linux-kernel - Re: [PATCHv2] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

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Message-ID: <20180509144032.kirx5rz4cbz6cl4l@earth.universe>
Date:   Wed, 9 May 2018 16:40:32 +0200
From:   Sebastian Reichel <sebastian.reichel@...labora.co.uk>
To:     Pavel Machek <pavel@....cz>
Cc:     Nick Dyer <nick@...anahar.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Ezequiel Garcia <ezequiel@...labora.com>, kernel@...labora.com
Subject: Re: [PATCHv2] Input: atmel_mxt_ts - fix reset-gpio for level based
 irqs

Hi,

On Wed, May 09, 2018 at 04:25:45PM +0200, Pavel Machek wrote:
> On Mon 2018-04-23 13:58:44, Sebastian Reichel wrote:
> > The current reset-gpio support triggers an interrupt storm on platforms
> > using the maxtouch with level based interrupt. The Motorola Droid 4,
> > which I used for some of the tests is not affected, since it uses a edge
> > based interrupt.
> > 
> > This change avoids the interrupt storm by enabling the device while its
> > interrupt is disabled. Afterwards we wait 100ms. This is important for
> > two reasons: The device is unresponsive for some time (~22ms for
> > mxt224E) and the CHG (interrupt) line is not working properly for 100ms.
> > We don't need to wait for any following interrupts, since the following
> > mxt_initialize() checks for bootloader mode anyways.
> > 
> > This fixes a boot issue on GE PPD (watchdog kills device due to
> > interrupt storm) and does not cause regression on Motorola Droid 4.
> 
> Out of curiosity, what is "GE PPD"?

PPD is a product from GE Healthcare to monitor vital biometric signals:

arch/arm/boot/dts/imx53-ppd.dts

> > Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@...labora.co.uk>
> 
> Reviewed-by: Pavel Machek <pavel@....cz>

Thanks,

-- Sebastian

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