[PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[Sebastian Reichel]

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 level
based interrupt.

This change avoids the interrupt storm by enabling the device while
its interrupt is disabled. The following mxt_initialize() requires,
that the device is responsive (at least mxt224E is unresponsive for
~22ms), so we wait some time. We don't wait for leaving bootloader
mode anymore, since mxt_initialize() checks for it anyways.

This fixes a boot problem on GE PPD (watchdog kills device) and also
has been tested on the Droid 4.

Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 5d9699fe1b55..f8a9f2a47e78 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -194,6 +194,7 @@ enum t100_type {
 
 /* Delay times */
 #define MXT_BACKUP_TIME		50	/* msec */
+#define MXT_RESET_GPIO_TIME	20	/* msec */
 #define MXT_RESET_TIME		200	/* msec */
 #define MXT_RESET_TIMEOUT	3000	/* msec */
 #define MXT_CRC_TIMEOUT		1000	/* msec */
@@ -3167,20 +3168,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		return error;
 	}
 
+	disable_irq(client->irq);
+
 	if (data->reset_gpio) {
-		data->in_bootloader = true;
-		msleep(MXT_RESET_TIME);
-		reinit_completion(&data->bl_completion);
+		msleep(MXT_RESET_GPIO_TIME);
 		gpiod_set_value(data->reset_gpio, 1);
-		error = mxt_wait_for_completion(data, &data->bl_completion,
-						MXT_RESET_TIMEOUT);
-		if (error)
-			return error;
-		data->in_bootloader = false;
+		msleep(MXT_RESET_TIME);
 	}
 
-	disable_irq(client->irq);
-
 	error = mxt_initialize(data);
 	if (error)
 		return error;
-- 
2.17.0

Re: [PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[Ezequiel Garcia]

Hi Sebastian,

On Fri, 2018-04-20 at 19:24 +0200, 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 level
> based interrupt.
> 

I found this confusing. Interrupt storm happen with level-based interrupts,
but the Droid4 is not affected?

> This change avoids the interrupt storm by enabling the device while
> its interrupt is disabled. The following mxt_initialize() requires,
> that the device is responsive (at least mxt224E is unresponsive for
> ~22ms), so we wait some time. We don't wait for leaving bootloader
> mode anymore, since mxt_initialize() checks for it anyways.
> 

IMHO, having some more or less arbritrary sleeps is almost
always a problem. This value might be enough for some platform,
might be too short for some other, and then it might get too large
for someone else.

> This fixes a boot problem on GE PPD (watchdog kills device) and also
> has been tested on the Droid 4.
> 
> Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 5d9699fe1b55..f8a9f2a47e78 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -194,6 +194,7 @@ enum t100_type {
>  
>  /* Delay times */
>  #define MXT_BACKUP_TIME		50	/* msec */
> +#define MXT_RESET_GPIO_TIME	20	/* msec */
>  #define MXT_RESET_TIME		200	/* msec */
>  #define MXT_RESET_TIMEOUT	3000	/* msec */
>  #define MXT_CRC_TIMEOUT		1000	/* msec */
> @@ -3167,20 +3168,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		return error;
>  	}
>  
> +	disable_irq(client->irq);
> +
>  	if (data->reset_gpio) {
> -		data->in_bootloader = true;
> -		msleep(MXT_RESET_TIME);
> -		reinit_completion(&data->bl_completion);
> +		msleep(MXT_RESET_GPIO_TIME);
>  		gpiod_set_value(data->reset_gpio, 1);

Can't we enable the IRQ here, just before the wait...

> -		error = mxt_wait_for_completion(data, &data->bl_completion,
> -						MXT_RESET_TIMEOUT);

... and then disable it back afterwards?

> -		if (error)
> -			return error;
> -		data->in_bootloader = false;
> +		msleep(MXT_RESET_TIME);

>  	}
>  
> -	disable_irq(client->irq);
> -
>  	error = mxt_initialize(data);
>  	if (error)
>  		return error;
> -- 
> 2.17.0
> 
> 

Re: [PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[Sebastian Reichel]

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On Fri, Apr 20, 2018 at 02:44:02PM -0300, Ezequiel Garcia wrote:
> Hi Sebastian,
> 
> On Fri, 2018-04-20 at 19:24 +0200, 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 level
> > based interrupt.
> > 
> 
> I found this confusing. Interrupt storm happen with level-based interrupts,
> but the Droid4 is not affected?

This is a typo. Droid 4 has an edge based interrupt defined, PPD has
an level based interrupt defined. PPD got an interrupt storm, Droid 4
did not.

> > This change avoids the interrupt storm by enabling the device while
> > its interrupt is disabled. The following mxt_initialize() requires,
> > that the device is responsive (at least mxt224E is unresponsive for
> > ~22ms), so we wait some time. We don't wait for leaving bootloader
> > mode anymore, since mxt_initialize() checks for it anyways.
> > 
> 
> IMHO, having some more or less arbritrary sleeps is almost
> always a problem. This value might be enough for some platform,
> might be too short for some other, and then it might get too large
> for someone else.

The 22ms chip-being-unresponsive are not newly introduced. The
same 22ms are also required for soft-reset. I did introduce a
new time (MXT_RESET_GPIO_TIME) for the "chip being reset" state,
since my randomly chosen 200ms from before were exaggerated
considering all mxt datasheets I checked stated only a few nano
seconds.

> > This fixes a boot problem on GE PPD (watchdog kills device) and also
> > has been tested on the Droid 4.
> > 
> > Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> > ---
> >  drivers/input/touchscreen/atmel_mxt_ts.c | 15 +++++----------
> >  1 file changed, 5 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> > index 5d9699fe1b55..f8a9f2a47e78 100644
> > --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> > +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> > @@ -194,6 +194,7 @@ enum t100_type {
> >  
> >  /* Delay times */
> >  #define MXT_BACKUP_TIME		50	/* msec */
> > +#define MXT_RESET_GPIO_TIME	20	/* msec */
> >  #define MXT_RESET_TIME		200	/* msec */
> >  #define MXT_RESET_TIMEOUT	3000	/* msec */
> >  #define MXT_CRC_TIMEOUT		1000	/* msec */
> > @@ -3167,20 +3168,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
> >  		return error;
> >  	}
> >  
> > +	disable_irq(client->irq);
> > +
> >  	if (data->reset_gpio) {
> > -		data->in_bootloader = true;
> > -		msleep(MXT_RESET_TIME);
> > -		reinit_completion(&data->bl_completion);
> > +		msleep(MXT_RESET_GPIO_TIME);
> >  		gpiod_set_value(data->reset_gpio, 1);
> 
> Can't we enable the IRQ here, just before the wait...
> 
> > -		error = mxt_wait_for_completion(data, &data->bl_completion,
> > -						MXT_RESET_TIMEOUT);
> 
> ... and then disable it back afterwards?

Yes and no. We need the wait, since the interrupt pin does random
stuff for 100ms after reset. We can do the wait-for-completion
after that time (see mxt_soft_reset function). I kept it simple,
since the following init does another soft reset anyways.

> > -		if (error)
> > -			return error;
> > -		data->in_bootloader = false;
> > +		msleep(MXT_RESET_TIME);
> 
> >  	}
> >  
> > -	disable_irq(client->irq);
> > -
> >  	error = mxt_initialize(data);
> >  	if (error)
> >  		return error;

-- Sebastian

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Re: [PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[Nick Dyer]

On Fri, Apr 20, 2018 at 09:42:07PM +0200, Sebastian Reichel wrote:
> On Fri, Apr 20, 2018 at 02:44:02PM -0300, Ezequiel Garcia wrote:
> > Hi Sebastian,
> > 
> > On Fri, 2018-04-20 at 19:24 +0200, 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 level
> > > based interrupt.
> > > 
> > 
> > I found this confusing. Interrupt storm happen with level-based interrupts,
> > but the Droid4 is not affected?

Can I ask what happens during the interrupt storm. Are you getting lots
of the "failed to read T44 and T5" message, or something else?

> > > This change avoids the interrupt storm by enabling the device while
> > > its interrupt is disabled. The following mxt_initialize() requires,
> > > that the device is responsive (at least mxt224E is unresponsive for
> > > ~22ms), so we wait some time. We don't wait for leaving bootloader
> > > mode anymore, since mxt_initialize() checks for it anyways.
> > > 
> > 
> > IMHO, having some more or less arbritrary sleeps is almost
> > always a problem. This value might be enough for some platform,
> > might be too short for some other, and then it might get too large
> > for someone else.
> 
> The 22ms chip-being-unresponsive are not newly introduced. The
> same 22ms are also required for soft-reset. I did introduce a
> new time (MXT_RESET_GPIO_TIME) for the "chip being reset" state,
> since my randomly chosen 200ms from before were exaggerated
> considering all mxt datasheets I checked stated only a few nano
> seconds.

According to the data sheets there is a period after a reset where the
CHG line is temporarily set as an input, during which the host should
ignore it. If you don't, you might get a stray interrupt and try and
communicate with the device, which might leave it in a bad state. I
think you mentioned that later in your email.

The reset time varies per chip, but the 100ms in mxt_soft_reset() was
based on discussions with app support at Atmel, so should be correct in
most cases.

Re: [PATCH] Input: atmel_mxt_ts - fix reset-gpio for level based irqs

[Sebastian Reichel]

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Hi,

On Sat, Apr 21, 2018 at 09:11:37PM +0100, Nick Dyer wrote:
> On Fri, Apr 20, 2018 at 09:42:07PM +0200, Sebastian Reichel wrote:
> > On Fri, Apr 20, 2018 at 02:44:02PM -0300, Ezequiel Garcia wrote:
> > > Hi Sebastian,
> > > 
> > > On Fri, 2018-04-20 at 19:24 +0200, 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 level
> > > > based interrupt.
> > > > 
> > > 
> > > I found this confusing. Interrupt storm happen with level-based interrupts,
> > > but the Droid4 is not affected?
> 
> Can I ask what happens during the interrupt storm. Are you getting lots
> of the "failed to read T44 and T5" message, or something else?

I don't get any message (with DEBUG enabled for the driver).
The boot process hangs and after a few seconds the watchdog kicks in.

> > > > This change avoids the interrupt storm by enabling the device while
> > > > its interrupt is disabled. The following mxt_initialize() requires,
> > > > that the device is responsive (at least mxt224E is unresponsive for
> > > > ~22ms), so we wait some time. We don't wait for leaving bootloader
> > > > mode anymore, since mxt_initialize() checks for it anyways.
> > > > 
> > > 
> > > IMHO, having some more or less arbritrary sleeps is almost
> > > always a problem. This value might be enough for some platform,
> > > might be too short for some other, and then it might get too large
> > > for someone else.
> > 
> > The 22ms chip-being-unresponsive are not newly introduced. The
> > same 22ms are also required for soft-reset. I did introduce a
> > new time (MXT_RESET_GPIO_TIME) for the "chip being reset" state,
> > since my randomly chosen 200ms from before were exaggerated
> > considering all mxt datasheets I checked stated only a few nano
> > seconds.
> 
> According to the data sheets there is a period after a reset where the
> CHG line is temporarily set as an input, during which the host should
> ignore it. If you don't, you might get a stray interrupt and try and
> communicate with the device, which might leave it in a bad state. I
> think you mentioned that later in your email.
> 
> The reset time varies per chip, but the 100ms in mxt_soft_reset() was
> based on discussions with app support at Atmel, so should be correct in
> most cases.

Right. This sleep time is missing for the gpio based reset. The
other checks are not required, since the chip initialization
routine is called directly afterwards. I will send a PATCHv2,
that fixes the patch description and uses the same timeout value
for both resets.

-- Sebastian

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

[Sebastian Reichel]

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.

Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
---
Changes since PATCHv2:
 * fix patch description
 * use same timeout value for soft and gpio-reset
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 5d9699fe1b55..f97fbb0af020 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -194,6 +194,8 @@ enum t100_type {
 
 /* Delay times */
 #define MXT_BACKUP_TIME		50	/* msec */
+#define MXT_RESET_GPIO_TIME	20	/* msec */
+#define MXT_RESET_INVALID_CHG	100	/* msec */
 #define MXT_RESET_TIME		200	/* msec */
 #define MXT_RESET_TIMEOUT	3000	/* msec */
 #define MXT_CRC_TIMEOUT		1000	/* msec */
@@ -1206,7 +1208,7 @@ static int mxt_soft_reset(struct mxt_data *data)
 		return ret;
 
 	/* Ignore CHG line for 100ms after reset */
-	msleep(100);
+	msleep(MXT_RESET_INVALID_CHG);
 
 	mxt_acquire_irq(data);
 
@@ -3167,20 +3169,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		return error;
 	}
 
+	disable_irq(client->irq);
+
 	if (data->reset_gpio) {
-		data->in_bootloader = true;
-		msleep(MXT_RESET_TIME);
-		reinit_completion(&data->bl_completion);
+		msleep(MXT_RESET_GPIO_TIME);
 		gpiod_set_value(data->reset_gpio, 1);
-		error = mxt_wait_for_completion(data, &data->bl_completion,
-						MXT_RESET_TIMEOUT);
-		if (error)
-			return error;
-		data->in_bootloader = false;
+		msleep(MXT_RESET_INVALID_CHG);
 	}
 
-	disable_irq(client->irq);
-
 	error = mxt_initialize(data);
 	if (error)
 		return error;
-- 
2.17.0

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

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 2874 bytes --]

Hi,

On Mon, Apr 23, 2018 at 01:58:44PM +0200, 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.
> 
> Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
> ---
> Changes since PATCHv2:
>  * fix patch description
>  * use same timeout value for soft and gpio-reset
> ---

ping.

-- Sebastian

>  drivers/input/touchscreen/atmel_mxt_ts.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 5d9699fe1b55..f97fbb0af020 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -194,6 +194,8 @@ enum t100_type {
>  
>  /* Delay times */
>  #define MXT_BACKUP_TIME		50	/* msec */
> +#define MXT_RESET_GPIO_TIME	20	/* msec */
> +#define MXT_RESET_INVALID_CHG	100	/* msec */
>  #define MXT_RESET_TIME		200	/* msec */
>  #define MXT_RESET_TIMEOUT	3000	/* msec */
>  #define MXT_CRC_TIMEOUT		1000	/* msec */
> @@ -1206,7 +1208,7 @@ static int mxt_soft_reset(struct mxt_data *data)
>  		return ret;
>  
>  	/* Ignore CHG line for 100ms after reset */
> -	msleep(100);
> +	msleep(MXT_RESET_INVALID_CHG);
>  
>  	mxt_acquire_irq(data);
>  
> @@ -3167,20 +3169,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		return error;
>  	}
>  
> +	disable_irq(client->irq);
> +
>  	if (data->reset_gpio) {
> -		data->in_bootloader = true;
> -		msleep(MXT_RESET_TIME);
> -		reinit_completion(&data->bl_completion);
> +		msleep(MXT_RESET_GPIO_TIME);
>  		gpiod_set_value(data->reset_gpio, 1);
> -		error = mxt_wait_for_completion(data, &data->bl_completion,
> -						MXT_RESET_TIMEOUT);
> -		if (error)
> -			return error;
> -		data->in_bootloader = false;
> +		msleep(MXT_RESET_INVALID_CHG);
>  	}
>  
> -	disable_irq(client->irq);
> -
>  	error = mxt_initialize(data);
>  	if (error)
>  		return error;
> -- 
> 2.17.0
> 

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

[Pavel Machek]

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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"?

> Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

Reviewed-by: Pavel Machek <pavel@ucw.cz>

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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

[Sebastian Reichel]

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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@collabora.co.uk>
> 
> Reviewed-by: Pavel Machek <pavel@ucw.cz>

Thanks,

-- Sebastian

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

[Dmitry Torokhov]

On Mon, Apr 23, 2018 at 01:58:44PM +0200, 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.
> 
> Fixes: f657b00df22e ("Input: atmel_mxt_ts - add support for reset line")
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>

Applied, thank you.

> ---
> Changes since PATCHv2:
>  * fix patch description
>  * use same timeout value for soft and gpio-reset
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c | 18 +++++++-----------
>  1 file changed, 7 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 5d9699fe1b55..f97fbb0af020 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -194,6 +194,8 @@ enum t100_type {
>  
>  /* Delay times */
>  #define MXT_BACKUP_TIME		50	/* msec */
> +#define MXT_RESET_GPIO_TIME	20	/* msec */
> +#define MXT_RESET_INVALID_CHG	100	/* msec */
>  #define MXT_RESET_TIME		200	/* msec */
>  #define MXT_RESET_TIMEOUT	3000	/* msec */
>  #define MXT_CRC_TIMEOUT		1000	/* msec */
> @@ -1206,7 +1208,7 @@ static int mxt_soft_reset(struct mxt_data *data)
>  		return ret;
>  
>  	/* Ignore CHG line for 100ms after reset */
> -	msleep(100);
> +	msleep(MXT_RESET_INVALID_CHG);
>  
>  	mxt_acquire_irq(data);
>  
> @@ -3167,20 +3169,14 @@ static int mxt_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  		return error;
>  	}
>  
> +	disable_irq(client->irq);
> +
>  	if (data->reset_gpio) {
> -		data->in_bootloader = true;
> -		msleep(MXT_RESET_TIME);
> -		reinit_completion(&data->bl_completion);
> +		msleep(MXT_RESET_GPIO_TIME);
>  		gpiod_set_value(data->reset_gpio, 1);
> -		error = mxt_wait_for_completion(data, &data->bl_completion,
> -						MXT_RESET_TIMEOUT);
> -		if (error)
> -			return error;
> -		data->in_bootloader = false;
> +		msleep(MXT_RESET_INVALID_CHG);
>  	}
>  
> -	disable_irq(client->irq);
> -
>  	error = mxt_initialize(data);
>  	if (error)
>  		return error;
> -- 
> 2.17.0
> 

-- 
Dmitry