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@xxxxxxxxxxxxxxx>
> ---
> 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
>
>
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