RFC: arm pcm043 1315.6 IM950 timing (Numonyx Axcell Errata)

[Teresa Gamez]

Hello Tim,

Am Dienstag, den 23.08.2011, 16:40 +0200 schrieb Tim Sander:
> Hi Teresa
> > I'm right now working on updating the pcm043 barebox to work with
> > new hardware revisions. Including updates for NOR Flash support.
> These are good news. 
> 
> > I have also made a patch quite similar to yours. This problem seems
> > to occur only with NOR Flashes having a date code around 39/2010 and
> > earlier. It took me some time to find a module which does have this
> > problem (I just got it today and have not checked it yet).
> > On newer NOR Flashes I could not see any affect/advantage with this
> > workaround. I'll test your patch with this module.
> It seems as if we got such a version. I can write partitions with tftp via 
> network but i can't do a saveenv even with my patch. So i guess its not
> working as i hoped for. I guess since saveenv does an unprotect copy protect
> itself it triggers the errata for these nor chips:
> cfi_protect: unprotect 0xa0040000 (size 131072)
> Flash buffer write error at address a0040000
> Command Sequence Error.
> cfi_protect: protect 0xa0040000 (size 131072)

If only saving the environment makes you trouble it looks more like
the problem of missing support for u32 commands.
As far as I understand this, the buffer size of the NOR flashes where
highly increased. 8bit for the size of data that can be written to the
buffer is not enough. Since tftp sends the data in smaller packages,
writing still works when flashing kernel/rootfs. But fails when saving
the environment.  

> 
> > But adding this workaround will not be enough to support newer NOR flashes.
> > The CS values need to be changed and support for u32 commands have to
> > be added to cfi_flash. I'll send patches the next days.
> 
> As for the u32 support, isn't everything in place with:
> CONFIG_DRIVER_CFI_BANK_WIDTH_4=y
> 
> Do you have some CS values for me to test with?
> 

Patches follow. Please test them.

Teresa

> I've got the impression that writes on the 64Mb nor pcm043 are much faster 
> than the old hw revisions with 32Mb nor.
> 
> Best regards
> Tim
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