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Fix USB cache sync operations for platforms with non-coherent DMA.

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- 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
This commit is contained in:
Rafal Jaworowski 2009-08-19 14:39:08 +00:00
parent 6c813c1ccc
commit 35d01728c6
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=196380
1 changed files with 3 additions and 4 deletions
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7
sys/dev/usb/usb_busdma.c
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@ -679,8 +679,8 @@ usb_pc_cpu_invalidate(struct usb_page_cache *pc)
/* nothing has been loaded into this page cache! */
return;
}
bus_dmamap_sync(pc->tag, pc->map,
BUS_DMASYNC_POSTWRITE | BUS_DMASYNC_POSTREAD);
bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_POSTREAD);
bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_PREREAD);
}
/*------------------------------------------------------------------------*
@ -693,8 +693,7 @@ usb_pc_cpu_flush(struct usb_page_cache *pc)
/* nothing has been loaded into this page cache! */
return;
}
bus_dmamap_sync(pc->tag, pc->map,
BUS_DMASYNC_PREWRITE | BUS_DMASYNC_PREREAD);
bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_PREWRITE);
}
/*------------------------------------------------------------------------*