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From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
To: Jiada Wang <jiada_wang@mentor.com>
Cc: nick@shmanahar.org, linux-input@vger.kernel.org,
	linux-kernel@vger.kernel.org, george_davis@mentor.com
Subject: Re: [PATCH v1 03/63] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary
Date: Wed, 21 Aug 2019 10:54:22 -0700	[thread overview]
Message-ID: <20190821175422.GE76194@dtor-ws> (raw)
In-Reply-To: <558e1227-7671-0838-d4e0-f234833c0973@mentor.com>

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 <nick.dyer@itdev.co.uk>
> > > 
> > > 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... 

Thanks.

-- 
Dmitry

  reply	other threads:[~2019-08-21 17:54 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-16  8:28 [PATCH v1 00/63] atmel_mxt_ts misc Jiada Wang
2019-08-16  8:28 ` Jiada Wang
2019-08-16  8:28 ` [PATCH v1 01/63] Input: introduce input_mt_report_slot_inactive Jiada Wang
2019-08-16  8:28   ` Jiada Wang
2019-08-16 17:12   ` Dmitry Torokhov
2019-08-21  9:13     ` Jiada Wang
2019-08-21  9:13       ` Jiada Wang
2019-08-16  8:28 ` [PATCH v1 02/63] Input: atmel_mxt_ts - rework sysfs init/remove Jiada Wang
2019-08-16  8:28   ` Jiada Wang
2019-08-16  8:28 ` [PATCH v1 03/63] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary Jiada Wang
2019-08-16  8:28   ` Jiada Wang
2019-08-16 17:16   ` Dmitry Torokhov
2019-08-21 13:26     ` Jiada Wang
2019-08-21 13:26       ` Jiada Wang
2019-08-21 17:54       ` Dmitry Torokhov [this message]
2019-08-22  3:37         ` Jiada Wang
2019-08-22  3:37           ` Jiada Wang
2019-08-16  8:28 ` [PATCH v1 04/63] Input: atmel_mxt_ts - split large i2c transfers into blocks Jiada Wang
2019-08-16  8:28   ` Jiada Wang
2019-08-16 17:18   ` Dmitry Torokhov
2019-08-22  5:24     ` Jiada Wang
2019-08-22  5:24       ` Jiada Wang
2019-08-16 17:32 ` [PATCH v1 00/63] atmel_mxt_ts misc Dmitry Torokhov
2019-08-19  9:29   ` Jiada Wang
2019-08-19  9:29     ` Jiada Wang

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