> -----Original Message----- > From: Zev Weiss <[email protected]> > Sent: Wednesday, December 23, 2020 11:54 AM > To: Ryan Chen <[email protected]> > Cc: Joel Stanley <[email protected]>; Eddie James <[email protected]>; > Mauro Carvalho Chehab <[email protected]>; Andrew Jeffery > <[email protected]>; [email protected]; OpenBMC Maillist > <[email protected]>; Linux ARM > <[email protected]>; linux-aspeed > <[email protected]>; Linux Kernel Mailing List > <[email protected]>; Jae Hyun Yoo <[email protected]> > Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > unconditionally > > On Tue, Dec 22, 2020 at 08:53:33PM CST, Ryan Chen wrote: > >> -----Original Message----- > >> From: Joel Stanley <[email protected]> > >> Sent: Wednesday, December 23, 2020 9:07 AM > >> To: Zev Weiss <[email protected]>; Ryan Chen > >> <[email protected]> > >> Cc: Eddie James <[email protected]>; Mauro Carvalho Chehab > >> <[email protected]>; Andrew Jeffery <[email protected]>; > >> [email protected]; OpenBMC Maillist > >> <[email protected]>; Linux ARM > >> <[email protected]>; linux-aspeed > >> <[email protected]>; Linux Kernel Mailing List > >> <[email protected]>; Jae Hyun Yoo > >> <[email protected]> > >> Subject: Re: [PATCH 2/3] aspeed-video: clear spurious interrupt bits > >> unconditionally > >> > >> On Tue, 22 Dec 2020 at 19:14, Zev Weiss <[email protected]> wrote: > >> > > >> > On Mon, Dec 21, 2020 at 10:47:37PM CST, Joel Stanley wrote: > >> > >On Tue, 15 Dec 2020 at 02:46, Zev Weiss <[email protected]> > wrote: > >> > >> > >> > >> Instead of testing and conditionally clearing them one by one, > >> > >> we can instead just unconditionally clear them all at once. > >> > >> > >> > >> Signed-off-by: Zev Weiss <[email protected]> > >> > > > >> > >I had a poke at the assembly and it looks like GCC is clearing the > >> > >bits unconditionally anyway, so removing the tests provides no change. > >> > > > >> > >Combining them is a good further optimization. > >> > > > >> > >Reviewed-by: Joel Stanley <[email protected]> > >> > > > >> > >A question unrelated to this patch: Do you know why the driver > >> > >doesn't clear the status bits in the interrupt handler? I would > >> > >expect it to write the value of sts back to the register to ack > >> > >the pending interrupt. > >> > > > >> > > >> > No, I don't, and I was sort of wondering the same thing actually -- > >> > I'm not deeply familiar with this hardware or driver though, so I > >> > was a bit hesitant to start messing with things. (Though maybe > >> > doing so would address the "stickiness" aspect when it does > >> > manifest.) Perhaps Eddie or Jae can shed some light here? > >> > >> I think you're onto something here - this would be why the status > >> bits seem to stick until the device is reset. > >> > >> Until Aspeed can clarify if this is a hardware or software issue, I > >> suggest we ack the bits and log a message when we see them, instead > >> of always ignoring them without taking any action. > >> > >> Can you write a patch that changes the interrupt handler to ack > >> status bits as it handles each of them? > >> > >Hello Zev, before the patch, do you met issue with irq handler? > >[continuous incoming?] > > > >In aspeed_video_irq handler should only handle enable interrupt expected. > > u32 sts = aspeed_video_read(video, VE_INTERRUPT_STATUS); > > + sts &= aspeed_video_read(video, VE_INTERRUPT_CTRL); > > > >Ryan > > > > Hi Ryan, > > Prior to any of these patches I encountered a problem pretty much exactly like > what Jae described in his commit message in 65d270acb2d (but the kernel I > was running included that patch). Adding the diagnostic in patch #1 of this > series showed that it was apparently the same problem, just with a different > interrupt that Jae's patch didn't include. > > From what you wrote above, I gather that it is in fact expected for the > hardware to assert interrupts that aren't enabled in VE_INTERRUPT_CTRL? > If so, I guess something like that would obviate the need for both Jae's > earlier > patch and this whole series. > Yes, I expected handle enabled in VE_INTERRUPT_CTRL.
> I think the question Joel raised is somewhat independent though -- if the > VE_INTERRUPT_STATUS register asserts interrupts we're not actually using, > should the driver acknowledge them anyway or just leave them alone? My opinion will keep them alone, ignore them. > (Though if we're just going to ignore them anyway maybe it doesn't ultimately > matter very much.) > > > Zev
