hi alessandro,
El Fri, Feb 12, 2010 at 10:23:58AM +0100 Matthias Kaehlcke ha dit:
El Fri, Feb 12, 2010 at 08:01:26AM +0100 Alessandro Rubini ha dit:
i gave my ack after a visual review of the patch, without having tested it. i just installed a patched u-boot on one of my boards and it doesn't boot :(
Oh. The opposite of my board.
Then, since I don't have a 9315A but only a similar one, it's better to drop the patch. I'll have a different sdram_cfg file for mine, then.
i'm pretty sure we'll be able to track this down, the purpose of your patch is correct, i actually wonder why the current code works ...
if we can't solve the issue in the next days, you could still send a patch which only writes the GlConfig register in program_mode_registers(). this would fix at least on of the issues and make your code less different from the one in the tree
maybe i have found a clue: i think the original assembly code wasn't correct either. the comment talks about reading from each bank, but then code like this is excuted:
ldr r0, =0x00000000 /* A[22:21] = b00 */ str r0, [r0]
which *writes* to the bank, but doesn't read from it.
according to the errata note a bank is precharged by reading from it. the current code does this, but before the bank is configured properly. i suspect that is the cause for the hang i see on my boards. i've put together some code which does the precharge after setting up the mode registers. on my boards based on the edb9301 and edb9307a design u-boot boots with this code.
below you find a patch, could you give it a try on your board, when you find some time and feel well enough?
thanks
Matthias
---
diff --git a/board/edb93xx/sdram_cfg.c b/board/edb93xx/sdram_cfg.c index 6155f0e..f3db750 100644 --- a/board/edb93xx/sdram_cfg.c +++ b/board/edb93xx/sdram_cfg.c @@ -47,25 +47,27 @@ void sdram_cfg(void)
early_udelay(200);
- force_precharge(); + /* + * Errata of most EP93xx revisions say that PRECHARGE ALL isn't always + * issued, so we omit it at this point. Instead we force a precharge + * after having programmed the mode registers + */
setup_refresh_timer();
program_mode_registers();
- /* Select normal operation mode */ - writel(GLCONFIG_CKE, &sdram->glconfig); + force_precharge(); }
static void force_precharge(void) { - /* - * Errata most EP93xx revisions say that PRECHARGE ALL isn't always - * issued. - * - * Do a read from each bank to make sure they're precharged - */ + struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE; + + /* Select normal operation mode */ + writel(GLCONFIG_CKE, &sdram->glconfig);
+ /* Do a read from each bank to make sure they're precharged */ PRECHARGE_BANK(0); PRECHARGE_BANK(1); PRECHARGE_BANK(2); @@ -101,6 +103,11 @@ static void setup_refresh_timer(void)
static void program_mode_registers(void) { + struct sdram_regs *sdram = (struct sdram_regs *)SDRAM_BASE; + + /* Select mode register update mode */ + writel(GLCONFIG_MRS | GLCONFIG_CKE, &sdram->glconfig); + /* * The mode registers are programmed by performing a read from each * SDRAM bank. The value of the address that is read defines the value