From mboxrd@z Thu Jan 1 00:00:00 1970 From: Malcolm Gillies Subject: Re: CompactFlash and HD unhappy together on the same IDE channel Date: Sun, 19 Aug 2007 20:43:16 +1000 Message-ID: <46C81EC4.9080407@ouabain.org> References: <46C69913.1060505@g7.org> <46C799E8.8080407@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from webmail.icp-qv1-irony3.iinet.net.au ([203.59.1.108]:14477 "EHLO webmail.icp-qv1-irony3.iinet.net.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750779AbXHSKnZ (ORCPT ); Sun, 19 Aug 2007 06:43:25 -0400 In-Reply-To: <46C799E8.8080407@rtr.ca> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Mark Lord Cc: linux-ide@vger.kernel.org, Alan Cox Mark Lord wrote: > Malcolm Gillies wrote: >> By swapping around components, I've established that the problem is >> unlikely due to the cable (which is 50cm long 80-wire), hard disk or >> controller. When I swap to another, slower CF card (one that only >> supports PIO rather than MWDMA), the error goes away and the hard disk >> operates happily at UDMA/33. > .. >> ata1.00: CFA: SanDisk SDCFH-1024, HDX 4.07, max MWDMA2 >> ata1.00: 2001888 sectors, multi 0: LBA >> ata1.01: ATA-7: SAMSUNG HD400LD, WQ100-14, max UDMA/100 >> ata1.01: 781422768 sectors, multi 0: LBA48 >> ata1.01: limited to UDMA/33 due to 40-wire cable >> ata1.00: configured for MWDMA2 >> ata1.01: configured for UDMA/33 > .. > The fastest DMA speed reported for the CF is MWDMA2, which is considerably > slower than UDMA/33. When two devices share a cable, normally both must be > limited to the speed of the slower device, which is MWDMA2 in this case. > > Both devices report being capable of 120ns cycle times for DMA, > but UDMA double-clocks those cycles, something that is incompatible > with non-UDMA devices. > > I don't think we can safely assume that UDMA can co-operate with non-UDMA > on the same cable. In this case, it might be causing the CF device to > falsely detect control cycles. The mystery for me is that 1) there are no errors reported for the CF device, only for the UDMA HD 2) the HD runs error-free at UDMA/33 when I use a different, PIO-only CF card but otherwise the same cabling, adaptor etc. In response to Alan's suggestion, the second point suggests it's not a cabling problem. Any suggestions on how to debug this further appreciated. cheers, Malcolm