From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiada Wang Subject: Re: [PATCH v1 03/63] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary Date: Thu, 22 Aug 2019 12:37:12 +0900 Message-ID: References: <20190816082952.17985-1-jiada_wang@mentor.com> <20190816082952.17985-4-jiada_wang@mentor.com> <20190816171622.GF121898@dtor-ws> <558e1227-7671-0838-d4e0-f234833c0973@mentor.com> <20190821175422.GE76194@dtor-ws> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190821175422.GE76194@dtor-ws> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Dmitry Torokhov Cc: nick@shmanahar.org, linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, george_davis@mentor.com List-Id: linux-input@vger.kernel.org Hi On 2019/08/22 2:54, Dmitry Torokhov wrote: > On Wed, Aug 21, 2019 at 10:26:31PM +0900, Jiada Wang wrote: >> Hi Dmitry >> >> On 2019/08/17 2:16, Dmitry Torokhov wrote: >>> On Fri, Aug 16, 2019 at 05:28:52PM +0900, Jiada Wang wrote: >>>> From: Nick Dyer >>>> >>>> The workaround of reading all messages until an invalid is received is a >>>> way of forcing the CHG line high, which means that when using >>>> edge-triggered interrupts the interrupt can be acquired. >>>> >>>> With level-triggered interrupts the workaround is unnecessary. >>>> >>>> Also, most recent maXTouch chips have a feature called RETRIGEN which, when >>>> enabled, reasserts the interrupt line every cycle if there are messages >>>> waiting. This also makes the workaround unnecessary. >>>> >>>> Note: the RETRIGEN feature is only in some firmware versions/chips, it's >>>> not valid simply to enable the bit. >>> >>> Instead of trying to work around of misconfiguration for IRQ/firmware, >>> can we simply error out of probe if we see a level interrupt with >>> !RETRIGEN firmware? >>> >> I think for old firmwares, which doesn't support RETRIGEN feature, this >> workaround is needed, otherwise we will break all old firmwares, which >> configured with edge-triggered IRQ > > Do you know if there are any? I know Chrome OS firmware have RETRIGEN > activated and they are pretty old (original Pixel is from 2013). But if > we indeed have devices with edge interrupt and old not firmware that > does not retrigger, I guess we'll have to keep it... > Honestly I don't know firmwares/chips which don't support RETRIGEN feature. BUT Dyer originally authored this patch in 2012, I assume here "old" firmware/chips means, those before 2012. Thanks, Jiada > Thanks. >