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[209.132.180.67]) by mx.google.com with ESMTP id i185si3242221oia.187.2019.12.19.05.57.01; Thu, 19 Dec 2019 05:57:13 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@xenosoft.de header.s=strato-dkim-0002 header.b=YEAUceQn; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726840AbfLSNzL (ORCPT + 99 others); Thu, 19 Dec 2019 08:55:11 -0500 Received: from mo4-p01-ob.smtp.rzone.de ([85.215.255.52]:36985 "EHLO mo4-p01-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726760AbfLSNzL (ORCPT ); Thu, 19 Dec 2019 08:55:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1576763707; s=strato-dkim-0002; d=xenosoft.de; h=In-Reply-To:Date:Message-ID:References:Cc:To:From:Subject: X-RZG-CLASS-ID:X-RZG-AUTH:From:Subject:Sender; bh=kI2ukjRy7KCFsfSWtfjMgsGPbi2sbVneeGOg1X7LIV8=; b=YEAUceQn6QazfdesBsc7kq7wu32oddWtG0x8ZFzA5SAgf87tCs5MuSXc6cVDqJV8Sk Ip8uc7MpD9C59eNDNRS2/GUMdq/wRKSLq8HV8w8d+R2aoGrHjvvFrzLo9dxYDGGn4Gmu RX2vBgyamQmvkk4LCowX5Ipd7N+bty58IQzSz/Tw2F9UiNJAA0k1h6Rowya8EAdfAf0q 5UbK3cv9ZS6ZAN9ymq0HmSPVczYFkKF69rHfmWA3KCUSAuVrOlGoiYsLnuIEX9rruluG ey6mCVbWjsjMjX+HZmEVgqHavhfdvU/8kqRGWzapHDIZIveK3qyJIvivI3+uu64Mm6DH 7fkw== X-RZG-AUTH: ":L2QefEenb+UdBJSdRCXu93KJ1bmSGnhMdmOod1DhGM4l4Hio94KKxRySfLxnHfJ+Dkjp5DdBJSrwuuqxvPhSIk4IhhIsapUrtwdiemkXf6zUCQ==" X-RZG-CLASS-ID: mo00 Received: from [IPv6:2a02:8109:89c0:ebfc:141e:1690:4104:28ad] by smtp.strato.de (RZmta 46.1.1 AUTH) with ESMTPSA id 40080evBJDsS14t (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Thu, 19 Dec 2019 14:54:28 +0100 (CET) Subject: Re: use generic DMA mapping code in powerpc V4 From: Christian Zigotzky To: Michael Ellerman , Christoph Hellwig , Benjamin Herrenschmidt , Paul Mackerras Cc: linux-arch@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, "R.T.Dickinson" , "contact@a-eon.com" , mad skateman , Darren Stevens References: <20181114082314.8965-1-hch@lst.de> <20181127074253.GB30186@lst.de> <87zhttfonk.fsf@concordia.ellerman.id.au> <535776df-dea3-eb26-6bf3-83f225e977df@xenosoft.de> Message-ID: Date: Thu, 19 Dec 2019 14:54:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <535776df-dea3-eb26-6bf3-83f225e977df@xenosoft.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: de-DE Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi All, We still have some issues with PCI cards in our FSL P5020 and P5040 systems since the DMA mapping updates. [1, 2] We have to limit the RAM to 3500MB for some problematic PCI cards. (kernel boot argument 'mem=3500M') The problematic DMA mapping code was added with the PowerPC updates 4.21-1 to the official kernel source code last year. [3] We have created a bug report. [4] The old 4.x kernels aren't affected because they use the old DMA code. Please check the new DMA code again. Thanks, Christian [1] http://forum.hyperion-entertainment.com/viewtopic.php?f=58&p=49486#p49486 [2] http://forum.hyperion-entertainment.com/viewtopic.php?f=58&t=4349&start=50#p49099 [3] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d6973327ee84c2f40dd9efd8928d4a1186c96e2 [4] https://bugzilla.kernel.org/show_bug.cgi?id=205201 On 28 November 2018 at 4:55 pm, Christian Zigotzky wrote: > On 28 November 2018 at 12:05PM, Michael Ellerman wrote: >> Nothing specific yet. >> >> I'm a bit worried it might break one of the many old obscure platforms >> we have that aren't well tested. >> > Please don't apply the new DMA mapping code if you don't be sure if it > works on all supported PowerPC machines. Is the new DMA mapping code > really necessary? It's not really nice, to rewrote code if the old > code works perfect. We must not forget, that we work for the end > users. Does the end user have advantages with this new code? Is it > faster? The old code works without any problems. I am also worried > about this code. How can I test this new DMA mapping code? > > Thanks > >