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RE: using cacheable buffer for descriptor

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From: Yang Fei-AFY095 <fei.yang@...>
To: Alan Stern <stern@...>
Cc: <linux-usb@...>, Xiao Richard-a2590c <a2590c@...>, Luan James-WLJL13 <James.Luan@...>
Subject: RE: using cacheable buffer for descriptor
Date: Friday, July 3, 2009 - 6:06 pm

>> 1. I see dma_cache_maint is called by usb_submit_urb before starting 


In drivers/usb/core/hcd.c, usb_hcd_submit_urb -> map_urb_for_dma ->
dma_map_single -> dma_cache_maint.
dma_map_single is defined in arch/arm/include/asm/dma-mapping.h

This is called when we submit urb, for OUT data, I think it's sufficient
for cache consistency. But what I need to know is how we guarantee the
cache consistency for IN data, because the DMA is going to update the
physical memory when receiving data from device, something has to be
done upon completion of the urb.



Regards,
Fei
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Messages in current thread:
using cacheable buffer for descriptor, Yang Fei-AFY095, (Fri Jul 3, 12:43 am)
Re: using cacheable buffer for descriptor, Alan Stern, (Fri Jul 3, 5:16 pm)
RE: using cacheable buffer for descriptor, Yang Fei-AFY095, (Fri Jul 3, 6:06 pm)
RE: using cacheable buffer for descriptor, Alan Stern, (Fri Jul 3, 7:19 pm)
RE: using cacheable buffer for descriptor, Yang Fei-AFY095, (Fri Jul 3, 11:43 pm)
Re: using cacheable buffer for descriptor, Ming Lei, (Sat Jul 4, 5:11 am)
Re: using cacheable buffer for descriptor, Ming Lei, (Sat Jul 4, 11:41 am)
Re: using cacheable buffer for descriptor, Russell King - ARM Linux, (Sat Jul 4, 2:07 pm)
Re: using cacheable buffer for descriptor, Ming Lei, (Sat Jul 4, 10:38 pm)
Re: using cacheable buffer for descriptor, Russell King - ARM Linux, (Sun Jul 5, 2:46 am)
RE: using cacheable buffer for descriptor, Yang Fei-AFY095, (Sat Jul 4, 5:01 pm)
Re: using cacheable buffer for descriptor, Alan Stern, (Sat Jul 4, 11:51 am)