[PATCHv2 1/1] mtd: gpmi: make blockmark swapping optional

[Lothar Waßmann]

Hi,

Huang Shijie wrote:
> 于 2014年03月26日 16:51, Lothar Waßmann 写道:
> > I don't see why this should not be supported on i.MX28 (i.MX23 doesn't
> > do byteswapping anyway, so this wouldn't change anything for i.MX23).
> > The partitions used by Linux need not necessarily be accessible for the
> > Boot ROM code (and vice versa).
> But the first partition used to store the u-boot is accessible for the ROM.
> 
Whether this partition is available to Linux depends on the partition table
passed in the DT.

> Please see "Figure 12-13" in the 12.12.1.12:
>    "In order to preserve the BI (bad block information), flash updater 
> or gang programmer
> applications need to swap Bad Block Information (BI) data to byte 0 of 
> metadata area for
> every page before programming NAND Flash. ROM when loading firmware, 
> copies back
> the value at metadata[0] to BI offset in page data. The following figure 
> shows how the
> factory bad block marker is preserved."
> 
The inspection of the BB markers is only a fallback for the case that
there is no DBBT. From the same chapter that you quoted above:
| ROM uses DBBT to skip any bad block that falls within firmware data
| on NAND Flash device.
| If the address of DBBT Search Area in FCB is 0, ROM will rely on
| factory marked bad block markers to find out if a block is good or bad.

Thus, even the boot ROM of i.MX28 can well live without blockmark
swapping.


Lothar Waßmann
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