Re: iMX35 3stack framebuffer problem

[Baruch Siach <baruch@tkos.co.il>]

Hi Boaz,

On Sun, May 29, 2011 at 09:08:58AM +0300, Boaz Ben-David wrote:
> Revisiting the issue below, it there a convinient way
> to use the FB in barebox without creating a flicker on the LCD in
> the transition from Barebox to the kernel?

Probably not, at the moment.

One big problem (not the only one) is that the mx3fb driver uses DMA to 
transfer the display image from the system RAM to the LCD. The ARM booting 
document, however, requires the bootloader to "quiesce all DMA capable 
devices" (Documentation/arm/Booting).

The best you can achieve (assuming you have designed your hardware correctly) 
is to blank your LCD using a GPIO just before booting the kernel, and then 
switch this GPIO again just after painting your logo from the newly boot 
kernel.

baruch

> On 03/08/11 09:10, Baruch Siach wrote:
> >Hi Boaz,
> >
> >On Tue, Mar 08, 2011 at 09:03:55AM +0200, Boaz Ben-David wrote:
> >>Yes, I am using the freescale kernel unfotunately.
> >>Do you know of some way to fix this (a patch for the freescale kernel
> >>maybe)?
> >A simple way to check whether this is the problems is to just disable the
> >framebuffer in the kernel build, and make sure that you can boot again.
> >
> >Then, the fix for this problem is to move the request_irq() call to the end of
> >the .probe routine.
> >
> >You should not expect any kind of support from Freescale for their released
> >Linux kernels.
> >
> >baruch
> >
> >>On Tue, 2011-03-08 at 16:35 +1100, Marc Reilly wrote:
> >>>On Tuesday, March 08, 2011 03:35:10 am Boaz Ben-David wrote:
> >>>>Hi,
> >>>>
> >>>>When using the iMX35 freescale 3stack we are having some issues with the FB
> >>>>driver. On device boot we enable the fb using "fb0.enable=1" and then try
> >>>>to boot the kernel from nand. The problem is that after the kernel is
> >>>>loaded to RAM and extracted the board hangs. If we do not init the fb0
> >>>>device but simply boot the kernel it works fine. Trying "fb0.enable=0"
> >>>>before booting also did not help.
> >>>>Did anyone encounter this issue yet or are we doing something wrong?
> >>>Are you using the freescale kernel? It doesn't handle loading the IPU driver
> >>>if the IPU has been enabled previously.. (an IRQ fires before all the driver
> >>>structures have been initialized and crashes)
> >>>
> >>>Cheers,
> >>>Marc

-- 
                                                     ~. .~   Tk Open Systems
=}------------------------------------------------ooO--U--Ooo------------{=
   - baruch@tkos.co.il - tel: +972.2.679.5364, http://www.tkos.co.il -

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