[U-Boot-Users] [PATCH] cfi_flash.c patches

[Woodruff, Richard]

Tolunay,

Several Intel chips do provide hardware level protection locks which get
cleared at reset.

It is useful to use this hardware feature at boot to help protect flash
sectors from upper level code during normal operation.  The u-boot
software lock is nice, but doesn't extend beyond u-boot code while the
hardware lock does.

The difference in behavior between chips is the issue here.  Perhaps it
is better to add another compile time flag which allows the hardware
features to be used on such chips.

Your point is one _hardware_ features behavior should be valued over
another's.  Having them both via flags is probably the way to go.

Regards,
Richard W.

> -----Original Message-----
> From: u-boot-users-admin at lists.sourceforge.net [mailto:u-boot-users-
> admin at lists.sourceforge.net] On Behalf Of Tolunay Orkun
> Sent: Friday, August 19, 2005 1:37 PM
> To: Sangmoon Kim
> Cc: u-boot; Wolfgang Denk
> Subject: Re: [U-Boot-Users] [PATCH] cfi_flash.c patches
> 
> Dear Sangmoon,
> 
> I've examined your patch for clearing the protection of flash sectors
> automatically during flash init. As a matter of fact a similar patch
was
> also proposed by someone else and I had commented on it as well.
> 
> I think this is wrong approach. These sectors are protected for a
reason
> (to prevent accidental writes - forgetting to enable protection).
> 
> You should enable CFG_FLASH_PROTECTION in your board config file. If
you
> don't do this U-Boot will do software protection of sectors (which is
> really for those flash chips with no hardware protection capability)
and
> "protect off" will not issue unlock commands as you may have
witnessed.
> 
> CFG_FLASH_PROTECTION will enable the "protect  off" command to disable
> protection properly on these sectors as it should.
> 
> IMHO, No patch is needed here! Perhaps we need to add a couple of
> comment lines in README (DULG?) for documentation purposes. Wolfgang,
> can you comment here.
> 
> Best regards,
> Tolunay
> 
> Sangmoon Kim wrote:
> > Hi,
> > The two patches attached are for drivers/cfi_flash.c.
> >
> > cfi_flash-protect.patch adds CFG_FLASH_PROTECT_CLEAR
> > because for some flash memories(such as 28F320C3)
> > all banks are protected after reset.
> >
> > cfi_flash-buffer.patch makes write_buff not to call
> > flash_write_cfibuffer if buffer_size is1.
> > Because for flash memories with buffer_size 1,
> > buffer write is not supported.
> >
> > Regards,
> > Sangmoon Kim
> 
> 
> 
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