Messages in this thread | | | Date | Wed, 10 Feb 2021 15:30:45 +0000 | From | Marc Zyngier <> | Subject | Re: [PATCH v2 14/15] ARM: dts: bcm2711: Add the BSC interrupt controller |
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Hi Maxime,
On 2021-02-10 14:40, Maxime Ripard wrote: > Hi Dave, > > On Tue, Feb 09, 2021 at 09:49:05AM +0000, Dave Stevenson wrote: >> On Mon, 11 Jan 2021 at 14:23, Maxime Ripard <maxime@cerno.tech> wrote: >> > >> > The BSC controllers used for the HDMI DDC have an interrupt controller >> > shared between both instances. Let's add it to avoid polling. >> >> This seems to have unintended side effects. >> GIC interrupt 117 is shared between the standard I2C controllers >> (i2c-bcm2835) and the l2-intc block handling the HDMI I2C interrupts. >> >> Whilst i2c-bcm2835 requests the interrupt with IRQF_SHARED, that >> doesn't appear to be an option for l2-intc registering as an interrupt >> controller. i2c-bcm2835 therefore loses out and fails to register for >> the interrupt. >> >> Is there an equivalent flag that an interrupt controller can add to >> say that the parent interrupt is shared? Is that even supported? > > Indeed, it looks like setting an equivalent to IRQF_SHARED would be the > solution, but I couldn't find anything that would allow us to in the > irqchip code. > > Marc, Thomas, is it something that is allowed?
No, not really. That's because the chained handler is actually an interrupt flow, and not a normal handler. IRQF_SHARED acts at the wrong level for that.
I can see two possibilities:
- the l2-intc gets turned into a normal handler, and does the demux from there. Horrible stuff.
- the i2c controller gets parented to the l2c-int as a fake interrupt, and gets called from there. Horrible stuff.
Pick your poison... :-/
M. -- Jazz is not dead. It just smells funny...
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