Re: [PATCH v1 03/63] Input: atmel_mxt_ts - only read messages in mxt_acquire_irq() when necessary

[Jiada Wang]

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 <nick.dyer@xxxxxxxxxxx>
> > > >
> > > > 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.