Re: [PATCH] sh: boot: Remove sh5 cache handling

On Mon, 2024-04-29 at 09:49 +0200, Geert Uytterhoeven wrote:
> Hi Adrian,
> 
> On Mon, Apr 29, 2024 at 9:46 AM John Paul Adrian Glaubitz
> <[email protected]> wrote:
> > On Wed, 2024-04-24 at 13:54 +0200, Geert Uytterhoeven wrote:
> > > Commit 37744feebc086908 ("sh: remove sh5 support") in v5.8 forgot to
> > > remove the sh5 cache handling.
> > > 
> > > Suggested-by: Yoshinori Sato <[email protected]>
> > > Signed-off-by: Geert Uytterhoeven <[email protected]>
> 
> > > --- a/arch/sh/boot/compressed/cache.c
> > > +++ /dev/null
> > > @@ -1,13 +0,0 @@
> > > -// SPDX-License-Identifier: GPL-2.0
> > > -int cache_control(unsigned int command)
> > > -{
> > > -     volatile unsigned int *p = (volatile unsigned int *) 0x80000000;
> > > -     int i;
> > > -
> > > -     for (i = 0; i < (32 * 1024); i += 32) {
> > > -             (void)*p;
> > > -             p += (32 / sizeof(int));
> > > -     }
> > > -
> > > -     return 0;
> > > -}
> 
> > Interesting, looking at boot/compressed/cache.c, it seems that the whole code
> > is actually a no-op and does nothing but increasing a pointer. So I agree we
> > should just delete it.
> 
> It is not a no-op: it also reads from memory, to load new data in
> the cache, and evicting the old data.

Yeah, I actually came to this conclusion right after sending my reply. However, the
command parameter is never used.

Don't have the 32-bit SH CPUs any caches? The code itself is unconditionally executed,
it seems.

Adrian

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