linux-kernel - Re: [PATCH] MIPS: Introduce cmdline argument writecombine=

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Message-ID: <20200806165212.GA2754@alpha.franken.de>
Date:   Thu, 6 Aug 2020 18:52:12 +0200
From:   Thomas Bogendoerfer <tsbogend@...ha.franken.de>
To:     Jiaxun Yang <jiaxun.yang@...goat.com>
Cc:     Tiezhu Yang <yangtiezhu@...ngson.cn>,
        Huacai Chen <chenhc@...ote.com>, linux-mips@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MIPS: Introduce cmdline argument writecombine=

On Thu, Aug 06, 2020 at 07:56:20PM +0800, Jiaxun Yang wrote:
> Our current problem is Loongson's writecombine implementation seems buggy.
> This is our platform issue rather than target hardware issue.

ok, so simply clear cpu_data[0].writecombine for the fauly parts

> And we don't even know which hardware is known to be good. The same graphic
> card became a different story on different user's hand.

find out what is broken and add the needed workarounds then.

> I understood what Teizhu thought. For entry-level users, we don't want to
> trouble
> them, so we have writecombine disabled by default. However, for advanced
> user
> trying to tweak their system, we should leave a switch for them to get it
> back.

IMHO if we do it that way, we end up with millions of knobs for tweaking
broken hardware, and nobody knows what's exactly broken. Sorry I won't go
that way.

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