Message-ID: <576D75B8.2050406@ti.com>
Date:	Fri, 24 Jun 2016 13:02:32 -0500
From:	Nishanth Menon <nm@...com>
To:	Guenter Roeck <linux@...ck-us.net>
CC:	Jean Delvare <jdelvare@...e.com>, <linux-hwmon@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/5] hwmon: (tmp102) Use devm_add_action to register
 cleanup function

On 06/24/2016 11:36 AM, Guenter Roeck wrote:
> On Fri, Jun 24, 2016 at 10:23:10AM -0500, Nishanth Menon wrote:
>> On 06/24/2016 09:54 AM, Guenter Roeck wrote:
>>> On 06/24/2016 07:30 AM, Guenter Roeck wrote:
>>>> Hi Nishanth,
>>>>
>>>> On 06/24/2016 07:13 AM, Nishanth Menon wrote:
>>>>> On 06/23/2016 07:28 PM, Guenter Roeck wrote:
>>>>>> By registering a cleanup function with devm_add_action(), we can
>>>>>> simplify the error path in the probe function and drop the remove
>>>>>> function entirely.
>>>>>>
>>>>>> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
>>>>>
>>>>> I dont seem to have a cover letter to reply to... but anyways..
>>>>>
>>>>> Before: http://pastebin.ubuntu.com/17801376/
>>>>> After all 5 patches: http://pastebin.ubuntu.com/17801824/
>>>>>
>>>>> Fails on beagleboard-X15 with:
>>>>> [   36.781509] tmp102 0-0048: No cache defaults, reading back from HW
>>>>> [   36.795940] tmp102 0-0048: unexpected config register value
>>>>>
>>>>> I have'nt bisected down on the specific patch in the series. Have you had a chance to test the series?
>>>>>
>>>>>
>>>>
>>>> Thanks for testing. Yes, I did test it. Maybe different chip revisions, or different
>>>> initial config register values and I messed up there. Can you send me the output
>>>> of i2cdump (word wide) ?
>>>>
>>>
>>> Before 5 patches:
>>>> # i2cdump -f 0 0x48 w
>>>>      0,8  1,9  2,a  3,b  4,c  5,d  6,e  7,f
>>>> 00: 7912 b062 004b 0050 c018 e006 0000 0000 
> 
> [ ... ]
>>>
>>> After 5 patches:
>>>>  i2cdump -y 0 0x48 w
>>>>      0,8  1,9  2,a  3,b  4,c  5,d  6,e  7,f
>>>> 00: 5024 a060 004b 0050 c018 e006 0000 0000 
> 
> [ .... ]
> 
>> I can try and debug the series once I get some spare time, might be
>> over the weekend or next week.
> 
> The register map, at least the initial one, is pretty much the same as mine
> and as expected. The configuration register in the second map is messed up,
> possible because of a write with wrong endianness.

Got a few mins skipping lunch.. ;)

I did a quick bisect, and it is indeed the patch #5 that breaks.
added http://pastebin.ubuntu.com/17812044/ and got:

tmp102 0-0048: regval = 0x0000ffff

That was weird. Does'nt look like endian-ness swap thingy

So, did the following hack to see all messages flowing in and out from
0x48 at bus controller driver level: http://pastebin.ubuntu.com/17813093/
/ # dmesg|grep XXX
/ #

Before patch #5 (and on next-20160624):
the same diff gave:
http://pastebin.ubuntu.com/17813303/



> I bet the regmap_read() of the configuration register returns 0xa060 (or
> 0xb062) instead of 0x60a0 / 0x62b0 on your system. If you find the time,
> it would be great if you can confirm by printing the register value with
> the "unexpected config register value" message (guess I should have left
> that in place - I used it during testing ;-).
> 
> If that is the case, I'll probably have to drop the regmap changes, at least
> for now. It would mean that regmap is broken for chips like the LM75 (ie
> for all chips with 16-bit registers) on controllers supporting I2C_FUNC_I2C.

It does look like everything is getting cached out and no actual reads
are actually getting through to the bus controller driver even.

I tested on next-20160624 and used omap2plus_defconfig for the test.


-- 
Regards,
Nishanth Menon

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