Hey guys, I've posted a patch to support the eMMC boot partitions found on the TI DRA7xx EVM the other day, and I've been looking at what exactly happens with the 'mmc open ...' and 'mmc close ...' commands the CONFIG_SUPPORT_EMMC_BOOT enables. I've got a few questions about how exactly the support works on the SMDK5250 and what your platform requirements are, so we can re-work the code to be a bit more generic.
Why do we have it as "open" and "close" ? Is this because it's a version 4.2[1] style device? I'm working with 4.3-compatible (it's actually 4.41, but same method just larger partitions) one and that can be done with setting EXT_CSD[179] (BOOT_CONFIG / Boot configuration) _and_ EXT_CSD[177] to a specific and different value than we've hard-coded now. I would like to change things to be: "mmc open <device>" - Note required for eMMC 4.2 boot method. "mmc close <device>" - Same "mmc bootpart <device> <partition>" - Used for eMMC 4.3 and later boot sequence option 1/2 "mmc bootbus <device> <value>" - Note used in all boot sequences This would make the SMDK5250 sequence be (based on how I think it works today): mmc dev ... mmc open mmc write ... mmc bootpart ... mmc bootbus ... mmc close And the DRA7xx sequence be: mmc dev ... mmc write ... mmc bootpart ... mmc bootbus ... Comments? I plan to start down this path shortly, thanks! [1]: http://www.micron.com/~/media/Documents/Products/Technical%20Note/NAND%20Flash/tn2918.pdf -- Tom
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