linux-kernel - Re: [PATCH] mtd: spi-nor: scale up timeout for full-chip erase

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Date:	Tue, 29 Sep 2015 13:26:01 -0700
From:	Brian Norris <computersforpeace@...il.com>
To:	linux-mtd@...ts.infradead.org
Cc:	linux-kernel@...r.kernel.org, Furquan Shaikh <furquan@...gle.com>,
	Stephen Barber <smbarber@...omium.org>,
	Marek Vasut <marex@...x.de>,
	Rafał Miłecki <zajec5@...il.com>,
	Huang Shijie <shijie.huang@....com>
Subject: Re: [PATCH] mtd: spi-nor: scale up timeout for full-chip erase

On Fri, Sep 18, 2015 at 02:59:17PM -0700, Brian Norris wrote:
> From: Furquan Shaikh <furquan@...gle.com>
> 
> This patch fixes timeout issues seen on large NOR flash (e.g., 16MB
> w25q128fw) when using ioctl(MEMERASE) with offset=0 and length=16M. The
> input parameters matter because spi_nor_erase() uses a different code
> path for full-chip erase, where we use the SPINOR_OP_CHIP_ERASE (0xc7)
> opcode.
> 
> Fix: use a different timeout for full-chip erase than for other
> commands.
> 
> While most operations can be expected to perform relatively similarly
> across a variety of NOR flash types and sizes (and therefore might as
> well use a similar timeout to keep things simple), full-chip erase is
> unique, because the time it typically takes to complete:
> (1) is much larger than most operations and
> (2) scales with the size of the flash.
> 
> Let's base our timeout on the original comments stuck here -- that a 2MB
> flash requires max 40s to erase.
> 
> Small survey of a few flash datasheets I have lying around:
> 
>   Chip         Size (MB)   Max chip erase (seconds)
>   ----         --------    ------------------------
>   w25q32fw     4           50
>   w25q64cv     8           30
>   w25q64fw     8           100
>   w25q128fw    16          200
>   s25fl128s    16          ~256
>   s25fl256s    32          ~512
> 
> From this data, it seems plenty sufficient to say we need to wait for
> 40 seconds for each 2MB of flash.
> 
> After this change, it might make some sense to decrease the timeout for
> everything else, as even the most extreme operations (single block
> erase?) shouldn't take more than a handful of seconds. But for safety,
> let's leave it as-is. It's only an error case, after all, so we don't
> exactly need to optimize it.
> 
> Signed-off-by: Furquan Shaikh <furquan@...gle.com>
> Signed-off-by: Brian Norris <computersforpeace@...il.com>

Pushed to l2-mtd.git
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/