linux-kernel - Re: [PATCH v4 02/10] mtd: st_spi_fsm: Fetch boot device locations from DT match tables

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Message-ID: <20150206042744.GK18140@ld-irv-0074>
Date:	Thu, 5 Feb 2015 20:27:44 -0800
From:	Brian Norris <computersforpeace@...il.com>
To:	Lee Jones <lee.jones@...aro.org>
Cc:	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	kernel@...inux.com, linux-mtd@...ts.infradead.org,
	devicetree@...r.kernel.org
Subject: Re: [PATCH v4 02/10] mtd: st_spi_fsm: Fetch boot device locations
 from DT match tables

On Wed, Jan 21, 2015 at 03:24:20PM +0000, Lee Jones wrote:
> To trim down on the amount of properties used by this driver and to conform
> to the newly agreed method of acquiring syscfg registers/offsets, we now
> obtain this information using match tables.

Where did this agreement happen? Are you only referring to the previous
patch?

I think I asked this previously, and I didn't get an answer.

Also, I realized that all this boot device / syscfg gymnastics is just
for one simple fact; your driver is trying to hide the fact that your
system can't reliably handle 4-byte addressing for the boot device. Even
if you try your best at toggling 4-byte addressing before/after each
read/write/erase, you still are vulnerable to power cuts during the
operation. This is a bad design, and we have consistently agreed that we
aren't going to work around that in Linux.

Better solutions: hook up a reset line to your flash; improve your boot
ROM / bootloader to handle 4-byte addressing for large flash.

What's the possibility of dropping all this 4-byte address toggling
shenanigans? This will be a blocker to merging with spi-nor.c.

> In the process we are deprecating the old generic compatible string and
> providing 3 shiny new ones for each of the support platforms.  The
> deprecated compatible string will be removed in due course.

Aren't you already removing the compatible string? (You changed this in
the latest revision.)

> Cc: devicetree@...r.kernel.org
> Signed-off-by: Lee Jones <lee.jones@...aro.org>

[snip]

Brian
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