>From: Jeroen Hofstee [mailto:jer...@myspectrum.nl] [...] > >The gpmc will fail in hw ecc mode when trying to do subpage reads. Pekon any >suggestion for the elm mode, or should this bit just be cleared >unconditionally? > There are two reasons for not supporting sub-page feature in OMAP platforms:
(1) ELM h/w engine has limitation that it can support ecc-corrections only in junks of 512Bytes. Now some flash devices (like page-size=4K) have sub-page = 4k/4 = 1k. Thus, it becomes trivial (though not impossible) to support sub-page. Hence, for now sub-page feature has been marked as 'un-supported' for OMAP. (2) Also, we found that sub-page feature was not giving much benefit, except improving data-packing density on given NAND to some extent. Like in UBIFS, having sub-page feature packs 'erase-header' and volume-id-header' into single page, thereby saving 1 page for every erase-block. Memory Saved = (1x page-size)/ block-size = 2k / 128k = 1/64 ~ 1.5 % (raw calculations). Hence, in summary, yes you can un-conditionally clear the sub-page read bit. with regards, pekon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot