From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E745572 for ; Wed, 19 May 2021 05:48:37 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id BE74F6139A for ; Wed, 19 May 2021 05:48:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1621403316; bh=1M/78skAnJ0O2EA7jNQp+kPITl517U87tfk5kFLTNwo=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=lncOtVDAEu7HiiRH4NkTlbuFCw039Zi8FHl47j/D8o8b6429d7pMItzt92Zuqn/md 1k+rbV+ujbbDaXukjm0H+1NkPpRruxJUxHosKCKcTPnfO6GNB2cIPjYaZNGrcS4NaE GHVDbor7fM1s6Abpb3MI0t36fipqE5D8L9qat0/El/+e3kqejTkZ/+k+/nWPZ1mAzc PuHDXrty+uIaYvgimxcHDmatLZfVnBz1m9NmKx/pMsYHPhhU/LaDAkRTimQGn8DGza QJUH2Wr6BcISqxxFuI7L3y/p6NxUoWyT+xqpmuXHfj3/CzbkZ80qIsBFio5u6tyKDc Ze99bV9iojkDQ== Received: by mail-lf1-f49.google.com with SMTP id h4so17295204lfv.0 for ; Tue, 18 May 2021 22:48:36 -0700 (PDT) X-Gm-Message-State: AOAM532VAObZYva9cIGVW4/lvZROd5lydsJf8jq+SCGAQwChRLoMZwtP xpK2e5dNKZUCMedVjlyDQ1W61GnoWds2hunht5A= X-Google-Smtp-Source: ABdhPJyZmJGTwo2722UUz7WdRiEPE80dASqU/bVhjb4FY4dMa4G28pS/d7JsiaV39IWXLH9tUctL90X9qaaj9JfV8T0= X-Received: by 2002:ac2:5493:: with SMTP id t19mr7208809lfk.346.1621403315041; Tue, 18 May 2021 22:48:35 -0700 (PDT) X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <1621400656-25678-1-git-send-email-guoren@kernel.org> <20210519052048.GA24853@lst.de> In-Reply-To: <20210519052048.GA24853@lst.de> From: Guo Ren Date: Wed, 19 May 2021 13:48:23 +0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH RFC 0/3] riscv: Add DMA_COHERENT support To: Christoph Hellwig Cc: Anup Patel , Palmer Dabbelt , drew@beagleboard.org, wefu@redhat.com, lazyparser@gmail.com, linux-riscv , Linux Kernel Mailing List , linux-arch , linux-sunxi@lists.linux.dev, Guo Ren Content-Type: text/plain; charset="UTF-8" On Wed, May 19, 2021 at 1:20 PM Christoph Hellwig wrote: > > On Wed, May 19, 2021 at 05:04:13AM +0000, guoren@kernel.org wrote: > > From: Guo Ren > > > > The RISC-V ISA doesn't yet specify how to query or modify PMAs, so let > > vendors define the custom properties of memory regions in PTE. > > Err, hell no. The ISA needs to gets this fixed first. Then we can > talk about alternatives patching things in or trapping in the SBI. > But if the RISC-V ISA can't get these basic done after years we can't > support it in Linux at all. The patchset just leaves a configuration chance for vendors. Before RISC-V ISA fixes it, we should give the chance to let vendor solve their real chip issues. -- Best Regards Guo Ren ML: https://lore.kernel.org/linux-csky/