From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx4+64zoDl5gC7egs3ABzDCdZDfQglGyT5kSb4CTuNpZbrSGRLnLcoAwSGJ7BQRUfCfxzkIrk ARC-Seal: i=1; a=rsa-sha256; t=1523970051; cv=none; d=google.com; s=arc-20160816; b=OhNBwUkUe45Lp0ObhP0fJIydI9eYsh+jmNtoiKh9nl1HMrTVBoBvVVKhzBKsihv6zC tceGTnZKskCCQx43nKMfUzmDs3iSOXKZ18BQwT57xNVCSymwSgbnOlQwS5FQw5DexEAU vletkMk2xZP8K0dUx1aadehTDPQ0blaDA91oC+MBssluoaa9SrqP6UGqEKyNznfC6F1I yswRhRrBzKXsmEd9IdxHMY+lPehulbLznBGmr7WiDNK9BebhZcfZRpIVHPy74Fd2A6Hw q6Bp/klpGjzLTUIVeG97j5j+WKh2jC6dDqlAD4MyaPYDq/tBe0HHR07Rr4xi2ElGtyay BsfA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=wNkpQkf9I/0o9gsqCau7bVLlimMLgvSnYja4kBOyRyQ=; b=ayLOtMmLeG/Qog9gtcjcVvX10/xmwTs1gxbA+sgqkncln6ixRD0Ffe0biOiZ9wcIdY 8XNo2iyGcvKU+D+YggHBgFblAVD7z9JOU5sr3AAQriD/bZJTYcbGRfHqL0XP2NzHynut VRtwYG9qyLZsFm+S15jsoN6cuaLkpK5P7N5V6osdDMrZrhmHTSZzWVrr1E7Q2XoFSS5n 15DmDVWUYyB0TGogS7AvQfHlSNPGuKONMzD6Wo4Ij2GMlMI/dLktD0SPjhVG4Scydrm5 vqDXHMHXqAaKXNtM5ckENlOIrCNiDxN2Aelji8VnHUllyfk7UP5HWEaia+/qrjTT5GFP EKbQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=HuINp5SQ; spf=pass (google.com: best guess record for domain of batv+1a17e12b704b27f00da8+5350+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+1a17e12b704b27f00da8+5350+infradead.org+hch@bombadil.srs.infradead.org Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=HuINp5SQ; spf=pass (google.com: best guess record for domain of batv+1a17e12b704b27f00da8+5350+infradead.org+hch@bombadil.srs.infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=BATV+1a17e12b704b27f00da8+5350+infradead.org+hch@bombadil.srs.infradead.org Date: Tue, 17 Apr 2018 06:00:40 -0700 From: 'Christoph Hellwig' To: Thomas Gleixner Cc: David Wang , 'Christoph Hellwig' , mingo@redhat.com, hpa@zytor.com, gregkh@linuxfoundation.org, x86@kernel.org, linux-kernel@vger.kernel.org, brucechang@via-alliance.com, cooperyan@zhaoxin.com, qiyuanwang@zhaoxin.com, benjaminpan@viatech.com, lukelin@viacpu.com, timguo@zhaoxin.com Subject: Re: [PATCH] x86/dma-mapping: override via_no_dac for new VIA PCI bridges Message-ID: <20180417130040.GA9426@infradead.org> References: <000001d3d628$4e91a4c0$ebb4ee40$@zhaoxin.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.2 (2017-12-15) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597894379144798679?= X-GMAIL-MSGID: =?utf-8?q?1597998418827866083?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, Apr 17, 2018 at 10:54:37AM +0200, Thomas Gleixner wrote: > The question was rather to have a list of PCI IDs for those chipsets which > have the problem and set the 'disable' flag only for those. That makes a lot > more sense than making a list of new chips which disable the disable flag. Agreed. There are a few other things I'd like to do in this area while we're at it (I'm happy to do the work, not trying to offload it to David or Thomas): (1) make the nodac flag a per-device flag. Set for every device under one of the affected VIA bridges, or for all PCI devices if the nodac command line option is used (2) move that flag into the common struct device (or the to be designed dma struct hanging off it in the future) and make that bit handled in common code as there is a common Xilinx host bridge with a 32-bit dma limitation (3) kill of the forcesac option, which was a strange performance tweak back in plain PCI days, which probably didn't even work as expected to start with.