Re: [U-Boot] [PATCHv2 CFI flash]: Workaround for Numonyx Axcell P33/P30 256-Mbit 65nm bug

Hi Stefan,

On Tue, Aug 10, 2010 at 01:20:42PM +0200, Stefan Roese wrote:

Hi Philippe,

On Monday 09 August 2010 17:46:03 Philippe De Muyter wrote:

...

...

Please move this variable declaration of "cmd" and assignment further down (see below). You can remove the "{" "}" of this block then.

Here is the excerpt from the errata :

Workaround: If the interval between 60h and its subsequent command can be guaranteed within 20μs, Option I is recommended, otherwise Option II (involves hardware) should be selected. Option I: The table below lists the detail command sequences: Command Data bus Address bus Remarks Sequence 1 90h Block Address Read Lock Status 2 Read Block Address + 02h (2)(3) (1) 3 60h Block Address (2)(3) (1) Lock/Unlock/RCR Configuration 4 D0h/01h/03h Block Address Notes: (1) Block Address refers to RCR configuration data only when the 60h command sequence is used to set RCR register combined with 03h subsequent command. (2) For the third and fourth command sequences, the Block Address must be the same. (3) The interval between 60h command and its subsequent D0h/01h/2Fh/03h commands should be less than 20μs.

Because of requirement (3), I choosed to minimize the number of instructions between the `read lock status' and the `unlock' commands, hence the initialisation of `cmd' moved before the `read lock status' (hidden in `flash_isequal').

Yes, you're right. I had misread the doc :(

From my understanding, "only" the last 2 operations need to be in max. 20µs interval. If this is the case, then I would prefer this code version:

I prefer it too.

case CFI_CMDSET_INTEL_EXTENDED:
	/*
	 * see errata called
	 * "Numonyx Axcell P33/P30 Specification Update" :)
	 */
	flash_write_cmd (info, sector, 0, FLASH_CMD_READ_ID);
	if (!flash_isequal (info, sector, FLASH_OFFSET_PROTECT,
			    prot)) {
		int flag = disable_interrupts ();
		unsigned short cmd;

		if (prot)
			cmd = FLASH_CMD_PROTECT_SET;
		else
			cmd = FLASH_CMD_PROTECT_CLEAR;

		/*
		 * cmd must come before FLASH_CMD_PROTECT + 20us
		 * Disable interrupts which might cause a timeout here.
		 */

Should the above comment not stay closer to the disable_interrupts () call ?

		flash_write_cmd (info, sector, 0,
				  FLASH_CMD_PROTECT);
		flash_write_cmd (info, sector, 0, cmd);
		/* re-enable interrupts if necessary */
		if (flag)
			enable_interrupts ();
	}

...

...

...

•                   /*
  

•                    * see errata called
  

•                    * "Numonyx Axcell P33/P30 Specification
  

Update" :) + */

•                   flash_write_cmd (info, sector, 0,
  

FLASH_CMD_READ_ID); + if (!flash_isequal (info, sector, FLASH_OFFSET_PROTECT, + prot)) {

•                           int flag = disable_interrupts ();
  

Declare and assign "cmd" here please.

Please change and resubmit. Thanks.

If you still prefer it changed, speak :)

Yes, please let me know if this patch version also fixes the bug. If this is the case, I would prefer that you change it accordingly.

I surmise it does, but I currently do not have a board to test. I'll get new boards (with the same bug) soon, and I'll let you know then.

Best regards

Philippe