[PATCH] ep93xx: add framebuffer support to edb93xx boards

On Saturday, January 08, 2011 12:53 PM, Martin Guy wrote:

On Fri, Jan 7, 2011 at 11:38 PM, H Hartley Sweeten [off-list ref] wrote:

quoted

The ep9307, ep9312, and ep9315 variants of the ep93xx processor include the
raster engine needed for framebuffer support.

This allows the EDB93xx boards with those processors to use the framebuffer
driver.

Tested on an EDB9307A with the following kernel parameters:
? ? ? ?video=640x480-16 at 60
? ? ? ?video=1024x768-16 at 60

Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>

The code looks good, but there are hardware bugs in the EP93XX that
make the screen image jump a few pixels to the right once every few
seconds.  We found that 800x600-16 and 1024x768-8 were the highest
modes that are stable.

Hardware bugs in the EP93XX... No... ;-)

Did you find 1024x768-16 to be stable, say when running X and moving a
window? The effect was most visible on a phosphor CRT, less noticeable
on an LCD.

I don't have any use for X on the EP93XX so, no I have not tested that.
My app uses the SDL library and has very little actual "motion" going on
so the screen looks pretty stable in my tests.

I have noticed some timing issues with the framebuffer driver, the requested
60Hz refresh is being reported as either 59 or 61Hz on the display, but I
haven't taken the time to look into it yet.

Could the problem you are seeing just be a bandwidth limitation?  Have you
tried changing the AHB master priority order with the SysCon BysMstrArb
register (0x8093_0054)?  The default priority (00) has the following order:

1 - Raster Cursor
2 - MAC
3 - USB
4 - DMA
5 - ARM920T
6 - Raster

The other priority's put the Raster first and shuffle the others around
various ways.

Regards,
Hartley