rockbox

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Marcin Bukat 17db971b66 rk27xx: leave the SDRAM mode and timings as the boot left them Firmware builds reprogram the SDRAM controller twice. system_init() sets burst 8, T_RP = T_RCD = 1 and the refresh, with CAS 3 since `a6538abd16` - CAS 2 on HM60X/HM801. And set_sdram_timing(), on every CPU frequency change, rewrites the mode: CAS 2 whenever the AHB runs at 100 MHz or below, which is every clock this code sets. On a generic rk2705 the firmware hangs in system_init() on those writes; with them skipped it boots. Doing the same writes from IRAM, so that nothing touches the SDRAM while the controller reprograms the chip, hangs the same way: it is the settings themselves. The board's SDRAM is an Elpida EDS1216AATA-75 (16 MB), a 133 MHz part at CAS 3 whose minimum clock period at CAS 2 is 10 ns - exactly the 100 MHz it runs at here, with no margin, next to minimal T_RP/T_RCD. On a Samsung YP-CP3 the firmware boots but corrupts memory at random once the clock first changes: data aborts on valid addresses in unrelated code, undefined instruction exceptions on valid instructions, glitches in the boot logo, crashes on USB plug and unplug. A memory test over 15 MB passes with the boot's setup (CAS 3, burst 1, T_RP = T_RCD = 2) and with system_init()'s values alike - it never changes the clock - and skipping only the system_init() writes is not enough, as set_sdram_timing() still selects CAS 2. With both removed the YP-CP3 runs, passes a USB mass storage stress test and survives USB unplug. The boot ROM's and the bootloaders' setup works on every rk27xx target seen, and nothing before Rockbox changes it (the NAND bootloader's stage 1 and rk27load's s1 only probe the organisation). The gain claimed for the tweak was a slight improvement in memory throughput. So remove it for every rk27xx target, the HM60X/HM801 CAS 2 included, and have set_sdram_timing() adjust only the refresh to the bus clock. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Change-Id: Icd063367783b0ae6eb80bad67d908269c07e704f		2026-10-01 20:18:10 +02:00
android	chore: Get rid of all vestigal CVS '$Id:$' tags	2026-06-01 16:01:18 -04:00
apps	jpeg_load: decode chroma sampled like 1x2 or 2x1 luma	2026-10-01 13:47:38 -04:00
backdrops	ap80max: New hosted port	2026-08-13 17:55:06 -07:00
bootloader	h1x0/h3x0: Get rid of redundant cut-down bidi_l2v() function	2026-09-29 10:16:26 -04:00
docs	firmware: limit system_memory_guard() to coldfire targets	2026-09-23 13:12:48 -04:00
firmware	rk27xx: leave the SDRAM mode and timings as the boot left them	2026-10-01 20:18:10 +02:00
fonts	chore: Get rid of all vestigal CVS '$Id:$' tags	2026-06-01 16:01:18 -04:00
icons	chore: Get rid of all vestigal CVS '$Id:$' tags	2026-06-01 16:01:18 -04:00
lib	opus: filter the PLC excitation in place	2026-09-30 11:25:30 -04:00
manual	manual: Fix case of "iPod"	2026-09-30 07:58:19 -04:00
packaging	3ds: Port refactor.	2026-09-01 08:39:07 -04:00
tools	imx233: re-enable utf8proc and associated functionality.	2026-09-29 22:39:49 -04:00
uisimulator	Add "rbfs" prefix to native filesystem functions	2026-09-17 16:22:31 -04:00
utils	misc: forums.rockbox.org -> www.rockbox.org/forums	2026-09-27 10:46:01 -04:00
wps	ap80max: New hosted port	2026-08-13 17:55:06 -07:00
.gitattributes	Add a gitattributes file for the migration.	2011-12-01 14:14:59 +00:00
.gitignore	misc: Update gitignore to cover a bunch of utils/* binaries	2026-06-17 13:56:29 -04:00
.gitreview	misc: Add a .gitreview file for better gerrit integration	2021-06-24 07:22:19 -04:00

docs/README

               __________               __   ___.
     Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
     Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
     Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
     Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
                       \/            \/     \/    \/            \/

Build Your Own Rockbox

1. Clone 'rockbox' from git (or extract a downloaded archive).

   $ git clone git://git.rockbox.org/rockbox

     or

   $ tar xJf rockbox.tar.xz

2. Create a build directory, preferably in the same directory as the firmware/
   and apps/ directories. This is where all generated files will be written.

   $ cd rockbox
   $ mkdir build
   $ cd build

3. Make sure you have mips/m68k/arm-elf-gcc and siblings in the PATH. Make sure
   that you have 'perl' in your PATH too. Your gcc cross compiler needs to be
   a particular version depending on what player you are compiling for. These
   can be generated using the rockboxdev.sh script in the /tools/ folder of the
   source.

   $ which arm-elf-eabi-gcc
   $ which perl

4. In your build directory, run the 'tools/configure' script and enter what
   target you want to build for and if you want a debug version or not (and a
   few more questions). It'll prompt you. The debug version is for making a
   gdb version out of it. It is only useful if you run gdb towards your target
   Archos.

   $ ../tools/configure

5. *ploink*. Now you have got a Makefile generated for you.

6. Run 'make' and soon the necessary pieces from the firmware and the apps
   directories have been compiled, linked and scrambled for you.

   $ make
   $ make zip

7. unzip the rockbox.zip on your music player, reboot it and
   *smile*.

If you want to build for more than one target, just create several build
directories and create a setup for each target:

   $ mkdir build-fuzeplus
   $ cd build-fuzeplus
   $ ../tools/configure

   $ mkdir build-xduoox3
   $ cd build-xduoox3
   $ ../tools/configure

Questions anyone? Ask on the mailing list or on IRC. We'll be happy to help you!