Message-ID: <109608ce770c2da249a7624f55666da640260f28.camel@xry111.site>
Subject: Re: [PATCH] LoongArch: Make WriteCombine configurable for ioremap()
From:   Xi Ruoyao <xry111@xry111.site>
To:     Huacai Chen <chenhuacai@kernel.org>
Cc:     Huacai Chen <chenhuacai@loongson.cn>, loongarch@lists.linux.dev,
        Xuefeng Li <lixuefeng@loongson.cn>,
        Guo Ren <guoren@kernel.org>, Xuerui Wang <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        linux-kernel@vger.kernel.org, loongson-kernel@lists.loongnix.cn
Date:   Tue, 14 Mar 2023 18:10:46 +0800
In-Reply-To: <CAAhV-H4TpQuq9sE2H=zbO8cvwn3Aer_pu1a-DU9L9OSR1bQX=g@mail.gmail.com>
References: <20230314085433.4078119-1-chenhuacai@loongson.cn>
         <21f5aba50b7732b48d2610a5015186adf6bdfb38.camel@xry111.site>
         <CAAhV-H4TpQuq9sE2H=zbO8cvwn3Aer_pu1a-DU9L9OSR1bQX=g@mail.gmail.com>
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On Tue, 2023-03-14 at 18:02 +0800, Huacai Chen wrote:
> > Hmm, is it possible to make a PCI quirk so SUC/WUC will be decided
> > automatically from the vendor:device ID of the PCI root controller?
> > Then we don't need to rely on the user or distro maintainer to select a=
n
> > option.=C2=A0 I see there is already many architecture-dependant #if
> > directives in drivers/pci/quirks.c so I guess such a quirk is acceptabl=
e
> > in PCI tree...
> Not a good idea, pci quirks need too long a time to review, and we
> don't know when this issue can be fixed in hardware.

How about make a PCI fixup in arch/loongarch/pci/pci.c then?  I think we
just need to set a flag in the fixup, then check the flag in
ioremap_wc...

--=20
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University