Re: [PATCH 1/8] ARM: OMAP: fix DMA vs memory ordering

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, Apr 20, 2012 at 03:22:33PM -0700, Tony Lindgren wrote:
> * Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> [120418 03:14]:
> > Using coherent DMA memory with the OMAP DMA engine results in
> > unpredictable behaviour due to memory ordering issues; as things stand,
> > there is no guarantee that data written to coherent DMA memory will be
> > visible to the DMA hardware.
> > 
> > This is because the OMAP dma_write() accessor contains no barriers,
> > necessary on ARMv6 and above.  The effect of this can be seen in comments
> > in the OMAP serial driver, which incorrectly talks about cache flushing
> > for the coherent DMA stuff.
> > 
> > Rather than adding barriers to the accessors, add it in the DMA support
> > code just before we enable DMA, and just after we disable DMA.  This
> > avoids having barriers for every DMA register access.
> > 
> > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx>
> 
> Acked-by: Tony Lindgren <tony@xxxxxxxxxxx>

Would you like me to push this upstream on my next -rc push (with a
stable tag?)
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Arm (vger)]     [ARM Kernel]     [ARM MSM]     [Linux Tegra]     [Linux WPAN Networking]     [Linux Wireless Networking]     [Maemo Users]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Trails]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux