[PATCH 2/2] env: add CONFIG_ENV_SECT_SIZE_AUTO

[Rasmus Villemoes]

On 06/05/2020 12.18, Joakim Tjernlund wrote:
> On Wed, 2020-05-06 at 12:00 +0200, Joakim Tjernlund wrote:
>> On Wed, 2020-05-06 at 11:37 +0200, Rasmus Villemoes wrote:
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>>>
>>> On 06/05/2020 11.21, Joakim Tjernlund wrote:
>>>
>>>> I can test NOR Flash ,I am on an older u-boot ATM but fw_setenv stuff should be simple to backport
>>>> How would fw_env.config be dealt with? Just ignored when auto size?
>>>
>>> AFAIK, the U-Boot configuration doesn't affect the userspace fw_env
>>> tools, so auto size has to be opt-in separately in fw_env.config, which
>>> is where I did use 0 to mean auto (see the referenced commit
>>> e282c422e0). You should be able to test that part already with just
>>> fw_setenv built from master and an appropriate fw_env.config [or perhaps
>>> you need to add another "mtdinfo.type == ..." condition first].
>>
>> Oh, I misunderstood then. I was mostly interested in fw_setenv ATM
>> Looking at your fw_setenv commit I have one question:
>> Will this auto mode also work when erase size < env size ?
>> We have the case:
>>
>> # MTD device name	Device offset	Env. size	Flash sector size
> 
> From my POV, this "Flash sector size" name is misleading. "Size to erase" would be better.
> It must be >= Env. size and a multiple of EB size.
> auto would mean to select a size >= Env. size, round up to closest multiple of EB size.

No, it is indeed supposed to be the flash sector size, and _not_ the
size to erase; that's why the code has logic to compute how many sectors
to erase (which you can also optionally specify in a fifth column, but
as I said, that's done automatically if not specified), and the erase
size is then, later yet, of course computed as (erase size)*#sectors.

All that has nothing at all to do with my patch, that's how it all used
to work.

>>  /dev/mtd1		0x0000		0x2000		0x00001000
>>
>> Above does not work because EB < Env. size, one have to set the sector size
>> to >= Env. size(0x2000)

Are you sure? As I said, it works just fine on my end. The only thing my
auto-patch does is to make

/dev/mtd1		0x0000		0x2000		0x00001000

equivalent to

/dev/mtd1		0x0000		0x2000		0

if the flash does have 4k erase size, so my patch wouldn't make the
latter work if the former didn't already. [But again, the reason I can't
use the former is to be compatible with the boards that have 64K erase
size].

Rasmus