I'm interested in how this discussion pans out. I have encountered this problem (with flinfo) with my MPC8641HPCN. The patch presented by Zhang Wei (and other freescale employees) does seem to allieviate the problem when I compile u-boot with ELDK 4.0.
However, some scenarios here worry me: -- with the patch, compiled with ELDK 4.0 is peachy. -- without the patch, compiled with ELDK 4.0 FAILS. -- without the patch, compiled with ELDK 3.1.1 is peachy.
At the time of my testing (early this week) I was using a git tree about 2 weeks old from jdl.com, which is what the freescale folks seem to be using at the moment. It worries me that changing a compiler version could affect this bug, but I guess I've seen stranger things.
Could this be a subtle timing problem with the processor? Could it be a timing problem with the flash? Am I nuts? :P
Merry Christmas! Chris
On Fri, 2006-12-22 at 15:11 +0100, Wolfgang Denk wrote:
In message 458BBB5D.1030005@freescale.com you wrote:
After perform flash_read_jedec_ids(), the cfi query read will get an '0xff'. From this flash's specification, the read for flash commands in 16bit port connection should perform 16bit read and ignore the high 8bit data. Although this issue maybe occurs in the special chip, perform the fully 16bit read is a safety operation.
But your patch does NOT perform a 16 bit read. It calls memcpy(); the default implementation of memcpy [see lib_generic/string.c] does this:
char *tmp = (char *) dest, *s = (char *) src;
while (count--) *tmp++ = *s++;
i. e. it performs a character copy, too, so it makes no difference compared to the original code.
The modification refers to the cfi flash drivers in Linux kernel (The cfi_read_query() function in include/linux/mtd/cfi.h file). It's more easy and clear than making the different type date read for different portwidth (such as ushort_read() for x16, ulong_read() for x32).
I understand your intentions, but your patch does not do what you think it does, so if it really fixes the problem on your system there must be another cause or effect.
Best regards,
Wolfgang Denk