On Mon, 2015-01-26 at 16:33 -0600, Scott Wood wrote:
On Mon, 2015-01-26 at 16:24 -0600, Peter Tyser wrote:
The driver-specific verify_buf() function can be replaced with the standard read_page_raw() function to verify writes. This will allow verify_buf() to be removed from individual drivers. verify_buf() is no longer supported in mainline Linux, so it is a pain to continue supporting.
Any reason not to just remove this feature from U-Boot, as Linux has done?
The Linux change for reference: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=6...
I waffled about removing it, but leaned towards leaving it in because: - I didn't want to change the existing U-Boot behavior for other users. A google of 'u-boot "nand write"' shows a lot of examples that don't include verification of writes, and they should if we remove auto-verification.
- The reason it was removed in Linux was "Both UBI and JFFS2 are able to read verify what they wrote already. There are also MTD tests which do this verification." I thought U-Boot was more likely than Linux to use raw NAND writes without a filesystem, so leaving it in U- Boot made sense since the UBI/JFFS2 logic didn't apply as much here.
- I didn't think a lot of people would know they have to explicitly verify NAND contents after a write, since they'd assume it was like other memories that aren't as lossy.
- The penalty of slightly different code from Linux and a small performance hit was worth the gain of auto-verification to me. I viewed consolidating it into one small chunk of code as a happy medium.
The philosophical side of me said to remove it altogether, so I can see that perspective too. Peter