On 23 July 2014 20:40, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote: > On Wed, Jul 16, 2014 at 12:43 PM, Grygorii Strashko > <grygorii.strashko@xxxxxx> wrote: > >> From: Murali Karicheri <m-karicheri2@xxxxxx> >> >> On Keystone SOCs, ARM host can send interrupts to DSP cores using the >> DSP GPIO controller IP. Each DSP GPIO controller provides 28 IRQ signals for >> each DSP core. This is one of the component used by the IPC mechanism used >> on Keystone SOCs. >> >> Keystone 2 DSP GPIO controller has specific features: >> - each GPIO can be configured only as output pin; >> - setting GPIO value to 1 causes IRQ generation on target DSP core; >> - reading pin value returns 0 - if IRQ was handled or 1 - IRQ is still >> pending. >> >> Signed-off-by: Murali Karicheri <m-karicheri2@xxxxxx> >> Signed-off-by: Grygorii Strashko <grygorii.strashko@xxxxxx> > > Pardon me. How is this GENERAL PURPOSE Input/Output? > > It seems very very much SPECIAL PURPOSE to me, it's like > you're just shoehorning some IPC mechanism into the GPIO > subsystem, and this may be because the datasheet calls it > GPIO when it's not. > > What other stuff than DSP is connected to these lines, and is it > really even external lines? Aren't these just polysilicon rails > pretty much hammered to be used by the DSP and nothing else. > > What is the difference between this and a mailbox IRQ line > and the kind of stuff handled by drivers/mailbox? > > I'd like Suman and Jassi to have a look at this to see if it's > actually a mailbox before we proceed. > The controller seems like most others, only incapable of reading signals (output only). The userspace driving those signals to communicate with a DSP isn't enough to call it a mailbox usecase, because on a different board the userspace may drive those signals to control LEDs :) Cheers, Jassi -- 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
