From: Valdis.Kletnieks@vt.edu
To: Boris Brezillon <boris.brezillon@free-electrons.com>
Cc: Richard Weinberger <richard@nod.at>,
linux-mtd@lists.infradead.org,
David Woodhouse <dwmw2@infradead.org>,
Brian Norris <computersforpeace@gmail.com>,
Hans de Goede <hdegoede@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 13/15] mtd: nand: samsung: retrieve ECC requirements from extended ID
Date: Mon, 30 May 2016 16:56:09 -0400 [thread overview]
Message-ID: <137285.1464641769@turing-police.cc.vt.edu> (raw)
In-Reply-To: <20160530094446.5edec3ac@bbrezillon>
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On Mon, 30 May 2016 09:44:46 +0200, Boris Brezillon said:
> Hi Valdis,
> Actually, that was my first reaction [1], but the more I think about it
> the more I realize it's a non-issue.
> AFAICT, there's no full-id entries for Samsung NANDs in the nand_ids
> table, so this either means there's no real users of Samsung MLCs or
> NAND controller drivers connecting to those chips don't care about the
> ->ecc_{step_ds,strength_ds} fields.
I'm mostly, though not totally convinced (not having looked closely at
the existing code). There's still a possible issue with the distinction
between:
A) "driver never references the variable" and
B) driver check if it's zero, and acts like it doesn't care if it is, but if
it's non-zero, it goes ahead and uses it, with possible hilarity ensuing if the
value is wrong.
Should be pretty easy for somebody who knows the code better than I to rule
out case B fairly quickly...
> I agree that the solution is not perfect, but I'd prefer seeing the
> NAND detection code iteratively improved than rejecting everything
> until we're 100% sure that all cases are correctly handled (which might
> never happen since NAND vendors introduce new NAND ID scheme if they
> need to).
>
> BTW, do you have Samsung datasheets describing a different NAND ID
> format, or is it purely hypothetical?
Mostly hypothetical. I've just seen too many patches that assume "all chips
from vendor XYZ do *this*" that were not at all corrrect.
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next prev parent reply other threads:[~2016-05-30 20:58 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-27 12:54 [PATCH 00/15] mtd: nand: allow vendor specific detection/initialization Boris Brezillon
2016-05-27 12:54 ` [PATCH 01/15] mtd: nand: get rid of the mtd parameter in all auto-detection functions Boris Brezillon
2016-05-27 12:54 ` [PATCH 02/15] mtd: nand: store nand ID in struct nand_chip Boris Brezillon
2016-05-27 12:54 ` [PATCH 03/15] mtd: nand: get rid of busw parameter Boris Brezillon
2016-05-27 12:54 ` [PATCH 04/15] mtd: nand: rename nand_get_flash_type() into nand_detect() Boris Brezillon
2016-05-27 12:54 ` [PATCH 05/15] mtd: nand: add vendor specific initialization step Boris Brezillon
2016-05-27 12:54 ` [PATCH 06/15] mtd: nand: kill the MTD_NAND_IDS Kconfig option Boris Brezillon
2016-05-27 12:54 ` [PATCH 07/15] mtd: nand: move samsung specific initialization in nand_samsung.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 08/15] mtd: nand: move hynix specific initialization in nand_hynix.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 09/15] mtd: nand: move toshiba specific initialization in nand_toshiba.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 10/15] mtd: nand: move micron specific initialization in nand_micron.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 11/15] mtd: nand: move AMD/Spansion specific initialization in nand_amd.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 12/15] mtd: nand: move Macronix specific initialization in nand_macronix.c Boris Brezillon
2016-05-27 12:54 ` [PATCH 13/15] mtd: nand: samsung: retrieve ECC requirements from extended ID Boris Brezillon
2016-05-30 0:20 ` Valdis.Kletnieks
2016-05-30 7:44 ` Boris Brezillon
2016-05-30 20:56 ` Valdis.Kletnieks [this message]
2016-05-30 22:28 ` Boris Brezillon
2016-05-30 22:32 ` Boris Brezillon
2016-05-27 12:55 ` [PATCH 14/15] mtd: nand: hynix: rework NAND ID decoding to extract more information Boris Brezillon
2016-05-27 12:55 ` [PATCH 15/15] mtd: nand: hynix: add read-retry support for 1x nm MLC NANDs Boris Brezillon
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