From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8B6A4C433F5 for ; Mon, 11 Oct 2021 13:41:36 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 28DB060E8B for ; Mon, 11 Oct 2021 13:41:36 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 28DB060E8B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:CC:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=g/kpGx8rKu6NMtjD2QN8RdQVyjKBlypMHpfSLZYLgD8=; b=a5rFacZv1beupVJuuHKVFBldJL 8X1mOTZR+IrS5QmD7jlkIHu4nppXkVomxeVI41IeNMf5WLlNwGteODuSwe0ePox5/sexKrxWajF/F kmdV28cTwlZc7LgkNUE+8Jjso/pUtUFn2LTSI0nsf2u/Zj7uxxnDaXPcTF9GAMblM26rUCtulE4c0 VkCeFUN6pij+vtC2nmVkJJsW7tBySpuW6yPGwvbUpBFnnSDbFif/FYvymZ+RC6YmFpxJ7TQS5eQmY TRjCQvw6+GfW7PSKtqW9nHYHlh5gTRKumf3cSRbrMVhMQ/m6MSB/1+5ry6+y53WPKDklxTKNJUyEP uf36MNWQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mZvWE-009YoR-0E; Mon, 11 Oct 2021 13:39:06 +0000 Received: from szxga08-in.huawei.com ([45.249.212.255]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mZvV9-009YFA-4d for linux-arm-kernel@lists.infradead.org; Mon, 11 Oct 2021 13:38:01 +0000 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.55]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4HSfvk0XtBz1DHTC; Mon, 11 Oct 2021 21:36:18 +0800 (CST) Received: from kwepemm600016.china.huawei.com (7.193.23.20) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 11 Oct 2021 21:37:52 +0800 Received: from [10.67.102.67] (10.67.102.67) by kwepemm600016.china.huawei.com (7.193.23.20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Mon, 11 Oct 2021 21:37:52 +0800 Subject: Re: [PATCH net-next 2/4] io: add function to flush the write combine buffer to device immediately To: Will Deacon CC: , , , , , , , , , , , , References: <1627614864-50824-1-git-send-email-huangguangbin2@huawei.com> <1627614864-50824-3-git-send-email-huangguangbin2@huawei.com> <20210730090056.GA22968@willie-the-truck> From: "huangguangbin (A)" Message-ID: <01474da2-0a7d-3e6a-9f8e-401d36c8f12e@huawei.com> Date: Mon, 11 Oct 2021 21:37:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: <20210730090056.GA22968@willie-the-truck> X-Originating-IP: [10.67.102.67] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600016.china.huawei.com (7.193.23.20) X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211011_063759_709851_43087406 X-CRM114-Status: GOOD ( 20.78 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021/7/30 17:00, Will Deacon wrote: > Hi, > > On Fri, Jul 30, 2021 at 11:14:22AM +0800, Guangbin Huang wrote: >> From: Xiongfeng Wang >> >> Device registers can be mapped as write-combine type. In this case, data >> are not written into the device immediately. They are temporarily stored >> in the write combine buffer and written into the device when the buffer >> is full. But in some situation, we need to flush the write combine >> buffer to device immediately for better performance. So we add a general >> function called 'flush_wc_write()'. We use DGH instruction to implement >> this function for ARM64. >> >> Signed-off-by: Xiongfeng Wang >> Signed-off-by: Guangbin Huang >> --- >> arch/arm64/include/asm/io.h | 2 ++ >> include/linux/io.h | 6 ++++++ >> 2 files changed, 8 insertions(+) > > -ENODOCUMENTATION > Hi Will, may I consult you which document file is good to add documentation? >> diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h >> index 7fd836bea7eb..5315d023b2dd 100644 >> --- a/arch/arm64/include/asm/io.h >> +++ b/arch/arm64/include/asm/io.h >> @@ -112,6 +112,8 @@ static inline u64 __raw_readq(const volatile void __iomem *addr) >> #define __iowmb() dma_wmb() >> #define __iomb() dma_mb() >> >> +#define flush_wc_write() dgh() > > I think it would be worthwhile to look at what architectures other than > arm64 offer here. For example, is there anything similar to this on riscv, > x86 or power? Doing a quick survery of what's out there might help us define > a macro that can be used across multiple architectures. > > Thanks, > > Will > >> /* >> * Relaxed I/O memory access primitives. These follow the Device memory >> * ordering rules but do not guarantee any ordering relative to Normal memory >> diff --git a/include/linux/io.h b/include/linux/io.h >> index 9595151d800d..469d53444218 100644 >> --- a/include/linux/io.h >> +++ b/include/linux/io.h >> @@ -166,4 +166,10 @@ static inline void arch_io_free_memtype_wc(resource_size_t base, >> } >> #endif >> >> +/* IO barriers */ >> + >> +#ifndef flush_wc_write >> +#define flush_wc_write() do { } while (0) >> +#endif >> + >> #endif /* _LINUX_IO_H */ >> -- >> 2.8.1 >> > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel