Dear Guennadi Liakhovetski,
In message Pine.LNX.4.64.0808312127560.6742@axis700.grange you wrote:
Erase area - this is all we erase, as opposed to one erase sector. On NOR this is limited by the environment size, on NAND by the number of blocks - the fifth parameter in the configuration file. This area may contain other useful data, which is first read in, then the whole area is erased, the environment is replaced in the read-in data, and it is written back - this is what I call the back-up process in the code.
We should not do that. We should erase only those sectors / blocks that we are actually attemmpting to write to.
And where's the difference between NAND and NOR flash? For NOR, the minimum "erase region" is a "block", either, which also can be 256KiB large.
This patch enables this for NOR - NAND support comes first with patch 6. So, it just enables placing the actual environment at any offset in the "erase area".
I don't understand. Why would such an offset be needed? The envrionment always starts right at the beginning of a sector or erase unit or block or however the storage device might call the smallest unit it can handle.
- /*
* Support environment anywhere within erase sectors: read out the* complete area to be erased, replace the environment image, write* the whole block back again.*/This comment should actually serve as an explanation...
But I don't understand it. What are "erase sectors"? How is the "area to be erased" defined? And what is the "block" (a flash block?) you are writing?
You are talking about "several pages" above. Where is this refelected in the code?
You mean in the commit comment? There I am talking about the future code - NAND case, which is not yet in this patch.
How shall anybody understand this, then? Description and code are not in sync - this is bad.
Frankly, I don't understand what you are trying to do. Please explain your implementation.
Hope, it is a bit clearer now. If not, please ask, will try to explain again.
You must provide a description of what you are actually doing. I do not understand your code.
Indeed, this patch series changes the programme in a non-trivial way, that's why I had to split this "NAND-support" into several patches, still some of them seem to be not clear enough.
Well, splitting complex things that obviously belong together into smaller pieces and confronting the reviewer with a puzzle of unrelated bits does not exactly make things "clear".
See previous message - I guess the whole splitting is just contra- productive.
Best regards,
Wolfgang Denk