Re: [PATCH 0/8] SUNIV SPI NAND support in SPL

[Sam Edwards <cfsworks@gmail.com>]

Hi again Icenowy,

On 6/6/23 17:09, Sam Edwards wrote:
> Still, I believe it's sensible that, when we know for sure we're coming 
> from SPI-NAND (because it's a newer sunxi that reports 0x04, or we know 
> from the suniv stack-checking hack), we should call that its own SPL 
> load method, which does not fall back to SPI-NOR. The SPI(-NOR) load 
> method naturally has to implement the try-NAND-first logic for some of 
> these SoCs, but perhaps we could call it a "quirk" and only do that for 
> chips that aren't known to report SPI-NAND directly?

Since other methods that care about flash type (e.g. env_get_location) 
don't understand BOOT_DEVICE_SPI to mean "SPI, but the actual flash type 
is ambiguous," I'm starting to think we need to resolve the ambiguity 
*before* the load method runs.

What are your thoughts on this:
1. Introduce SUNXI_BOOTED_FROM_SPI_NAND, value 4 (matching the value 
used by Allwinner's newer BROMs).
2. Map SUNIV_BOOTED_FROM_NAND to SUNXI_BOOTED_FROM_SPI_NAND.
3. Map SUNXI_BOOTED_FROM_SPI_NAND to BOOT_DEVICE_NAND (and not _SPI).
4. Implement the SPI-NAND stuff to provide `nand_spl_load_image` (so 
that the common SPL framework's NAND loader can take care of it). 
Possibly go even further and implement the methods needed by the UBI 
loader too.
5. On sunxis (e.g. V3s) which are known to report SUNXI_BOOTED_FROM_SPI 
for SPI-NAND, add a small check to sunxi_get_boot_device() which 
disambiguates this situation by probing for SPI-NAND.

If #4 isn't really feasible, we might instead want to introduce a 
BOOT_DEVICE_SPI_NAND, but I don't know if adding sunxi to the list of 
platforms that have their own BOOT_DEVICE_ names is a great call.

In any case, I'd hope also to see some kind of bad block handling in 
here -- a simple check for a bad block each time we get to page 0 (which 
skips to the next block) should be pretty easy, don't you think?

Any thoughts? Any other way I can be of service? (Feel free to delegate 
some of these ideas to me if you think they're good but don't have the 
time to execute them!)

Warm regards,
Sam