linux-kernel - Re: [PATCH] MIPS: ralink: mt7621: do memory detection on KSEG1

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Message-ID: <20220217075829.GA5185@alpha.franken.de>
Date:   Thu, 17 Feb 2022 08:58:29 +0100
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Chuanhong Guo <gch981213@...il.com>
Cc:     linux-mips@...r.kernel.org, Rui Salvaterra <rsalvaterra@...il.com>,
        Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: ralink: mt7621: do memory detection on KSEG1

On Thu, Feb 17, 2022 at 12:06:09PM +0800, Chuanhong Guo wrote:
> Hi!
> 
> On Thu, Feb 17, 2022 at 3:57 AM Thomas Bogendoerfer
> <tsbogend@...ha.franken.de> wrote:
> >
> > On Fri, Feb 11, 2022 at 08:13:44AM +0800, Chuanhong Guo wrote:
> > > It's reported that current memory detection code occasionally detects
> > > larger memory under some bootloaders.
> > > Current memory detection code tests whether address space wraps around
> > > on KSEG0, which is unreliable because it's cached.
> > >
> > > Rewrite memory size detection to perform the same test on KSEG1 instead.
> > > While at it, this patch also does the following two things:
> > > 1. use a fixed pattern instead of a random function pointer as the magic
> > >    value.
> > > 2. add an additional memory write and a second comparison as part of the
> > >    test to prevent possible smaller memory detection result due to
> > >    leftover values in memory.
> > >
> > > Fixes: 139c949f7f0a MIPS: ("ralink: mt7621: add memory detection support")
> > > Reported-by: Rui Salvaterra <rsalvaterra@...il.com>
> > > Signed-off-by: Chuanhong Guo <gch981213@...il.com>
> > > ---
> > >  arch/mips/ralink/mt7621.c | 36 +++++++++++++++++++++++-------------
> > >  1 file changed, 23 insertions(+), 13 deletions(-)
> >
> > applied to mips-fixes.
> 
> Oops.
> 
> As I mentioned in a previous mail, this patch has two cosmetic problems:
> 1. misplaced bracket in commit message "Fixes" tag
> 2. incorrect second test pattern: I meant to flip all the bits in the
> first pattern,
>    but I used "!" instead of "~". Any value will work just fine but it
> looks weird
>    to construct a zero using !MT7621_MEM_TEST_PATTERN.
> 
> Should I send a second patch to fix this patch or send a v2 of the
> original patch?

a second patch please.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]