linux-kernel - Re: [PATCH] Input: synaptics-rmi4 - Fix error handling in I2C transport driver

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Date:   Sat, 1 Oct 2016 10:45:16 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andrew Duggan <andrew@...gan.us>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Duggan <aduggan@...aptics.com>
Subject: Re: [PATCH] Input: synaptics-rmi4 - Fix error handling in I2C
 transport driver

On 10/01/2016 10:27 AM, Andrew Duggan wrote:
>
>
> On Fri, Sep 30, 2016, at 08:44 PM, Guenter Roeck wrote:
>> On 09/30/2016 04:02 PM, Dmitry Torokhov wrote:
>>> On Fri, Sep 30, 2016 at 03:54:03PM -0700, Dmitry Torokhov wrote:
>>>> On Thu, Sep 29, 2016 at 10:55:40AM -0700, Bjorn Andersson wrote:
>>>>> On Wed 28 Sep 17:37 PDT 2016, Guenter Roeck wrote:
>>>>>
>>>>>> Instantiating the rmi4 I2C transport driver without interrupts assigned
>>>>>> (for example using manual i2c instantiation from the command line)
>>>>>> caused the driver to fail to load, but it does not clean up its
>>>>>> regulator or transport device registrations. Result is a crash at a later
>>>>>> time, for example when rebooting the system.
>>>>>>
>>>>>> Fixes: 946c8432aab0 ("Input: synaptics-rmi4 - support regulator supplies")
>>>>>
>>>>> Sorry for that.
>>>>>
>>>>>> Fixes: fdf51604f104 ("Input: synaptics-rmi4 - add I2C transport driver")
>>>>>> Cc: Bjorn Andersson <bjorn.andersson@...aro.org>
>>>>>
>>>>> Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>
>>>>
>>>> Applied, thank you.
>>>
>>> I take it back. rmi_i2c_init_irq() uses devm* so this whole thing mixes
>>> up devm* and manual unregistering and unwind order is completely
>>> broken.
>>>
>> Oops ...
>>
>>> 1. Why do we register interrupt from transport drivers and not make it
>>> part of rmi_register_transport_device()?
>
> Not all RMI devices will have access to interrupts (ie HID and SMBus).
> The same goes for regulators. Here is a reference to a previous
> discussion regarding both:
> https://lkml.org/lkml/2016/5/9/1055
>
>>
>> rmi_register_transport_device() doesn't take dev as parameter.
>>
>>> 2. If we need to use some non-devm-ised resources we should use
>>> devm_add_action[_or_reset] to work these operations into devm stream.
>>
>
> Since the regulator functions have their own devm_ versions I would
> suggest switching to those functions to avoid dealing with
> unregistering.
>
Maybe I am missing something, but I don't see a devm_regulator_bulk_enable().
devm_regulator_bulk_get() is already used.

Guenter

> Registering and unregistering the transport device is a bit more
> complicated since these functions add and put the rmi_dev device. But,
> it sounds like we can handle the unregister using
> devm_add_action_or_reset().
>