linux-kernel - Re: mc13xxx-core: kernel hangs after 'regmap

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Message-Id: <201205221053.21792.marc@cpdesign.com.au>
Date:	Tue, 22 May 2012 10:53:21 +1000
From:	Marc Reilly <marc@...esign.com.au>
To:	Fabio Estevam <festevam@...il.com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Samuel Ortiz <sameo@...ux.intel.com>,
	Sascha Hauer <kernel@...gutronix.de>,
	Philippe Rétornaz <philippe.retornaz@...l.ch>,
	"linux-kernel" <linux-kernel@...r.kernel.org>
Subject: Re: mc13xxx-core: kernel hangs after 'regmap_read'

Hi Fabio,

On Tuesday, May 22, 2012 02:06:55 AM Fabio Estevam wrote:
> Hi Marc,
> 
> I am running linux-next 3.4.0-next-20120521 on a mx31pdk board that
> has a mc13783 PMIC connected to SPI.
> 
> I am getting a kernel hang after 'regmap_read' inside mc13xxx_reg_read
> function.
> 
> Does it work fine for you on your mx35 board? Am I missing any recent
> patch?

I tested linux-next/next-20120521, no extra patches. I got build errors for 
something to do with usb udc, and start-up panic for the nand driver. 
Disabling both of these got me to a login. Then:

mount -t debugfs none /sys/kernel/debug
cat /sys/kernel/debug/regmap/0-0008/registers

00: 004cc0
01: ffffff
02: 185cc0
03: 000005
04: ffffff
05: 00401c
06: 000200
07: 0045d0
08: 000000
09: 000005
0a: 00147a
0b: 000000
0c: 000000
0d: 0b0040
0e: 000000
0f: 400032
10: 000000
11: 000000
12: 000001
13: 000000
14: 013326
15: 01ffff
...

Which looks correct.


> 
> My understanding is that you have only tested i2c connection with this
> PMIC. Is this correct?
That's correct. I don't have any SPI connected hardware to test with. Shawn 
tested SPI operation for an earlier version of the patch series, but that was 
before the regmap changes.


> Any ideas on how to solve this issue is appreciated.
My first suspicion is with the regmap register format of the mc13xxx for SPI. 
It was a new format which introduced a padding bit. I wonder if Mark Brown can 
comment on whether any other devices are using it successfully. (Sorry I can't 
offer more insights there).

Does your crash occur during mc13xxx_spi_probe? does mc13xxx_common_init() get 
called?


Cheers,
Marc

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