Hi Marc. On Wed, 10 Feb 2021 at 15:30, Marc Zyngier <maz@xxxxxxxxxx> wrote: > > 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@xxxxxxxxxx> 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... :-/ Thanks for the info. Option 3 - remove l2-intc and drop back to polling the i2c-brcmstb blocks (which the driver supports anyway). HDMI I2C generally isn't heavily used once displays are connected, so I'd be OK with that. (We can keep the l2-intc that handles CEC and HPD as that is on a unique GIC interrupt). Dave
