Switching from linux 2.6.29 to 3.4.3

We have a product with an mini2440 based board and deliver since 2 years
with kernel 2.6.29. Our changes to the hardware are reflected in patches
against the 2.6-kernel (only a few things). Now we decided to test
buildroot. Everything works fine with the generated root and the old kernel
(packed in as tar + patches + config) but the kernel makes some trouble:
  a) Baudrate at debug port ttySAC0 is 38400 instead of 115200
     so uboot=115200 -> kernel 38400 -> login 115400.
  b) The display (type1=7") shows up as 800x480 in fbset but
     shows only stripes. The programs dont fail (/dev/fb0 working)
     but no output (blinking stripes)
We tested patchsets from different sources (pengutronix) but in the end we
have no working solution. So my question: Is there a working
patchset+kernel-config for Kernel 3.4?

a) should be soved with a correct kernel command line
b) should be solved with a correct timing adaption in the platform file

a) did you forward a kernel command line which contains
"console=ttySAC0,115200" to setup the baudrate to your requirements?

b) Did you compare the timing settings for your 7" display from your
existing and *working* 2.6.29 and the ones in my 3.4 kernel (in the git
repository) in our Pengutronix board support package?

Thanks,
a) we use a modified u-boot that boots our kernel from /uImage in ext2 on
sd-card and generates also hwaddr in cmdline. We will change there.

b) The timing is a little bit different:
2.9.29:
#define LCD_WIDTH 800                                                      
                                                                           
                                                                           
                                              
#define LCD_HEIGHT 480                                                     
                                                                           
                                                                           
                                              
#define LCD_PIXCLOCK 40000                                                 
                                                                           
                                                                           
                                              
                                                                           
                                                                           
                                                                           
                                              
#define LCD_RIGHT_MARGIN 67                                                
                                                                           
                                                                           
                                              
#define LCD_LEFT_MARGIN 40                                                 
                                                                           
                                                                           
                                              
#define LCD_HSYNC_LEN 31                                                   
                                                                           
                                                                           
                                              
                                                                           
                                                                           
                                                                           
                                              
#define LCD_UPPER_MARGIN 25                                                
                                                                           
                                                                           
                                              
#define LCD_LOWER_MARGIN 5                                                 
                                                                           
                                                                           
                                              
#define LCD_VSYNC_LEN 1

3.4.3:
  _LCD_DECLARE(                                                            
                                                                           
                                                                           
                                
                        10,                     /* the 7" runs slower */   
                                                                           
                                                                           
                                              
                        800, 40, 40, 48,        /* x timing */             
                                                                           
                                                                           
                                              
                        480, 29, 3, 3,          /* y timing */             
                                                                           
                                                                           
                                              
                        50),                    /* refresh rate */         
                                                                           
                                                                           
                                              
                .lcdcon5        = (S3C2410_LCDCON5_FRM565 |                
                                                                           
                                                                           
                                              
                                   S3C2410_LCDCON5_INVVLINE |              
                                                                           
                                                                           
                                              
                                   S3C2410_LCDCON5_INVVFRAME |             
                                                                           
                                                                           
                                              
                                   S3C2410_LCDCON5_PWREN),                 
                                                                           
                                                                           
                                              
        }

this is a bit different

3.4.4:    800 40 40 48  480 29   3   3
2.6.29:  800 67 40 31  480 25   5   1

clock: old 40 Mhz
new: 50 *(480+29+3)*(800+40+40) = 22.528 Mhz

is this a problem?

According to the datasheet
(http://www.friendlyarm.net/dl.php?file=AT070TN83.pdf) the clock speed
should be typical at 33 MHz (up to 50 MHz).
According to the calculation method in the kernel sources the clock speed
results into: (10*100000000000LL) / ((50) * (800 + 40 + 40 + 48) * (480 +
29 + 3 + 3)) = 41,8 MHz

Thats OK - what i missed was the unit (picoseconds) for the clock.
Further investigation showed up: Whenever i use fbset and change something
(like pixclock, vslen...)  nothing changes in the timing but the display
works then. I also get an output with some register values (always the
same) when i change - but not initially. That means some initialization is
missing in the init-code i think.

Peter, please visit our Mini2440 BSP website, there is now a patch
available to make the LCD work again. Also your display should work now
with a 3.4 kernel and the patch stack from our Mini2440 BSP.