Date: Thu, 21 Jul 2005 08:06:36 -0600 (MDT) From: "M. Warner Losh" <imp@bsdimp.com> To: NKoch@demig.de Cc: freebsd-small@freebsd.org, non_secure@yahoo.com Subject: Re: DMA disable for sandisk CF cards ? Message-ID: <20050721.080636.01051330.imp@bsdimp.com> In-Reply-To: <000201c58dd4$5e114360$4801a8c0@ws-ew-3.W2KDEMIG> References: <20050721.020703.41710119.imp@bsdimp.com> <000201c58dd4$5e114360$4801a8c0@ws-ew-3.W2KDEMIG>
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In message: <000201c58dd4$5e114360$4801a8c0@ws-ew-3.W2KDEMIG> "Norbert Koch" <NKoch@demig.de> writes: : > > May be, I miss the point. Why do you want to disable : > > dma on the cf card, when you can instruct FreeBSD : > > to just not use dma (atacontrol(8)) ? : > : > Because newer CF cards, like the SanDisk, negotiate DMA with the : > controller. However, most of the IDE <-> CF Adapters aren't properly : > wired for this, as they only implement CF 1.5 and not CF 2.0. So, : > when FreeBSD goes to access the device, you get all kinds of timeout : > errors. If you are lucky, ata will failback to PIO mode. Most of the : > time it has bitten me, I've not been lucky :-(. : > : > hw.ata.ata_dma=0 is the magic. You can set it at the boot loader : > prompt, or you can add it to /boot/loader.conf. atacontrol is way too : > late, since this disabling must be done prior to geom's scan for root : > (or the moral equivalent in 4.x). : : Ok, I understand. But you can't do that selectively on a per-device basis, : can you? There may be something you can do with atacontrol after boot. I've never needed it. Warner
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