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

Hi Adrian,

On Mon, Apr 29, 2024 at 10:22 AM John Paul Adrian Glaubitz
<[email protected]> wrote:
> On Mon, 2024-04-29 at 10:06 +0200, Geert Uytterhoeven wrote:
> > On Mon, Apr 29, 2024 at 9:52 AM John Paul Adrian Glaubitz
> > <[email protected]> wrote:
> > >
> > > Don't have the 32-bit SH CPUs any caches? The code itself is unconditionally executed,
> > > it seems.
> >
> > They do. E.g. SH7751 has 8+8 KiB of L1 cache.
> > But e.g. sh7724 has 32+32KiB L1 cache, and 256 KiB of unified L2 cache.
> > SH772[34] have l2_cache_init() to enable the L2 cache, so probably they
> > boot with L2 disabled, and we are fine.
>
> Understood. But what exactly was the job of cache_control() when all it
> does was flushing the cache area? The cache is not enabled or disabled

I assume flushing the cache was needed to push all code written to RAM.

> here, is it?

No, it is not enabled or disabled. Probably that was planned for later,
cfr. the command parameter.

> Also, I was wondering whether this could be related to the boot lockups
> that I am seeing on my SH-7786LCR which stops after printing "Uncompressing
> Linux...".

I doubt it, unless reading from 0x80000000 causes a lock-up...


> I will test later this week whether your patch actually fixes this issue.

... in which case my patch will help ;-)

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds