touchscreen: edt-ft5x06: Prevent DMA driver from mapping an area on stack

[maitysanchayan at gmail.com]

Hello,

On 15-12-12 20:42:37, Dmitry Torokhov wrote:
> On Sat, Dec 12, 2015 at 06:13:55PM +0100, Wolfram Sang wrote:
> > 
> > > Frankly speaking I do not know where the fix should actually be. I2C IMX
> > > driver somehow taking care of this or the users of I2C, touchscreen drivers
> > > in this case. In my opinion, the fix should be with the touchscreen driver
> > > however I did like to have feedback or hear opinions on what is the accepted
> > > solution to this.
> > 
> > There is no accepted solution to this yet :( DMA is/was still too rare for
> > a serious discussion about this. There is also [1] and probably more...
> > 
> > [1]  http://patchwork.ozlabs.org/patch/220137/
> 
> I believe vast majority of i2c client drivers do not expect that the
> transfer buffer they supply in i2c messages are supposed to be DMAable
> (unlike USB and SPI buses that had that requirement from the beginning).
> 
> I won't be applying this patch unless we decide that I2C changes the
> rules.

Understood. Thanks for the clarifications Dmitry and Wolfram.

- Sanchayan.