linux-kernel - Re: [PATCH v6 00/17] mtd: nand: allow vendor specific detection/initialization

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Message-ID: <20170316094450.6a9e286d@bbrezillon>
Date:   Thu, 16 Mar 2017 09:44:50 +0100
From:   Boris Brezillon <boris.brezillon@...e-electrons.com>
To:     Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Richard Weinberger <richard@....at>,
        linux-mtd@...ts.infradead.org,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>
Cc:     Icenowy Zheng <icenowy@...c.xyz>, Valdis.Kletnieks@...edu,
        Aleksei Mamlin <mamlinav@...il.com>,
        Hans de Goede <hdegoede@...hat.com>,
        linux-kernel@...r.kernel.org,
        Thomas Petazzoni <thomas.petazzoni@...e-electrons.com>
Subject: Re: [PATCH v6 00/17] mtd: nand: allow vendor specific
 detection/initialization

+Thomas who is currently working on on-die ECC support for a Micron
NAND and is basing his work on this series.

On Mon,  9 Jan 2017 11:04:07 +0100
Boris Brezillon <boris.brezillon@...e-electrons.com> wrote:

> Hello,
> 
> I know I said it would be the last round, but I decided to change a few
> things after Marek's review.
> 
> Marek, Richard, I dropped your R-b/A-b tags on "mtd: nand: Add
> manufacturer specific initialization/detection steps" (patch 8) and
> "mtd: nand: Kill the MTD_NAND_IDS Kconfig option" (patch 6) since they
> changed a bit in v6.
> Can you have a look?
> 
> Marek, I did not address your concern regarding the use of the extern
> keyword for struct nand_manufacturer_ops defs. Let me know if this is
> something you really find important, and why. If you have a good reason
> to hide these objects behind an accessor, I might reconsider your
> suggestion.
> 
> This patch series is a step forward in supporting vendor-specific
> functionalities.
> This series is mainly moving vendor-specific initialization or
> detection code out of the core, but also introduces an infrastructure
> allowing support for vendor-specific features.
> 
> While those features might seem useless to most users, some of them are
> actually required on modern MLC/TLC NANDs (this is the case of read-retry
> support, which AFAICT has not been standardized by the JEDEC consortium).
> 
> Now, let's detail what's inside this patch-set.
> 
> Patches 1 to 5 are simple reworks simplifying auto-detection function
> prototypes, and clarifying their purpose.
> 
> Patch 6 is removing the MTD_NAND_IDS Kconfig option to avoid creating
> a nand_ids.ko module when MTD_NAND is enabled as a module. This prevents
> a future cross-dependency between nand.ko where all vendor specific
> code will rely and nand_ids.ko which will reference vendor-specific ops
> in its manufacturer table, which in turn is referenced by the core code
> linked in nand.ko.
> 
> Patch 7 is hiding NAND manufacturer table internals and exposing a
> helper to get a nand_manufacturer object from a manufacturer ID.
> 
> Patch 8 is introducing the vendor-specific initialization
> infrastructure.
> 
> Patches 9 to 14 are moving vendor-specific code into their respective
> nand_<vendor>.c files.
> 
> Patch 15 is taking a patch proposed by Hans and adding support for ECC
> requirements extraction from the samsung extended IDs. It seems to apply
> to all Samsung MLCs, but even if it's not the case, the detection code
> should be improved to support the new formats.
> 
> Patch 16 is adding support for advanced NAND ID decoding to the Hynix
> driver (OOB size, ECC and scrambling requirements extraction). Again
> this detection code might be incomplete, but I'd like people to extend
> it if required rather than adding new full-id entries in the nand_ids
> table.
> 
> And finally, patch 17 is showing how useful this vendor-specific stuff
> can be by implementing read-retry support for Hynix 1x nm MLCs. And
> trust me, you don't want to try using such a NAND without read-retry
> support ;).
> 
> As always, I'm open to any suggestion to improve this vendor-specific
> infrastructure, so please review the code :).

Applied, after fixing the bug reported by Julia.

I might decide to drop these patches if someone reports a regression,
hence the decision to apply them quite early in nand/next.