? That's not a real hardware per se, but on some hardware (like at91 SoCs) some IRQ line are shared by several peripherals, and this dumb demultiplex is here to represent such shared irq lines which cannot be easily demultiplexed (because they do not provide a 'cause' register). You can see it as a virtual irqchip provided to address broken hardware designs. Regards, Boris
Le 13/01/2015 19:46, Boris Brezillon a écrit : > Add documentation for the dumb demuxer. > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com> > --- > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > 1 file changed, 34 insertions(+) > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > new file mode 100644 > index 0000000..1c777ef > --- /dev/null > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > @@ -0,0 +1,34 @@ > +* Generic Dumb Interrupt Demultiplexer > + > +This Dumb demultiplixer simply forward all incoming interrupts to its > +enabled/unmasked children. > + > +Required properties: > +- compatible: Should be "irqchip-dumb-demux". > +- interrupt-controller: Identifies the node as an interrupt controller. > +- interrupts-extended or interrupt-parent and interrupts: Reference the source > + interrupt connected to this dumb demuxer. > +- #interrupt-cells: The number of cells to define the interrupts (should be 1). > + The only cell is the IRQ number. > +- irqs: u32 bitfield specifying the interrupts provided by the demuxer. > + > +Examples: > + /* > + * Dumb demuxer controller > + */ > + dumb_irq1_demux: dumb-irq-demux@1 { > + compatible = "irqchip-dumb-demux"; > + interrupt-controller; > + #interrupt-cells = <1>; > + interrupts-extended = <&aic 1 IRQ_TYPE_LEVEL_HIGH 7>; > + irqs = <0x3f>; > + }; > + > + /* > + * Device connected on this dumb demuxer > + */ > + dma: dma-controller@ffffec00 { > + compatible = "atmel,at91sam9g45-dma"; > + reg = <0xffffec00 0x200>; > + interrupts-extended = <&dumb_irq1_demux 0>; > + }; >
Hey Boris, On Tue, Jan 13, 2015 at 09:52:07PM +0100, Boris Brezillon wrote: > On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper <jason@lakedaemon.net> wrote: > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > > > Add documentation for the dumb demuxer. > > > > > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > > > --- > > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > > > 1 file changed, 34 insertions(+) > > > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > new file mode 100644 > > > index 0000000..1c777ef > > > --- /dev/null > > > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > @@ -0,0 +1,34 @@ > > > +* Generic Dumb Interrupt Demultiplexer > > > + > > > +This Dumb demultiplixer simply forward all incoming interrupts to its > > > +enabled/unmasked children. > > > > Please forgive the potentially naïve question, but what hardware is this > > describing? > > That's not a real hardware per se, but on some hardware (like at91 SoCs) > some IRQ line are shared by several peripherals, and this dumb > demultiplex is here to represent such shared irq lines which cannot be > easily demultiplexed (because they do not provide a 'cause' > register). > > You can see it as a virtual irqchip provided to address broken hardware > designs. Hmm. Well, given tglx's recent reply, I suppose I'll *not* go down the rabbit hole of "the DT is for describing hardware." :-P However, it would probably be a lot more palatable to the DT maintainers if we at least change the compatible to prepend "linux,". This way, if someone does come up with a better solution down the road, it will be much easier to deprecate the binding. I would also be amenable to "virt,", or "hack,", or even "work-around-piss-poor-hw,". Basically, anything that would indicate to consumers of the DT that this is not a true reflection of the hardware, and that it may be superseded by a better solution later. It would also be helpful to explain the situation more fully in the binding document. thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Jason, On Wed, 14 Jan 2015 13:56:19 -0500 Jason Cooper <jason@lakedaemon.net> wrote: > Hey Boris, > > On Tue, Jan 13, 2015 at 09:52:07PM +0100, Boris Brezillon wrote: > > On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper <jason@lakedaemon.net> wrote: > > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > > > > Add documentation for the dumb demuxer. > > > > > > > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > > > > --- > > > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > > > > 1 file changed, 34 insertions(+) > > > > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > new file mode 100644 > > > > index 0000000..1c777ef > > > > --- /dev/null > > > > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > @@ -0,0 +1,34 @@ > > > > +* Generic Dumb Interrupt Demultiplexer > > > > + > > > > +This Dumb demultiplixer simply forward all incoming interrupts to its > > > > +enabled/unmasked children. > > > > > > Please forgive the potentially naïve question, but what hardware is this > > > describing? > > > > That's not a real hardware per se, but on some hardware (like at91 SoCs) > > some IRQ line are shared by several peripherals, and this dumb > > demultiplex is here to represent such shared irq lines which cannot be > > easily demultiplexed (because they do not provide a 'cause' > > register). > > > > You can see it as a virtual irqchip provided to address broken hardware > > designs. > > Hmm. Well, given tglx's recent reply, I suppose I'll *not* go down the > rabbit hole of "the DT is for describing hardware." :-P Actually I'm a bit surprised no one else already mentioned that :-) (I thought this would be the first complain regarding this dumb irq demux chip). Anyway, IMHO, this can be considered as hardware description since these irq-lines are really multiplexed into a single one... > > However, it would probably be a lot more palatable to the DT maintainers > if we at least change the compatible to prepend "linux,". This way, if > someone does come up with a better solution down the road, it will be > much easier to deprecate the binding. > > I would also be amenable to "virt,", or "hack,", or even > "work-around-piss-poor-hw,". Basically, anything that would indicate to > consumers of the DT that this is not a true reflection of the hardware, > and that it may be superseded by a better solution later. Actually I thought about changing it to "virtual,dumb-irq-demux" :-). > > It would also be helpful to explain the situation more fully in the > binding document. Sure, I'll add a few lines to describe what this irqchip really is. Regards, Boris
On Wed, Jan 14, 2015 at 08:08:09PM +0100, Boris Brezillon wrote: > Hi Jason, > > On Wed, 14 Jan 2015 13:56:19 -0500 > Jason Cooper <jason@lakedaemon.net> wrote: > > > Hey Boris, > > > > On Tue, Jan 13, 2015 at 09:52:07PM +0100, Boris Brezillon wrote: > > > On Tue, 13 Jan 2015 14:00:50 -0500 Jason Cooper <jason@lakedaemon.net> wrote: > > > > On Tue, Jan 13, 2015 at 07:46:18PM +0100, Boris Brezillon wrote: > > > > > Add documentation for the dumb demuxer. > > > > > > > > > > Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> > > > > > --- > > > > > .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ > > > > > 1 file changed, 34 insertions(+) > > > > > create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > > > > > > diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > new file mode 100644 > > > > > index 0000000..1c777ef > > > > > --- /dev/null > > > > > +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt > > > > > @@ -0,0 +1,34 @@ > > > > > +* Generic Dumb Interrupt Demultiplexer > > > > > + > > > > > +This Dumb demultiplixer simply forward all incoming interrupts to its > > > > > +enabled/unmasked children. > > > > > > > > Please forgive the potentially naïve question, but what hardware is this > > > > describing? > > > > > > That's not a real hardware per se, but on some hardware (like at91 SoCs) > > > some IRQ line are shared by several peripherals, and this dumb > > > demultiplex is here to represent such shared irq lines which cannot be > > > easily demultiplexed (because they do not provide a 'cause' > > > register). > > > > > > You can see it as a virtual irqchip provided to address broken hardware > > > designs. > > > > Hmm. Well, given tglx's recent reply, I suppose I'll *not* go down the > > rabbit hole of "the DT is for describing hardware." :-P > > Actually I'm a bit surprised no one else already mentioned that :-) (I > thought this would be the first complain regarding this dumb irq > demux chip). > > Anyway, IMHO, this can be considered as hardware description since > these irq-lines are really multiplexed into a single one... True, I think the issue is more that the DT node doesn't strictly represent a block of IP. We just need a way to make that clear in the binding doc. > > However, it would probably be a lot more palatable to the DT maintainers > > if we at least change the compatible to prepend "linux,". This way, if > > someone does come up with a better solution down the road, it will be > > much easier to deprecate the binding. > > > > I would also be amenable to "virt,", or "hack,", or even > > "work-around-piss-poor-hw,". Basically, anything that would indicate to > > consumers of the DT that this is not a true reflection of the hardware, > > and that it may be superseded by a better solution later. > > Actually I thought about changing it to "virtual,dumb-irq-demux" :-). Works for me. :) thx, Jason. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt new file mode 100644 index 0000000..1c777ef --- /dev/null +++ b/Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt @@ -0,0 +1,34 @@ +* Generic Dumb Interrupt Demultiplexer + +This Dumb demultiplixer simply forward all incoming interrupts to its +enabled/unmasked children. + +Required properties: +- compatible: Should be "irqchip-dumb-demux". +- interrupt-controller: Identifies the node as an interrupt controller. +- interrupts-extended or interrupt-parent and interrupts: Reference the source + interrupt connected to this dumb demuxer. +- #interrupt-cells: The number of cells to define the interrupts (should be 1). + The only cell is the IRQ number. +- irqs: u32 bitfield specifying the interrupts provided by the demuxer. + +Examples: + /* + * Dumb demuxer controller + */ + dumb_irq1_demux: dumb-irq-demux@1 { + compatible = "irqchip-dumb-demux"; + interrupt-controller; + #interrupt-cells = <1>; + interrupts-extended = <&aic 1 IRQ_TYPE_LEVEL_HIGH 7>; + irqs = <0x3f>; + }; + + /* + * Device connected on this dumb demuxer + */ + dma: dma-controller@ffffec00 { + compatible = "atmel,at91sam9g45-dma"; + reg = <0xffffec00 0x200>; + interrupts-extended = <&dumb_irq1_demux 0>; + };
Add documentation for the dumb demuxer. Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> --- .../bindings/interrupt-controller/dumb-demux.txt | 34 ++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 Documentation/devicetree/bindings/interrupt-controller/dumb-demux.txt