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[109.252.192.57]) by smtp.googlemail.com with ESMTPSA id y23sm995881lfy.158.2021.01.22.12.10.52 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 22 Jan 2021 12:10:52 -0800 (PST) Subject: Re: [PATCH RESEND v8 2/4] input: elants: support old touch report format From: Dmitry Osipenko To: Dmitry Torokhov , =?UTF-8?B?TWljaGHFgiBNaXJvc8WCYXc=?= Cc: Johnny Chuang , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org References: <20201211160917.GA23095@qmqm.qmqm.pl> <3d872d19-a0b2-ed83-4b08-5c9a4755c2fe@gmail.com> <20201211170401.GA31605@qmqm.qmqm.pl> <79cf6571-4239-e98e-6001-70a4bf8b0fe5@gmail.com> Message-ID: <4c443c59-a7f8-bf16-cc0b-0e542c0d127f@gmail.com> Date: Fri, 22 Jan 2021 23:10:52 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.4.2 MIME-Version: 1.0 In-Reply-To: <79cf6571-4239-e98e-6001-70a4bf8b0fe5@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-input@vger.kernel.org 08.01.2021 01:06, Dmitry Osipenko пишет: > 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? > I'll make a v9 over this weekend. Michał, please let me know if you already started to work on this or have any objections.