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From: Dmitry Osipenko <digetx@gmail.com>
To: "Dmitry Torokhov" <dmitry.torokhov@gmail.com>,
	"Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Cc: Johnny Chuang <johnny.chuang.emc@gmail.com>,
	linux-input@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH RESEND v8 2/4] input: elants: support old touch report format
Date: Fri, 8 Jan 2021 01:06:59 +0300	[thread overview]
Message-ID: <79cf6571-4239-e98e-6001-70a4bf8b0fe5@gmail.com> (raw)
In-Reply-To: <X9O/F0M4rU6cBdRi@google.com>

11.12.2020 21:48, Dmitry Torokhov пишет:
> On Fri, Dec 11, 2020 at 06:04:01PM +0100, Michał Mirosław wrote:
>> On Fri, Dec 11, 2020 at 07:39:33PM +0300, Dmitry Osipenko wrote:
>>> 11.12.2020 19:09, Michał Mirosław пишет:
>>>> On Thu, Dec 10, 2020 at 11:29:40PM -0800, Dmitry Torokhov wrote:
>>>>> Hi Michał,
>>>>> On Fri, Dec 11, 2020 at 07:53:56AM +0100, Michał Mirosław wrote:
>>>>>> @@ -998,17 +1011,18 @@ static irqreturn_t elants_i2c_irq(int irq, void *_dev)
>>>>>>  			}
>>>>>>  
>>>>>>  			report_len = ts->buf[FW_HDR_LENGTH] / report_count;
>>>>>> -			if (report_len != PACKET_SIZE) {
>>>>>> +			if (report_len != PACKET_SIZE &&
>>>>>> +			    report_len != PACKET_SIZE_OLD) {
>>>>>>  				dev_err(&client->dev,
>>>>>> -					"mismatching report length: %*ph\n",
>>>>>> +					"unsupported report length: %*ph\n",
>>>>>>  					HEADER_SIZE, ts->buf);
>>>>> Do I understand this correctly that the old packets are only observed on
>>>>> EKTF3624? If so can we expand the check so that we only accept packets
>>>>> with "old" size when we know we are dealing with this device?
>>>>
>>>> We only have EKTF3624 and can't be sure there are no other chips needing this.
>>>
>>> In practice this older packet format should be seen only on 3624, but
>>> nevertheless we could make it more explicit by adding the extra chip_id
>>> checks.
>>>
>>> It won't be difficult to change it in the future if will be needed.
>>>
>>> I think the main point that Dmitry Torokhov conveys here is that we
>>> should minimize the possible impact on the current EKT3500 code since we
>>> don't have definitive answers regarding the firmware differences among
>>> the hardware variants.
>>
>> The only possible impact here is that older firmware instead of breaking
>> would suddenly work. Maybe we can accept such a risk?
> 
> These are not controllers we'll randomly find in devices: Windows boxes
> use I2C HID, Chrome devices use "new" firmware, so that leaves random
> ARM where someone needs to consciously add proper compatible before the
> driver will engage with the controller.
> 
> I would prefer we were conservative and not accept potentially invalid
> data.
> 
> Thanks.
> 

Michał, will you be able to make v9 with all the review comments addressed?

  reply	other threads:[~2021-01-07 22:07 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-12-11  6:53 [PATCH RESEND v8 0/4] input: elants: Support Asus TF300T and Nexus 7 touchscreens Michał Mirosław
2020-12-11  6:53 ` [PATCH RESEND v8 2/4] input: elants: support old touch report format Michał Mirosław
2020-12-11  7:29   ` Dmitry Torokhov
2020-12-11 16:09     ` Michał Mirosław
2020-12-11 16:39       ` Dmitry Osipenko
2020-12-11 17:04         ` Michał Mirosław
2020-12-11 18:48           ` Dmitry Torokhov
2021-01-07 22:06             ` Dmitry Osipenko [this message]
2021-01-22 20:10               ` Dmitry Osipenko
2021-01-22 22:37                 ` Michał Mirosław
2021-01-23 14:07                   ` Dmitry Osipenko
2020-12-11  6:53 ` [PATCH RESEND v8 1/4] input: elants: document some registers and values Michał Mirosław
2020-12-11  7:11   ` Dmitry Torokhov
2020-12-11  6:53 ` [PATCH RESEND v8 3/4] input: elants: read touchscreen size for EKTF3624 Michał Mirosław
2020-12-11  7:22   ` Dmitry Torokhov
2020-12-11 16:38     ` Michał Mirosław
2020-12-11  6:53 ` [PATCH RESEND v8 4/4] input: elants: support 0x66 reply opcode for reporting touches Michał Mirosław
2020-12-11  7:36   ` Dmitry Torokhov
  -- strict thread matches above, loose matches on Subject: below --
2020-11-09 17:28 [PATCH RESEND v8 0/4] input: elants: Support Asus TF300T and Nexus 7 touchscreens Michał Mirosław
2020-11-09 17:28 ` [PATCH RESEND v8 2/4] input: elants: support old touch report format Michał Mirosław

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