[PATCH 3/4] fsldma: remove DMA_SLAVE support
Ira W. Snyder
iws at ovro.caltech.edu
Thu Sep 30 08:19:31 EST 2010
On Wed, Sep 29, 2010 at 02:52:16PM -0700, Dan Williams wrote:
> On Mon, Sep 27, 2010 at 3:57 PM, Ira W. Snyder <iws at ovro.caltech.edu> wrote:
> > Now that the generic DMAEngine API has support for scatterlist to
> > scatterlist copying, this implementation of the DMA_SLAVE API is no
> > longer necessary.
> > In order to let device_control() continue to function, a stub
> > device_prep_slave_sg() function is provided. This allows custom device
> > configuration, such as enabling external control.
> > + case DMA_SLAVE_CONFIG:
> > +
> > + cfg = (struct fsldma_slave_config *)arg;
> Now that I actually see someone trying to use the recommended
> extension model it comes across as unsafe, what guarantees that arg is
> pointing to a fsldma_slave_config. At at minimum you could ensure
> that this channel has been claimed for private usage which loosely
> implies that the client knows that it is talking to an fsldma channel.
> Even safer is to just assign you a one-off dma_ctrl_cmd
> (FSLDMA_EXTERNAL_START) for this purpose. Otherwise this and the
> other patches look good.
I agree, it is a very unsafe model.
I'll take your suggestion, and do that instead. A new patch will be
More information about the Linuxppc-dev