[U-Boot] [PATCH v2 1/2] usb: align buffers at cacheline

Marek Vasut marex at denx.de
Wed Feb 29 22:38:58 CET 2012


> Hi Marek,
> IMO, Simon has already mentioned the reason of using
> ALLOC_CACHE_ALIGN_BUFFER,
> Please find below my explanation about other doubts.
> 
> On Monday 27 February 2012 10:19 PM, Marek Vasut wrote:
> >> As DMA expects the buffers to be equal and larger then
> >> cache lines, This aligns buffers at cacheline.
> >> 
> >> Signed-off-by: Puneet Saxena<puneets at nvidia.com>
> >> Signed-off-by: Jim Lin<jilin at nvidia.com>
> >> ---
> > 
> > First of all, thanks for this patch, it really helps. But, there are a
> > few things that concern me.
> > 
> >> Changes for V2:
> >>      - Use "ARCH_DMA_MINALIGN" directly
> >>      - Use "ALIGN" to align size as cacheline
> >>      - Removed headers from usb.h
> >>      - Send 8 bytes of device descriptor size to read
> >>      
> >>        Max packet size
> >> 
> >> scsi.h header is needed to avoid extra memcpy from local buffer
> >> to global buffer.
> >> 
> >>   common/cmd_usb.c            |    3 +-
> >>   common/usb.c                |   61
> >> 
> >> ++++++++++++++++++++++++------------------ common/usb_storage.c        |
> >> 59 +++++++++++++++++++---------------------- disk/part_dos.c            
> >> |
> >> 
> >>     2 +-
> >>   
> >>   drivers/usb/host/ehci-hcd.c |    8 +++++
> >>   include/scsi.h              |    4 ++-
> >>   6 files changed, 77 insertions(+), 60 deletions(-)
> >> 
> >> diff --git a/common/cmd_usb.c b/common/cmd_usb.c

I see, thanks for explaining!

M


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