Re: [PATCH] sh: Avoid using IRQ0 on SH3 and SH4

[Guenter Roeck]

On 7/6/23 07:01, John Paul Adrian Glaubitz wrote:
> Hi Guenter!
>
> On Thu, 2023-07-06 at 06:57 -0700, Guenter Roeck wrote:
> > On Thu, Jun 01, 2023 at 11:22:17PM +0300, Sergey Shtylyov wrote:
> > > IRQ0 is no longer returned by platform_get_irq() and its ilk -- they now
> > > return -EINVAL instead.  However, the kernel code supporting SH3/4-based
> > > SoCs still maps the IRQ #s starting at 0 -- modify that code to start the
> > > IRQ #s from 16 instead.
> > >
> > > The patch should mostly affect the AP-SH4A-3A/AP-SH4AD-0A boards as they
> > > indeed are using IRQ0 for the SMSC911x compatible Ethernet chip.
> >
> > Unfortunately it also affects all sh4 emulations in qemu, and results in
> > boot stalls with those. There isn't a relevant log to attach because there
> > is no error message - booting just stalls until the emulation is aborted.
> >
> > Reverting this patch fixes the problem.
> >
> > Bisect log is attached for reference. Note that bisect requires applying
> > commit 7497840d462c ("sh: Provide unxlate_dev_mem_ptr() in asm/io.h"),
> > which is also the reason why the problem was not observed earlier since
> > it was hiding behind a build failure.
>
> Interesting. My naive understanding was that IRQ0 is no longer usable in the
> kernel as Sergey claimed. Was that not correct?

I have no idea. All I know is that all my sh4 qemu emulations hang during boot
after this patch is applied. I don't have CONFIG_SMSC911X enabled in my builds.
I also don't see any error messages from failed IRQ requests after reverting
this patch.

Guenter