Re: [PATCH v2 2/2] Documentation: dmaengine: Add a documentation for the dma controller API

[Maxime Ripard]

Hi Laurent,

Just getting back on something...

On Mon, Oct 06, 2014 at 03:09:48PM +0300, Laurent Pinchart wrote:
> > +   * device_prep_dma_*
> > +     - These functions are matching the capabilities you registered
> > +       previously.
> > +     - These functions all take the buffer or the scatterlist relevant
> > +       for the transfer being prepared, and should create a hardware
> > +       descriptor or a list of descriptors from it
> > +     - These functions can be called from an interrupt context
> > +     - Any allocation you might do should be using the GFP_NOWAIT
> > +       flag, in order not to potentially sleep, but without depleting
> > +       the emergency pool either.
> 
> You could add "Drivers should try to preallocate the data structures they 
> require to prepare a transfer."

Isn't that obvious?

I mean, if we're in this function, we're already preparing a
transfer... And I would expect any programmer that followed CS101 to
be able to allocate the memory it needs :)

The rest of the issues have been fixed, thanks!
Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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