[RFC] omap4-fb: use uncached screen_base

Sascha Hauer s.hauer at pengutronix.de
Fri Apr 12 11:03:53 EDT 2013

Hi Jan,

On Thu, Apr 11, 2013 at 01:28:19PM +0200, Jan Weitzel wrote:
> If the buffer is cached the image on the LCD is broken. Only some small
> lines on the last rows. Flushing the cache "repairs" the image.
> Is remap_range the right way to get a non cached buffer?

I think using this is ok for now, at least when the driver is ARM
specific, which the omap fb driver is. We do not have a propert API
for this kind of stuff and I currently have no idea how such an API
would look like.

You should make sure though that pdata->screen->start and the screen
size are page aligned.

> This patch only covers prealloc_screen, not dynamic
> If the buffer is dynamic, is the use of dma_alloc_coherent right?


> Or should
> the buffer remaped again if freed?

ideally it should, at least when the screen is passed via platform data.
Anyway, when you pass it via platform_data then you normally do it to
preserve the screen during kernel start, so I wouldn't free it in this


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