FS#11911 - issues with nano 2g display

Attached to Project: Rockbox
Opened by Andree Buschmann (Buschel) - Friday, 28 January 2011, 07:00 GMT
Last edited by Andree Buschmann (Buschel) - Friday, 22 April 2011, 20:42 GMT
Task Type Bugs
Category Drivers
Status Closed
Assigned To No-one
Operating System iPod Nano 2G
Severity High
Priority Normal
Reported Version Release 3.7.1
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


As reported in,27098.0.html there were issues with the nano 2g LCD reported (see Forum thread or attachment for a photo).

The following information has been collected so far:

working -> r25375-100328
non-working -> current (something after the latest speed optimizations)

LCD type
From diagmode it shows:
LCD Detect0:1
LCD Detect1:0

Also in hardware debug:
type: 1, (7) LDS176
This task depends upon

Closed by  Andree Buschmann (Buschel)
Friday, 22 April 2011, 20:42 GMT
Reason for closing:  Fixed
Additional comments about closing:  Fixed with r29764.
Comment by Michael Sevakis (MikeS) - Thursday, 10 March 2011, 20:54 GMT
I took a quick look in there out of curiosity and I found it odd that it does no clipping of drawing parameters.
Comment by Andree Buschmann (Buschel) - Friday, 11 March 2011, 07:03 GMT
Michael, can you explain in more detail what you found in the code?
Another hint might be  FS#11997 . As the above image shows a working status bar I am not covinced that this is a driver issue. Maybe it is an effect of viewports?
Comment by Michael Sevakis (MikeS) - Sunday, 13 March 2011, 08:12 GMT
Just that really. I don't know the code very well but other drivers clip and out of range parameters would cause bad register values as well as invalid framebuffer addresses. My own initial strategy would be to just put some clipping code in there and see since code assumes the driver will clip the screen updates. If that didn't solve the problem, I'd still leave the clipping code there since then you know that won't be a continuing possibility and keep trying whatever came to mind.
Comment by Andree Buschmann (Buschel) - Friday, 22 April 2011, 20:42 GMT
Two more reports:,27777.0.html,27813.0.html

The issue could be reproduced and the underlying cause was identified as insufficient voltage supply of the LCD. A voltage supply of 2.8V was tested and verified to be sufficient for one of the users with a problematic iPod nano 2G.

The change which lowered the voltage supply from 3.0V (Apple OF) to 2.6V (svn before r29764) was submitted to get rid of a buzz noise that the LCD is generating. With the new 2.8V setting this buzz is still significantly lower as with Apple OF.