linux-mtd: ubiattach taking long time

[Pintu Agarwal]

Dear Richard, Thank you so much for your reply. Please find some
comments inline.

On Mon, 25 Mar 2024 at 23:50, Richard Weinberger <richard at nod.at> wrote:
>
> Pintu,
>
> ----- Ursprüngliche Mail -----
> > Von: "Pintu Agarwal" <pintu.ping at gmail.com>
> > I have tried using fastmap as well, but still no difference.
> > Are there any other techniques to improve the ubiattach timing ?
> >
> > Logs:
> > ----------
> > Doing from initramfs:
> > {{{
> > [    6.949143][  T214] ubi0: attaching mtd54
> > [    8.023766][  T214] ubi0: scanning is finished
>
> No fastmap attach here.
>
> Make sure to set fm_autoconvert:
> http://www.linux-mtd.infradead.org/doc/ubi.html#L_fastmap
> If set, UBI create after a few writes a fastmap.
>
Yes, I have set fm_autoconvert=1 on cmdline and enabled fastmap on the
other logs.
{{{
[    0.000000][    T0] Kernel command line: ... fm_autoconvert=1
ubi.mtd=54,0,30 ...
[...]
[    6.702817][    T1] ubi0: default fastmap pool size: 170
[    6.702822][    T1] ubi0: default fastmap WL pool size: 85
[    6.702826][    T1] ubi0: attaching mtd54
[…]
[    7.784955][    T1] ubi0: scanning is finished
[    7.797135][    T1] ubi0: attached mtd54 (name "system", size 867 MiB)
}}}
Is there anything missing here ?
Can we increase the pool size ? Will it help to improve the timing ?

> Speaking of other techniques, you can improve scanning time also by
> tuning UBI for your NAND controller/setup.
> E.g. transferring only the amount of bytes needed for an header.
> Or reading without ECC and re-reading with ECC if the header CRC-check fails.
>
Sorry, I could not get this fully.
Is it possible to elaborate more with some reference ?
Do we have some special commands/parameters to do it if we use initramfs ?