On Fri, 17 Aug 2018, Arnd Bergmann wrote:
> On Fri, Aug 17, 2018 at 9:10 PM Mikulas Patocka <mpato...@redhat.com> wrote:
> >
> > Hi
> >
> > The commit 9ce8654323d69273b4977f76f11c9e2d345ab130 breaks the Alpha
> > Avanti platform. There is temporary 40-second hang during boot when
> > detecting serial ports (although the hang eventually resolves and the
> > machine boots) and there's total hang during shutdown when saving the
> > hardware clock.
> >
> > The bug can be fixed with the patch below - apparently, there's something
> > in the Alpha Avanti platform code that expects that the barrier should be
> > after the I/O write instructions.
>
> I have two theories here:
>
> - there might be a driver oddity (can't really call it bug) that
> relies on writel()
> etc to imply a barrier afterwards when that guarantee isn't there elsewhere
>
> - For outb()/outw()/outl(), we ought to provide stronger barriers than for
> writeb()/writew()/writel(), as PCI drivers should expect the store to have
> arrived at the device by the time the function returns.
>
> Could you try the patch below that would address the second issue but not
> the first?
>
> Arnd
I've tried this patch and it doesn't help.
Mikulas
> diff --git a/arch/alpha/include/asm/io.h b/arch/alpha/include/asm/io.h
> index 4c533fc94d62..0a479ac27cab 100644
> --- a/arch/alpha/include/asm/io.h
> +++ b/arch/alpha/include/asm/io.h
> @@ -364,11 +364,13 @@ extern inline u16 inw(unsigned long port)
> extern inline void outb(u8 b, unsigned long port)
> {
> iowrite8(b, ioport_map(port, 1));
> + mb();
> }
>
> extern inline void outw(u16 b, unsigned long port)
> {
> iowrite16(b, ioport_map(port, 2));
> + mb();
> }
> #endif
>
> @@ -394,6 +396,7 @@ extern inline u32 inl(unsigned long port)
> extern inline void outl(u32 b, unsigned long port)
> {
> iowrite32(b, ioport_map(port, 4));
> + mb();
> }
> #endif
>
