Re: Seg fault on any FB write (Epson S1D13A04onColdfire running 2.6.25)

[Hinko Kocevar <hinko.kocevar@cetrtapot.si>]

James Kimble wrote:
> 
> In looking at your driver (which I think is a lot better organized than
> the general one that came with the kernel by the way) I see that you're
> doing a whole string of:
> 
>                                            ~~~~~~~~~~
>    device_create_file(&s1d13706fb_device.dev, &dev_attr_reg_0x12);
>    device_create_file(&s1d13706fb_device.dev, &dev_attr_reg_0x14);
>    device_create_file(&s1d13706fb_device.dev, &dev_attr_reg_0x16);
>                                             ~~~~~~~~~~     
> In  s1d13706fb_init(). I didn't do any of this my driver. Is this needed
> for any purpose other than to allow easy access to change the values in
> these registers in user space?
> 

It is there purely for debugging purposes. It also allows quick setup of
eg. different LCD panels that require some tweaking in order to center the
image or fix refresh rate.

> I was able to port your driver to the values and registers used by my
> device and the behavior is virtually the same as with my driver. Screen
> is initialized, I can see the color palette get set and the panel

And if you draw a pixel from the driver - does it work? Another quick test
is to set color palette and then memset() complete framebuffer memory to
a singles value stored in palette, or change the palette index value to
achieve image color change on the screen.

> enable. Everything boots up fine but none of my user space applications
> work. The first time I try to write to a register or video memory I get
> a seg fault.
> 

Does the oops appear in the dmesg, too?

> This has got to be some kind of memory configuration issue. I've moved
> the CS configuration for this device to different memory locations but
> it doesn't change the behavior. I'm setting things up in U-Boot in
> exactly the same way I had been setting them up in Colilo for the 2.6.10
> kernel (where everything worked).
> 

What about other memory mapped devices you might have on the system? Do
they function properly? If not this might be indicator where look for
the problem.

Regards,
Hinko

-- 
Hinko Kočevar, OSS developer
ČETRTA POT, d.o.o.
Planina 3, 4000 Kranj, SI EU
tel     ++386 (0) 4 280 66 03
e-mail  hinko.kocevar@cetrtapot.si
http    www.cetrtapot.si


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