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 X-Spam-Level: X-Spam-Status: No, score=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 298E3C4338F for ; Fri, 30 Jul 2021 09:03:02 +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 E4CE860FED for ; Fri, 30 Jul 2021 09:03:01 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E4CE860FED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=nMlsoR+2oVbhvAiem58J0/bXZXZ3Ig4Tp9TZ8tlEu1A=; b=ciUZYvKwIprkYE jLncHC5yAs76zrKxvNWgxXnUj5yfvDAVB8cBu3AF/4pqgYaygxipOGW2G6pFfjRe1H5eMNX2X6aWP tiTP30ZqOv4SnBv+fdoNABI3LqcZym5208/L2k+z0QiCUevxhwXOVKVkxb9IkWJ1YZcunT1/7pqfn HvRUl3GzS1TzmWs/xJuhthHpys0gEMIztBlJfkrUWJsVQbKuMB8QFb0joqaE4r6LvbwmZGiBjBl3e VMQDHFOjA/JDsG5oUa5XB3sU2NP7r0mBc+0VnZYuuIliWvaQDCR12tJzGS4ESQd3hM9nvmn+GUhmm j2VpIETvvUHovlPRS4WQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m9OOF-007n4I-NX; Fri, 30 Jul 2021 09:01:12 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1m9OO8-007n1t-3G for linux-arm-kernel@lists.infradead.org; Fri, 30 Jul 2021 09:01:08 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4DB2060EBC; Fri, 30 Jul 2021 09:01:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1627635663; bh=ZqUXtxocwsf9OoFzcWmFz4ZMIgWoSvnVSWDE/K9rjYc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gsqow/fRGqYWqMYX/Gxs1k8QH2DDnJhaEknI7ikudaKF79bQeRYbdBKX/y+Mf5U9a SmNghxm3s85lGNm1JT8JzX/97KQfutuYcRP3dWPWgeturv3mBMm2ITqaVIqCPS2upt 0baXwj7mBSJn1cZ3BDfMzMwcm8a3N3gY4OTRRjMylvYV/FhhuPrOtNgAR9kUjPEf9m CxaeCVfc+UoWO8f3dIM9qUgF3N8tWBPScbMURa3nrgq//bd+oSsV5J4+dDdtmb2/By g3CJvntp4P8ghwPpj5f12ShjzM8r2UfqWXMOQtHI9VYcwki3kCQNcdjnf5wauDAzsM Kxv8PJ68drXeA== Date: Fri, 30 Jul 2021 10:00:57 +0100 From: Will Deacon To: Guangbin Huang Cc: davem@davemloft.net, kuba@kernel.org, catalin.marinas@arm.com, maz@kernel.org, mark.rutland@arm.com, dbrazdil@google.com, qperret@google.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, lipeng321@huawei.com, peterz@infradead.org Subject: Re: [PATCH net-next 2/4] io: add function to flush the write combine buffer to device immediately Message-ID: <20210730090056.GA22968@willie-the-truck> References: <1627614864-50824-1-git-send-email-huangguangbin2@huawei.com> <1627614864-50824-3-git-send-email-huangguangbin2@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1627614864-50824-3-git-send-email-huangguangbin2@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210730_020104_225156_EE3B88EA X-CRM114-Status: GOOD ( 20.59 ) 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 > 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