Hi,
On 10/01/20 12:17 am, Sam Protsenko wrote:
Fastboot specification [1] requires MMC to be filled with 0xFF's on "fastboot erase" command:
erase:%s Erase the indicated partition (clear to 0xFFs)Current "fastboot erase" implementation uses actual MMC erase operation blk_derase(), which can fill MMC either with 0x00 or 0xFF, depending on used MMC controller; from [2]:
The content of an explicitly erased memory range shall be '0' or '1' depending on different memory technology.For example, on BeagleBoard X15 it fills memory with '0'.
Furthermore, the minimal amount of memory blk_derase() can erase is "erase group size", and it's usually 512 KiB or more. So if we try to erase some partition which is smaller than 512 KiB, "fastboot erase" won't work at all, due to alignment. It's good practice to align all partitions to "erase group size" boundary, but it's not a strict requirement, so we just can't use blk_derase() due to this restriction.
In order to provide the consistent way to erase partitions, adhere to the fastboot spec, and fix erasing of small partitions, let's use regular MMC write operation and fill the partition with 0xFF.
[1] https://android.googlesource.com/platform/system/core/+/refs/tags/android-10... [2] https://www.jedec.org/system/files/docs/JESD84-A441.pdf
Signed-off-by: Sam Protsenko semen.protsenko@linaro.org ---Reviewed-by: Faiz Abbas faiz_abbas@ti.com
Thanks, Faiz