svn commit: r196380 - head/sys/dev/usb

Rafal Jaworowski raj at
Wed Aug 19 15:55:51 UTC 2009

On 2009-08-19, at 17:30, Sam Leffler wrote:

> Rafal Jaworowski wrote:
>> Author: raj
>> Date: Wed Aug 19 14:39:08 2009
>> New Revision: 196380
>> URL:
>> Log:
>>  Fix USB cache sync operations for platforms with non-coherent DMA.
>>    - usb_pc_cpu_invalidate() is called between [consecutive] reads  
>> from a device,
>>    so a sequence of BUS_DMASYNC_POSTREAD and _PREREAD should be  
>> used. Note we
>>    cannot use or'ed shorthand ( _POSTREAD | _PREREAD) for  
>> BUS_DMASYNC flags, as
>>    the low level bus dma sync operation is implementation dependent  
>> and we
>>    cannot assume the required order of operations to be guaranteed.
>>    - usb_pc_cpu_flush() is called before writing to a device, so
>>    BUS_DMASYNC_PREWRITE should be used.
>>    Submitted by:	Grzegorz Bernacki
>>  Reviewed by:	HPS, arm@, usb@ ML
>>  Tested by:	HPS, Mike Tancsa
>>  Approved by:	re (kib)
>>  Obtained from:	Semihalf
> Is this different from the patch I tested on Gateworks 2358 boards  
> which didn't completely resolve problems?

Hm, not sure what patch you have tested with GW. There was an initial  
workaround for this problem from late June time frame, and this commit  
is a refined fix identical to the patch posted 05 Aug to arm at . There  
were other ARM patches in the meantime involving cache sync, but they  
were pmap-related.


More information about the svn-src-all mailing list