Messages in this thread | | | Date | Fri, 17 Dec 2010 14:44:29 -0800 | From | rmorell@nvidia ... | Subject | Re: [RFC] Align tegra-ehci DMA transfers to 32B |
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On Fri, Dec 17, 2010 at 02:32:27PM -0800, Greg KH wrote: > On Fri, Dec 17, 2010 at 01:58:47PM -0800, Robert Morell wrote: > > This small set of patches fixes an issue where DMA from the tegra EHCI > > controller could be corrupted. It was most commonly seen with USB network > > adapters, though in theory it could happen with any USB traffic. > > > > (Note: An attempt was made to fix this with commit 367c3aab, which set > > NET_IP_ALIGN to 0 and NET_SKB_PAD to 32. Unfortunately, not all network > > drivers honor them (presumably since these are intended as optimizations rather > > than hard rules). This does mean that properly-written network drivers should > > fall through this code with very little overhead, however.) > > We don't have many USB network drivers, why not just fix them up to > handle this properly, then you will not need to change any core USB > code, right?
The USB core code is used by devices other than USB adapters. We've only seen this problem so far with usbnet devices, but I can't test every USB device ever to make sure that they always align their DMA to 32 bytes.
Thanks, Robert
> thanks, > > greg k-h >
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