FS#12255 - sansa clipzip: dualboot code for review

Attached to Project: Rockbox
Opened by Bertrik Sikken (bertrik) - Friday, 02 September 2011, 18:36 GMT
Last edited by Bertrik Sikken (bertrik) - Saturday, 29 October 2011, 18:30 GMT
Task Type Patches
Category Bootloader
Status Closed
Assigned To No-one
Operating System Sansa AMSv2
Severity Low
Priority Normal
Reported Version Release 3.9
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No


In anticipation of the new sandisk sansa clip zip players, this is a proposal for the dualboot part of the bootloader.

I propose three steps:
1) Use the same kind of dualboot as for all other AMSv2 players, but make it always boot to the OF. This step proves that our dualboot mechanism with decompression works at all
2) Detect if a specific button is pressed and add a boot delay if it is pressed. This step proves whether we can read a button reliably. I chose the button on GPIO A6 (my guess is that it's one of the volume buttons), because this is a button that is read out directly in the OF and does not rely on key matrixing. If the button readout turns out to not work reliably, the firmware still boots to the OF.
3) Implement the full dualboot code, with the button press deciding between booting either the OF or the rockbox bootloader.

Please comment and/or give suggestions for improvement.

One thing I worry about a bit in the current dualboot code, is the lack of instructions to switch the GPIO pins to the GPIO function and to switch them as GPIO input.
This task depends upon

Closed by  Bertrik Sikken (bertrik)
Saturday, 29 October 2011, 18:30 GMT
Reason for closing:  Accepted