On Thu, Oct 6, 2016 at 9:21 PM, George McCollister <[email protected]> wrote: > On Thu, Oct 6, 2016 at 10:27 AM, Jagan Teki <[email protected]> wrote: >> On Thu, Oct 6, 2016 at 8:32 PM, George McCollister >> <[email protected]> wrote: >>> I'm looking into adding a sub-command to sf to protect status >>> registers on Winbond SPI flash parts via the status register protect >>> bits SRP0, SRP1. I propose the sub-command be named sr-protect. >>> >>> My use case is simple, I want to make the SPI flash read-only when the >>> /WP pin is low. To do this I must do 'sf protect lock 0 $size' then >>> set SRP0 to 1 and hold the /WP pin low. Although my use case doesn't >>> require it, setting SRP1 to 1 allows either Power Supply Lock-Down or >>> One Time Program (if supported by hardware) and I would probably add >>> support for these as well. >>> >>> All of the current Winbond SPI NOR flash part datasheets that I've >>> looked at show that the parts support the same locking implemented in >>> stm_lock() even though SPI_FLASH_CFI_MFR_WINBOND is not in the list of >>> vendors which use the function. I'll change this to make >>> SPI_FLASH_CFI_MFR_WINBOND parts use stm_lock(), stm_unlock(), >>> stm_is_locked(). >> >> Does stm_lock can't protect the Winbond? how different is in the >> process of doing when compared to stm? > > stm_lock() does work with the Winbond parts. The issue is that you can > simply unlock from software (stm_unlock). To make it impossible to > write to the flash from software you must use stm_lock() then use the > status register protect bits to prevent an unlock.
So, you need even if stm_unlock triggered from cmd flash still lock? then what is the point of using unlock? Just describe me what is the diff b/w winbond vs other stm flash in case of lock and unlocking. thanks! -- Jagan Teki Free Software Engineer | www.openedev.com U-Boot, Linux | Upstream Maintainer Hyderabad, India. _______________________________________________ U-Boot mailing list [email protected] http://lists.denx.de/mailman/listinfo/u-boot
