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Subject: Re: [PATCH v5 2/3] HID: quirks: Refactor ELAN 400 and 401 handling
To:     Lee Jones <lee.jones@linaro.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Jeffrey Hugo <jeffrey.l.hugo@gmail.com>,
        benjamin.tissoires@redhat.com, jikos@kernel.org,
        bjorn.andersson@linaro.org, robh+dt@kernel.org,
        mark.rutland@arm.com, agross@kernel.org, david.brown@linaro.org,
        hdegoede@redhat.com, linux-input@vger.kernel.org,
        devicetree@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20190606161055.47089-1-jeffrey.l.hugo@gmail.com>
 <20190606161322.47192-1-jeffrey.l.hugo@gmail.com>
 <20190612003507.GG143729@dtor-ws>
 <2282f3e1-e76a-4fe7-d447-51d9a4bee2de@codeaurora.org>
 <20190612143715.GC4660@dell>
From:   Jeffrey Hugo <jhugo@codeaurora.org>
Message-ID: <77e54e66-c7c8-9fd3-995a-7633202bb81e@codeaurora.org>
Date:   Wed, 12 Jun 2019 08:48:33 -0600
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On 6/12/2019 8:37 AM, Lee Jones wrote:
> On Wed, 12 Jun 2019, Jeffrey Hugo wrote:
> 
>> On 6/11/2019 6:35 PM, Dmitry Torokhov wrote:
>>> On Thu, Jun 06, 2019 at 09:13:22AM -0700, Jeffrey Hugo wrote:
>>>> There needs to be coordination between hid-quirks and the elan_i2c driver
>>>> about which devices are handled by what drivers.  Currently, both use
>>>> whitelists, which results in valid devices being unhandled by default,
>>>> when they should not be rejected by hid-quirks.  This is quickly becoming
>>>> an issue.
>>>>
>>>> Since elan_i2c has a maintained whitelist of what devices it will handle,
>>>> use that to implement a blacklist in hid-quirks so that only the devices
>>>> that need to be handled by elan_i2c get rejected by hid-quirks, and
>>>> everything else is handled by default.  The downside is the whitelist and
>>>> blacklist need to be kept in sync.
>>>>
>>>> Suggested-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
>>>> Signed-off-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
>>>> ---
>>>>    drivers/hid/hid-quirks.c | 78 ++++++++++++++++++++++++++++++++++------
>>>>    1 file changed, 67 insertions(+), 11 deletions(-)
>>>>
>>>> diff --git a/drivers/hid/hid-quirks.c b/drivers/hid/hid-quirks.c
>>>> index e5ca6fe2ca57..edebd0700e3d 100644
>>>> --- a/drivers/hid/hid-quirks.c
>>>> +++ b/drivers/hid/hid-quirks.c
>>>> @@ -912,8 +912,66 @@ static const struct hid_device_id hid_mouse_ignore_list[] = {
>>>>    	{ }
>>>>    };
>>>> +/*
>>>> + * List of device names that elan_i2c is handling and HID should ignore.  Must
>>>> + * be kept in sync with elan_i2c
>>>> + */
>>>> +static const char *hid_elan_i2c_ignore[] = {
>>>
>>> If this is a copy of elan whitelist, then, if we do not want to bother
>>> with sharing it in object form (as a elan-i2c-ids module), can we at
>>> least move it into include/linux/input/elan-i2c-ids.h and consume from
>>> hid-quirks.c?
>>
>> I can put it in a shared header file, however elan-i2c and hid-quirks
>> would need to be updated in the same change to prevent a breakage, but
>> that would seem to violate a concern Benjamin brought up in v4 given
>> that elan-i2c is maintained in your input tree, and hid-quirks is
>> maintained in his hid tree.
>>
>> Are you ok with the elan-i2c changes going through Benjamin's hid tree?
> 
> We co-ordinate cross-subsystem merges all the time.  That is never a
> reason to not do the 'right thing (tm)'.  If this information can be
> held in a single, central place, without the need for constant
> re-alignment, I'm all for it.
> 

I'm aware coordination is a thing.  I'm trying to elicit some 
coordination between Dmitry and Benjamin.