[U-Boot] Add video support for mx51evk

[Anatolij Gustschin]

Hi,

On Tue, 02 Nov 2010 07:40:04 +0100
Stefano Babic <sbabic at denx.de> wrote:
...
> > There is also a second issue where I would like to know your thoughts. Very
> > early on system initialization, when LCD is enabled, there is a call to
> > "lcd_setmem" from board.c. By that time, the video variables,
> > "panel_info", are
> > not set yet. Thus U-Boot doesn't reserve the appropriate amount of
> > memory for
> > the display. I was going to set "panel_info" variable on mx51evk.c, but
> > I would like to know how you solved it for vision2 first. 
> 
> Thanks for pointing out, I have already seen the point, but at the end I
> forget to fix it ;-). Probably because there is no side-effects on this
> board, but this does not mean that the issue should not fixed for
> vision2, too.
> 
> The problem arises from the fact that the setup of the display
> parameters was static and everything was solved at compile time. With
> the framebuffer for the MX51, I needed the possibility to change
> dinamically the parameters, because the board can have different LCD
> displays.
> 
> Consider this, I do not think the actual computation in lcd_setmem() is
> correct. We need to compute the maximum amount of memory to be reserved
> to the framebuffer, not the value requested by the current display
> interface. We could add a CONFIG_SYS_VIDEO_SIZE that contains the
> maximum amount of memory needed, because the value is strictly
> board-dependent, and change lcd_setmem to use it. Anatolij, what do you
> think about this ?

We should reserve the amount of memory we actually need for the
used display configuration, I think. Reserving the maximum amount
would be needed if we have to support switching the display
resolution at runtime, but I don't think that this is needed in
your case. Therefore I prefer the solution that reserves the
actually needed amount of memory.

Best regards,
Anatolij