RE: [Ltib] Re: LPC3250 board, X server fault: Invalid argument

[Daniel Widyanto]

Hi Dmitry,

Quote:
k = ioctl (priv->fd, FBIOPUT_VSCREENINFO, &var);

if (k < 0)
{
    fprintf (stderr, "error: %s\n", strerror (errno));
    return FALSE;
}

means:
Call FBIOPUT_VSCREENINFO service from framebuffer driver (or any driver that's 
pointed by priv->fd). The arguments that the service needs (and/or the output 
of the service) are put in 'var'. But the frame buffer driver said that the 
'var' argument was invalid. Hence, it returned k < 0. 

I think the frame buffer FBIOPUT_VSCREENINFO service has changed their 
parameters (function signature) since the last X-server include them.

Since you've known your 'var' structure, you can search for frame buffer's 
IOCTL function inside the kernel and match the argument signature of 
FBIOPUT_VSCREENINFO with 'var' signature.

Happy hunting =)

Cheers,
-daniel

-----Original Message-----
From: address@hidden [mailto:address@hidden On Behalf Of Dmitry Vinokurov
Sent: Thursday, August 06, 2009 6:24 PM
To: address@hidden
Subject: [Ltib] Re: LPC3250 board, X server fault: Invalid argument

Some news again.

Executing 'Xfbdev -nolisten tcp -ac -mouse mouse -keybd keyboard' 
results in:
===
Warning: mode not found, using default
error: Invalid argument

Fatal server error:
no screens found
===

If mode is set (as Daniel advised), 'Xfbdev -nolisten tcp -ac -mouse 
mouse -keybd keyboard -screen 320x240x18' (where 18 (6 for each R,G,B) 
is depth for my display, according to documentation) results in:
===
error: Invalid argument

Fatal server error:
no screens found
===

Settings resolution to 240x320 or something other lead to mode not found 
warning.

I've digged a little in the source and found function throwing an error 
-- it is fbdevScreenInitialize. Here is fragment of this function, 
containing error (as I think):
===
if (k < 0 || (t->horizontal != var.xres || t->vertical != var.yres))
    fbdevConvertMonitorTiming (t, &var);

var.activate = FB_ACTIVATE_NOW;
var.bits_per_pixel = screen->fb[0].depth;
var.nonstd = 0;
var.grayscale = 0;

k = ioctl (priv->fd, FBIOPUT_VSCREENINFO, &var);

if (k < 0)
{
    fprintf (stderr, "error: %s\n", strerror (errno));
    return FALSE;
}
===

I think error is here because before this code 'struct fb_var_screeninfo 
var' was initialized using 'k = ioctl (priv->fd, FBIOGET_VSCREENINFO, 
&var);' and all changes of 'var' structure is located exactly in this 
code. By the way, 'fbdevConvertMonitorTiming' executes because var.xres 
= 240 but t->horizontal = 320 and var.yres = 320 but t->vertical = 240

Adding 'fprintf(stderr, "%dx%dx%d\n", var.xres, var.yres, 
var.bits_per_pixel);' before 'k = ioctl (priv->fd, FBIOPUT_VSCREENINFO, 
&var);' give '320x240x18'.

Have anybody ideas about this error? I've completely stuck at this point.

--
Best Regards, 
Dmitry Vinokurov 
<address@hidden>