linux-kernel - Re: About commit "io: change inX() to have their own IO barrier overrides"

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Message-ID: <e6ef4f8f-2fd6-5a1c-8539-abd7a9fcc5d1@kernel.org>
Date:   Fri, 6 Mar 2020 16:15:48 -0500
From:   Sinan Kaya <okaya@...nel.org>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     John Garry <john.garry@...wei.com>,
        "xuwei (O)" <xuwei5@...ilicon.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-arch <linux-arch@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>
Subject: Re: About commit "io: change inX() to have their own IO barrier
 overrides"

On 3/6/2020 2:54 AM, Arnd Bergmann wrote:
> The exact semantics of inl() and readl() are slightly different, so they
> have distinct sets of barriers in the asm-generic/io.h implementation.
> 
> For instance, the arm64 architectures defines in_par() as '__iormb(v)',
> but defines __io_ar() as a  '__rmb()'. Similarly, riscv defines them
> as "fence i,ior" and "fence i,r".

makes sense