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Date:	Thu, 25 Dec 2014 00:53:51 +0100
From:	Gabriele Mazzotta <gabriele.mzt@...il.com>
To:	Andrew Duggan <aduggan@...aptics.com>
Cc:	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
	benjamin.tissoires@...hat.com, jkosina@...e.cz
Subject: Re: NULL pointer dereference in i2c-hid

On Friday 12 December 2014 11:12:50 Andrew Duggan wrote:
> On 12/12/2014 12:12 AM, Gabriele Mazzotta wrote:
> > On Thursday 11 December 2014 16:26:00 Andrew Duggan wrote:
> >> On 12/11/2014 01:57 PM, Gabriele Mazzotta wrote:
> >>> On Thursday 11 December 2014 13:34:02 Andrew Duggan wrote:
> >>>> On 12/11/2014 01:17 PM, Gabriele Mazzotta wrote:
> >>>>> On Thursday 11 December 2014 12:46:53 Andrew Duggan wrote:
> >>>>>> On 12/11/2014 11:40 AM, Gabriele Mazzotta wrote:
> >>>>>>> On Thursday 11 December 2014 11:21:43 Andrew Duggan wrote:
> >>>>>>>> On 12/11/2014 11:11 AM, Gabriele Mazzotta wrote:
> >>>>>>>>> On Thursday 11 December 2014 10:40:05 Andrew Duggan wrote:
> >>>>>>>>>> On 12/11/2014 10:16 AM, Gabriele Mazzotta wrote:
> >>>>>>>>>>> On Thursday 11 December 2014 16:03:07 Mika Westerberg wrote:
> >>>>>>>>>>>> On Thu, Dec 11, 2014 at 10:58:01AM +0200, Mika Westerberg wrote:
> >>>>>>>>>>>>> On Wed, Dec 10, 2014 at 06:04:51PM +0100, Gabriele Mazzotta wrote:
> >>>>>>>>>>>>>> my laptop uses a touchpad that needs hid-rmi along with i2c-hid to work.
> >>>>>>>>>>>>>> i2c-hid and hid-rmi can be loaded and unloaded independelty from each
> >>>>>>>>>>>>>> other, however since 34f439e4afcd ("HID: i2c-hid: add runtime PM support")
> >>>>>>>>>>>>>> if I unload hid-rmi and after it I also unload i2c-hid, I get a NULL
> >>>>>>>>>>>>>> pointer dereference.
> >>>>>>>>>>>>> I'll look into this.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I can reproduce this easily with i2c-hid + hid-multitouch following your
> >>>>>>>>>>>>> directions.
> >>>>>>>>>>>> Can you try the below patch?
> >>>>>>>>>>>>
> >>>>>>>>>>>> I think we shouldn't free buffers yet in ->stop() because we need the
> >>>>>>>>>>>> command buffer sending power commands to the device. Also it seems that
> >>>>>>>>>>>> ->start() re-allocates buffers anyway if maximum size increases.
> >>>>>>>>>>>>
> >>>>>>>>>>>> It shouldn't even leak memory as we release buffers at ->remove()
> >>>>>>>>>>>> anyway.
> >>>>>>>>>>>>
> >>>>>>>>>>>> diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
> >>>>>>>>>>>> index 62cec01937ea..68a8c938feea 100644
> >>>>>>>>>>>> --- a/drivers/hid/i2c-hid/i2c-hid.c
> >>>>>>>>>>>> +++ b/drivers/hid/i2c-hid/i2c-hid.c
> >>>>>>>>>>>> @@ -705,12 +705,7 @@ static int i2c_hid_start(struct hid_device *hid)
> >>>>>>>>>>>>        
> >>>>>>>>>>>>        static void i2c_hid_stop(struct hid_device *hid)
> >>>>>>>>>>>>        {
> >>>>>>>>>>>> -	struct i2c_client *client = hid->driver_data;
> >>>>>>>>>>>> -	struct i2c_hid *ihid = i2c_get_clientdata(client);
> >>>>>>>>>>>> -
> >>>>>>>>>>>>        	hid->claimed = 0;
> >>>>>>>>>>>> -
> >>>>>>>>>>>> -	i2c_hid_free_buffers(ihid);
> >>>>>>>>>>>>        }
> >>>>>>>>>>>>        
> >>>>>>>>>>>>        static int i2c_hid_open(struct hid_device *hid)
> >>>>>>>>>>> Yes, it works, thanks.
> >>>>>>>>>>>
> >>>>>>>>>>> This change seems to also prevent kernel ooops when I unload either
> >>>>>>>>>>> i2c-hid or i2c-designware-platform while the touchpad is in use,
> >>>>>>>>>>> thing that is likely to happen because of the other bug I reported.
> >>>>>>>>>>>
> >>>>>>>>>>> Speaking of it, does any of you have any suggestion on how to debug it?
> >>>>>>>>>> I was able to reproduce the initial issue by unloading hid-rmi and
> >>>>>>>>>> i2c-hid while holding my fingers on the touchpad. Mika's patch fixes it
> >>>>>>>>>> for me.
> >>>>>>>>>>
> >>>>>>>>>> For the original bug, you can modprobe i2c-hid debug=1 and we can see
> >>>>>>>>>> what data the touchpad is reporting. That might help narrowing down if
> >>>>>>>>>> it's noise which the touchpad thinks are fingers or if there is a
> >>>>>>>>>> problem with the I2C lines causing spurious interrupts.
> >>>>>>>>>>
> >>>>>>>>>> Andrew
> >>>>>>>>> I've already tried to do that and here what I got:
> >>>>>>>>>
> >>>>>>>>> When I release the finger, the last message is repeated 81 times.
> >>>>>>>>> If the byte containing informations about the width of the finger
> >>>>>>>>> becomes equal to either c0 or 0c at least once, the last message is
> >>>>>>>>> repeated indefinitely and changes as soon as I start using the touchpad.
> >>>>>>>>> The only way to stop it is to unload and reload i2c-hid.
> >>>>>>>> The reports before log throttling kicks in would still be useful. For
> >>>>>>>> instance c0 is outside of the range of finger width which we report so
> >>>>>>>> something is wrong there. But, the touchpad should stop interrupting
> >>>>>>>> once the finger is lifted. The fact that subsequent reads are reporting
> >>>>>>>> the same data does sound like a problem with I2C getting confused and
> >>>>>>>> continuously interrupting and reading the old finger data. I am also
> >>>>>>>> curious about the value of the byte after the report id.
> >>>>>>>>
> >>>>>>>> Andrew
> >>>>>>> If I'm not wrong c0 means that the width is 12 on y axis, while 0c means
> >>>>>>> that the width is 12 on the x axis.
> >>>>>> You are correct! I forgot width was 4 bits for X and Y in the same byte.
> >>>>>> That makes more sense.
> >>>>>>
> >>>>>>> I have to correct myself. The important thing is that the byte is either
> >>>>>>> cx or xc, where x is anything below c.
> >>>>>>>
> >>>>>>> Another correction. Sometimes unloading i2c-hid is not enough, I have to
> >>>>>>> first disable the touchpad with xinput and then unload i2c-hid. If I
> >>>>>>> don't do it, the messages starts reappearing as soon as I reload i2c-hid.
> >>>>>>>
> >>>>>>> I did several tests in the past months and I'm quite sure that the bug
> >>>>>>> happens only past xc/cy.
> >>>>>> This maybe coincidental. It is not obvious to me why a certain width
> >>>>>> value would cause the symptoms described.
> >>>>> Yes, I don't deny it. This is just a constant I found in my tests.
> >>>>>
> >>>>>>> Here few lines right before the bug. The last line is repeated indefinitely:
> >>>>>>>
> >>>>>>> [ 1983.527097] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 61 0a 5f 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.537211] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 63 0a 60 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.547329] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 64 0a 60 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.557486] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 66 0a 60 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.567663] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 67 5b 68 0a 60 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.577719] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 6a 0a 61 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.587852] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 67 5b 6b 0a 61 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.598001] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 67 5b 6e 0a 62 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.608215] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 68 5b 61 0a 62 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.618288] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 68 5b 64 0b 63 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.628493] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 68 5b 67 0b 63 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.638552] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 68 5b 69 0b 64 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.648663] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 68 5b 6c 0b 64 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.658789] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 68 5b 6f 0b 64 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.668923] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 61 0b 65 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.678819] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 64 0b 65 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.689230] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 66 0b 65 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.699435] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 69 5b 68 0b 65 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.709502] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 6a 0b 66 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.719574] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 6c 0b 66 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.729713] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 69 5b 6e 0b 66 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.739863] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6a 5b 60 0b 66 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.750001] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6a 5b 62 0b 66 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.760150] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6a 5b 64 0b 67 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.770291] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6a 5b 66 0b 67 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.780445] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6a 5b 68 0b 67 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.790490] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6a 5b 5a 0b 68 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.800667] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6a 5b 4e 0c 69 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.810691] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 31 0c 69 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.820963] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 24 0c 6a 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.831071] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 17 0c 6a 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.841178] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 09 0c 6a 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.851325] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 0b 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.861435] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6b 5b 0d 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.871566] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6b 5b 0f 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.881735] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 01 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.891975] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 03 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.902073] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 05 0c 6c 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.912155] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 07 0c 6b 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.922224] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 09 0c 6c 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.932364] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 0b 0c 6c 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.942480] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6c 5b 0d 0c 6c 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.952612] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6c 5b 0f 0c 6c 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.962774] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6d 5a f1 0d 6d 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.972932] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6d 5a f3 0d 6e 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.982872] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6d 5a f6 0d 6f 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1983.993194] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6d 5a f9 0d 6f 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.003295] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6d 5a fc 0d 6f 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.013511] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6d 5a ff 0d 70 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.023590] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6e 5a f2 0d 70 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.033747] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6e 5a f5 0e 71 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.043850] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6e 5a f8 0e 71 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.053873] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6e 5a fb 0e 71 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.064077] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6e 5a fe 0e 72 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.074207] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a f1 0e 72 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.084425] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 6f 5a f3 0e 72 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.094533] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a f6 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.104629] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a f8 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.114742] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a fa 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.124890] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a fc 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.135006] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 6f 5a fe 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.145149] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 70 5a f0 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.155317] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 70 5a e2 0e 73 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.165380] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 70 5a d4 0d 74 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.175532] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 70 5a d6 0d 74 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.185409] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 70 5a d8 0d 75 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.195761] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 70 5a db 0d 75 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.205909] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 70 5a dd 0d 75 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.216034] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 71 5a d0 0e 76 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.226198] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 71 5a d3 0e 77 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.236301] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 71 5a d6 0e 77 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.246520] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 71 5a cb 0f 79 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.256573] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 01 00 72 5a b1 0e 78 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.266697] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 72 5a a7 0e 77 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.276823] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 72 5a 6d 0d 72 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.286921] i2c_hid i2c-DLL060A:00: input: 20 00 0c 0c 01 00 73 59 96 0a 5a 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.296888] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 00 00 73 59 96 00 00 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.306825] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 00 00 73 59 96 00 00 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>>> [ 1984.316980] i2c_hid i2c-DLL060A:00: input: 20 00 0c 04 00 00 73 59 96 00 00 03 09 40 00 00 90 86 1d 00 00 00 00 00 00 00 00 00 00 00 00 00
> >>>>>> The last report which repeats indicates that no fingers are present.
> >>>>>> But, the click button is generating the interrupt and it is reporting
> >>>>>> that it is in the down position. Could the click button be getting stuck
> >>>>>> down? That would also explain why the data in the report is not
> >>>>>> changing. Could you be bumping the touchpad with your palm which is
> >>>>>> causing the click button to get stuck in the down position? That might
> >>>>>> also explain the large width value. Our max width is 15, so 12 would
> >>>>>> typically indicate a contact larger then a normal finger contact. That
> >>>>>> would explain the width of 12 showing up when this happens.
> >>>>> Yes, that's not a normal finger touch and the reported width seems
> >>>>> quite accurate to me. There are no clicks involved, laying the side of
> >>>>> my thumb gently on the top part of the clickpad (from where even voluntary
> >>>>> clicks are hard to obtain) is enough to trigger the bug. If a click is
> >>>>> reported, than something is really wrong.
> >>>> Do the reports look the same? With the repeated reports starting with
> >>>> "20 00 0c 04"?
> >>> I'm not sure I understood exactly what you want to know, so this might
> >>> not answer your questions.
> >>>
> >>> All the repeated messages look like this:
> >>>
> >>> 20 00 0c 04 00 00 27 57 fa 00 00 07 8a 0c 00 00 7e 87 eb 00 00 aa 8f 37 00 00 61 4d f1 00 00 00
> >>>
> >>> The values equal to zero are always equal to zero when there are no
> >>> fingers on the touchpad. The non-zero values are equal to the last
> >>> valid value recorded and don't change when the fingers are released.
> >>>
> >>> To get the above line I touched the touchpad with 5 fingers so that
> >>> all the bytes (except the last one which is different from zero on
> >>> click release) were used.
> >> Yes, that was the information I was looking for. But, this must not be
> >> my day since it turns out I misremembered what 0x4 stood for and this is
> >> unrelated to the click button. You can ignore everything I said about
> >> the click button =)
> >>
> >> The report you have above is actually a finger lift report which
> >> indicates that all of the fingers left the touchpad. I checked the
> >> firmware configuration for this touchpad and it will repeat the lift
> >> report probably about 40 times. This is the expected behavior. However,
> >> you reported earlier that the message had been repeated 81 times? That
> >> seems a bit high and it would not explain why it gets repeated indefinitely.
> >>
> >> You can try disabling the repeating finger lift reports and see if that
> >> helps. To do that you need to download a utility at:
> >> https://github.com/aduggan/rmi4utils
> >>
> >> After building it run:
> >> $ sudo ./rmihidtool -r 0x45 1 /dev/hidraw0
> >> This should print out 0x78 assuming the register address is what I
> >> expect. If not I can send further instructions on how to figure that out.
> >>
> >> To disable the repeating lift report run:
> >> $ sudo ./rmihidtool -w 0x45 0x38 /dev/hidraw0
> >>
> >> After you do that there should only be one finger lift report.
> > Yes, this disables the repeating lift report, but the bug is still there.
> 
> Ok, I would have been surprised if this fixed it. But, at least it helps 
> to narrow down the cause.
> 
> >
> >> Also, if you can get the firmware id from your touchpad that would also
> >> be useful.
> >>
> >> $ sudo ./rmihidtool -f /dev/hidraw0
> > firmware id: 1522295
> Thanks, I will see if I can get any additional information on this.
> 
> Andrew

Hi,

I think I found the source of the problem.

$ ./rmihidtool /dev/hidraw1 -r 0x50 1
0x01  #PalmDetect Interrupt Enable, right?
$ ./rmihidtool /dev/hidraw1 -w 0x50 0  #Disable PalmDetect Interrupt

It makes more sense now that widths greater than 12 trigger the bug.

Gabriele

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