[PATCH] video: imx: assert that image buffer doesn't cross a 4 MiB boundary

Uwe Kleine-König u.kleine-koenig at pengutronix.de
Wed Sep 16 23:10:52 PDT 2015


On Wed, Sep 16, 2015 at 10:00:44PM +0200, Uwe Kleine-König wrote:
> The reference manual (for the i.MX25 in my case) states:
> 	This field must start at a location that enables a complete
> 	picture to be stored in a 4 Mbyte memory boundary (A [21:0]). A
> 	[31:22] has a fixed value for a picture’s image.
> Check this condition for user-supplied framebuffer values and enforce it
> for driver-allocated buffers.

Maybe add here:

If the buffer crosses a 4 MiB boundary the pixels that are "out of
bounds" just appear white on the display.

I didn't check if the counter overflows and than picks up data from 4
MiB below the expected memory, but I would be surprised if I had only
0xff there.

Best regards

Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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