eMMC boot partition booting and SMDK5250 support
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
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Quoted 32 lines · Tom Rini
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_BOOTenables. 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 sequencesThis 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
Quoted 5 lines
And the DRA7xx sequence be:
mmc dev ...
mmc write ...
mmc bootpart ...
mmc bootbus ...
Oh! And I forgot the current 'bootpart' which appears to be a resize operation would become 'bootpart-resize'.
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Jaehoon,
How you think?
Quoted 42 lines · Tom Rini
Quoted 32 lines · Tom Rini
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_BOOTenables. 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 sequencesThis 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 closeQuoted 5 lines
And the DRA7xx sequence be:
mmc dev ...
mmc write ...
mmc bootpart ...
mmc bootbus ...Oh! And I forgot the current 'bootpart' which appears to be a resize operation would become 'bootpart-resize'.
Quoted 9 lines · Tom Rini
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_BOOTenables. 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.
Quoted 6 lines
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.
Or, is this done to save a step in terms of issuing 'mmc dev' commands and thus the 'close' is to done to get people back to the user partition? Thanks!
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