linux-kernel - Re: [PATCH v3.4-rc3] MTD: NAND: ams-delta: Fix request_mem

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Message-ID: <20120504171125.GD5613@atomide.com>
Date:	Fri, 4 May 2012 10:11:25 -0700
From:	Tony Lindgren <tony@...mide.com>
To:	Janusz Krzysztofik <jkrzyszt@....icnet.pl>
Cc:	dedekind1@...il.com, David Woodhouse <dwmw2@...radead.org>,
	Artem Bityutskiy <Artem.Bityutskiy@...ux.intel.com>,
	linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
	linux-omap@...r.kernel.org
Subject: Re: [PATCH v3.4-rc3] MTD: NAND: ams-delta: Fix
 request_mem_region() failure

Hi,

* Janusz Krzysztofik <jkrzyszt@....icnet.pl> [120430 11:15]:
> Dnia czwartek, 26 kwietnia 2012 08:20:59 Artem Bityutskiy pisze:
> > On Wed, 2012-04-25 at 19:01 +0200, Janusz Krzysztofik wrote:
> > > Both drivers use separate subsets of registers that belong to the 
> OMAP1 
> > > MPU I/O device, but are used for controlling different sets of I/O 
> pins. 
> > > The NAND driver reads/writes the folowing registers:
> > > - OMAP_MPUIO_INPUT_LATCH,
> > > - OMAP_MPUIO_OUTPUT,
> > > - OMAP_MPUIO_IO_CNTL,
> > > while the keypad driver - the following:
> > > - OMAP_MPUIO_KBR_LATCH,
> > > - OMAP_MPUIO_KBC,
> > > - OMAP_MPUIO_KBD_MASKIT
> > > - OMAP_MPUIO_GPIO_DEBOUNCING.
> > > Both subsets are non-overlapping, and we rely on the drivers being 
> free 
> > > of bugs and doing their job correctly, not stepping on each others' 
> > > feet, I guess.
> > 
> > First of all, I think this information should be in the commit 
> message.
> > Also, some sort of comment in the driver code would be nice.
> > 
> > If locking the memory region is too coarse approach, the should have a
> > small separate omap-specific MPUIO subsystem which will be used by
> > drivers to access MPUIO?
> > 
> > Another question - should request_mem_region() be also removed from 
> the
> > omap-gpio driver then? I think it is more sensible to put a comment
> > there that it is sharing MPIO with other drivers,  instead of having 
> an
> > illusion of exclusive memory region ownership.
> > 
> > But this is up to the OMAP community - I can take this patch to my
> > l2-mtd tree if you get an ack from Tony or other OMAP guys.
> 
> Tony,
> Would I get your Ack for this fix if I extend the commit message as Artem 
> suggested? If not, what do you think should be a correct way to fix the 
> regression?

Well how about adding some exported functions to drivers/gpio/gpio_omap.c
like omap_mpuio_latch?

For the regression fix, if you guys want to do what Janusz is suggesting,
then assuming the patch description also contains some decent long term
plan to properly fix it:

Acked-by: Tony Lindgren <tony@...mide.com>
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