On Mon, Mar 24, 2014 at 03:22:10PM -0400, Alan Stern wrote: > On Mon, 24 Mar 2014, Felipe Balbi wrote: > > > Hi, > > > > On Mon, Mar 24, 2014 at 09:21:40AM -0600, David Mosberger wrote: > > > Felipe, > > > > > > On Mon, Mar 24, 2014 at 7:31 AM, Felipe Balbi <ba...@ti.com> wrote: > > > > > > > Why do you need to run your IRQ handler when an URQ gets enqueued ? That > > > > doesn't make much sense :-s > > > > > > Please see the comments at the start of the file: spi_sync() is > > > blocking and must not be called while holding spinlocks or with > > > interrupts disabled. The purpose of max3421_spi_thread() is to handle > > > > sure, but this is why we have threaded IRQ support. > > > > > all SPI transactions (implicitly serializing them). An interrupt is > > > just one of the reasons to wake up the SPI thread. Adding URBs, > > > removing them, or performing a bus reset are other reasons. > > > > you didn't tell me why. Why do you need to run that inside the same > > thread ? Why can't you do that from inside ->urb_enqueue() itself ? > > > > > You can think of max3421_spi_thread() as implementing the state > > > machine that would normally be implemented in silicon with a "smart" > > > controller such as OHCI or similar. > > > > yada, yada, yada... still didn't answer my original question. > > It sounds like David is saying that he needs a process context to > communicate with the host controller over SPI, and this communication > has to take place whenever an URB is enqueued or dequeued as well as > whenever an interrupt occurs. > > If that's correct, it seems a kernel thread would be a better solution > than a threaded IRQ handler.
looking at the driver, there's still quite a bit of duplication between his kthread implementation and what threaded IRQs would give for free... I see what you're saying, from urb_enqueue the EP schedule needs to be advanced, so he needs to run his kthread and that might be alright, code still looks a bit fishy, though. -- balbi
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