[PATCH 1/3] Input: atmel_mxt_ts - Make wait-after-reset period compatible with all chips

[PATCH 1/3] Input: atmel_mxt_ts - Make wait-after-reset period compatible with all chips

[Iiro Valkonen]

The delay before the chip can be accessed after reset varies between different
chips in maXTouch family. Waiting for 200ms and then monitoring the CHG (chip
is ready when the line is low) is guaranteed to work with all chips.

Signed-off-by: Iiro Valkonen <iiro.valkonen@atmel.com>
---
 drivers/input/touchscreen/atmel_mxt_ts.c |    4 +++-
 include/linux/i2c/atmel_mxt_ts.h         |    1 +
 2 files changed, 4 insertions(+), 1 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 1e61387..8870e7b 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -170,7 +170,7 @@
 #define MXT_BOOT_VALUE		0xa5
 #define MXT_BACKUP_VALUE	0x55
 #define MXT_BACKUP_TIME		25	/* msec */
-#define MXT_RESET_TIME		65	/* msec */
+#define MXT_RESET_TIME		200	/* msec */
 
 #define MXT_FWRESET_TIME	175	/* msec */
 
@@ -828,6 +828,8 @@ static int mxt_initialize(struct mxt_data *data)
 	mxt_write_object(data, MXT_GEN_COMMAND,
 			MXT_COMMAND_RESET, 1);
 	msleep(MXT_RESET_TIME);
+	while (data->pdata->read_chg())
+		msleep(2);
 
 	/* Update matrix size at info struct */
 	error = mxt_read_reg(client, MXT_MATRIX_X_SIZE, &val);
diff --git a/include/linux/i2c/atmel_mxt_ts.h b/include/linux/i2c/atmel_mxt_ts.h
index f027f7a..ef59c22 100644
--- a/include/linux/i2c/atmel_mxt_ts.h
+++ b/include/linux/i2c/atmel_mxt_ts.h
@@ -39,6 +39,7 @@ struct mxt_platform_data {
 	unsigned int voltage;
 	unsigned char orient;
 	unsigned long irqflags;
+	u8(*read_chg) (void);
 };
 
 #endif /* __LINUX_ATMEL_MXT_TS_H */
-- 
1.7.0.4

Re: [PATCH 1/3] Input: atmel_mxt_ts - Make wait-after-reset period compatible with all chips

[Dmitry Torokhov]

On Mon, Jul 04, 2011 at 12:05:31PM +0300, Iiro Valkonen wrote:
> The delay before the chip can be accessed after reset varies between different
> chips in maXTouch family. Waiting for 200ms and then monitoring the CHG (chip
> is ready when the line is low) is guaranteed to work with all chips.
> 
> Signed-off-by: Iiro Valkonen <iiro.valkonen@atmel.com>
> ---
>  drivers/input/touchscreen/atmel_mxt_ts.c |    4 +++-
>  include/linux/i2c/atmel_mxt_ts.h         |    1 +
>  2 files changed, 4 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
> index 1e61387..8870e7b 100644
> --- a/drivers/input/touchscreen/atmel_mxt_ts.c
> +++ b/drivers/input/touchscreen/atmel_mxt_ts.c
> @@ -170,7 +170,7 @@
>  #define MXT_BOOT_VALUE		0xa5
>  #define MXT_BACKUP_VALUE	0x55
>  #define MXT_BACKUP_TIME		25	/* msec */
> -#define MXT_RESET_TIME		65	/* msec */
> +#define MXT_RESET_TIME		200	/* msec */
>  
>  #define MXT_FWRESET_TIME	175	/* msec */
>  
> @@ -828,6 +828,8 @@ static int mxt_initialize(struct mxt_data *data)
>  	mxt_write_object(data, MXT_GEN_COMMAND,
>  			MXT_COMMAND_RESET, 1);
>  	msleep(MXT_RESET_TIME);
> +	while (data->pdata->read_chg())
> +		msleep(2);

I would prefer if we did not wait indefinitely but timed out after
certain number of retries.

Thanks.

-- 
Dmitry

Re: [PATCH 1/3] Input: atmel_mxt_ts - Make wait-after-reset period compatible with all chips

[Iiro Valkonen]

On 07/04/2011 01:04 PM, Dmitry Torokhov wrote:
>>  
>> @@ -828,6 +828,8 @@ static int mxt_initialize(struct mxt_data *data)
>>  	mxt_write_object(data, MXT_GEN_COMMAND,
>>  			MXT_COMMAND_RESET, 1);
>>  	msleep(MXT_RESET_TIME);
>> +	while (data->pdata->read_chg())
>> +		msleep(2);
> 
> I would prefer if we did not wait indefinitely but timed out after
> certain number of retries.
> 

Thanks, that does make sense. I'll send a new version.


BR,

-- 
Iiro