[PATCH] Input: elants_i2c - Fix sw reset delays

We only need to wait 10ms instead of 30ms before starting fastboot or
sending IAP on the touchscreen. Also, instead of delaying everytime
sw_reset is called, this delays 10ms in the function that starts
fastboot. There's also an explicit 20ms delay before sending IAP when
updating the firmware, so no additional delay is needed there. This
change also has the benefit of not delaying when wakeup is enabled
during suspend. This is because sw_reset is called, yet fastboot
isn't.

Change-Id: I9e3019720186ba0023891fafeb4fe3d2510e454b
Signed-off-by: Derek Basehore <redacted>
---
 drivers/input/touchscreen/elants_i2c.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index d21ca39b0fdb..18ce04ba0173 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c

@@ -284,12 +284,6 @@ static int elants_i2c_sw_reset(struct i2c_client *client)
 		return error;
 	}
 
-	/*
-	 * We should wait at least 10 msec (but no more than 40) before
-	 * sending fastboot or IAP command to the device.
-	 */
-	msleep(30);
-
 	return 0;
 }
 

@@ -500,6 +494,12 @@ static int elants_i2c_fastboot(struct i2c_client *client)
 	const u8 boot_cmd[] = { 0x4D, 0x61, 0x69, 0x6E };
 	int error;
 
+	/*
+	 * We should wait at least 10 msec (but no more than 40) before sending
+	 * fastboot command to the device.
+	 */
+	usleep_range(10 * 1000, 11 * 1000);
+
 	error = elants_i2c_send(client, boot_cmd, sizeof(boot_cmd));
 	if (error) {
 		dev_err(&client->dev, "boot failed: %d\n", error);

@@ -643,6 +643,10 @@ static int elants_i2c_do_update_firmware(struct i2c_client *client,
 			dev_err(&client->dev, "Failed close idle: %d\n", error);
 		msleep(60);
 		elants_i2c_sw_reset(client);
+		/*
+		 * We should wait at least 10 msec (but no more than 40) before
+		 * sending IAP command to the device.
+		 */
 		msleep(20);
 		error = elants_i2c_send(client, enter_iap, sizeof(enter_iap));
 	}

-- 
2.19.0.rc0.228.g281dcd1b4d0-goog

Hi Derek,

On Thu, Aug 23, 2018 at 04:10:13PM -0700, Derek Basehore wrote:

We only need to wait 10ms instead of 30ms before starting fastboot or
sending IAP on the touchscreen. Also, instead of delaying everytime
sw_reset is called, this delays 10ms in the function that starts
fastboot. There's also an explicit 20ms delay before sending IAP when
updating the firmware, so no additional delay is needed there. This
change also has the benefit of not delaying when wakeup is enabled
during suspend. This is because sw_reset is called, yet fastboot
isn't.

Change-Id: I9e3019720186ba0023891fafeb4fe3d2510e454b

This is not needed ;)

So the original comment was talking about timing on fastboot or IAP
command, but the original code had 50 msec wait here (30 from
elants_i2c_sw_reset plus the 20), thus already violating 40 msec rule
for IAP. Unless Elan folks can confirm it is OK to reduce the wait here
I'd prefer we kept it at 50. Firmware update is does not happen that
often anyway.

Thanks.

-- 
Dmitry

Let's add Elan folks to the discussion.

On Thu, Aug 23, 2018 at 04:30:28PM -0700, Dmitry Torokhov wrote:

Hi Derek,

On Thu, Aug 23, 2018 at 04:10:13PM -0700, Derek Basehore wrote:

quoted

We only need to wait 10ms instead of 30ms before starting fastboot or
sending IAP on the touchscreen. Also, instead of delaying everytime
sw_reset is called, this delays 10ms in the function that starts
fastboot. There's also an explicit 20ms delay before sending IAP when
updating the firmware, so no additional delay is needed there. This
change also has the benefit of not delaying when wakeup is enabled
during suspend. This is because sw_reset is called, yet fastboot
isn't.

Change-Id: I9e3019720186ba0023891fafeb4fe3d2510e454b

This is not needed ;)

quoted

Signed-off-by: Derek Basehore <redacted>
---
 drivers/input/touchscreen/elants_i2c.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index d21ca39b0fdb..18ce04ba0173 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c

@@ -284,12 +284,6 @@ static int elants_i2c_sw_reset(struct i2c_client *client)
 		return error;
 	}
 
-	/*
-	 * We should wait at least 10 msec (but no more than 40) before
-	 * sending fastboot or IAP command to the device.
-	 */
-	msleep(30);
-
 	return 0;
 }
 

@@ -500,6 +494,12 @@ static int elants_i2c_fastboot(struct i2c_client *client)
 	const u8 boot_cmd[] = { 0x4D, 0x61, 0x69, 0x6E };
 	int error;
 
+	/*
+	 * We should wait at least 10 msec (but no more than 40) before sending
+	 * fastboot command to the device.
+	 */
+	usleep_range(10 * 1000, 11 * 1000);
+
 	error = elants_i2c_send(client, boot_cmd, sizeof(boot_cmd));
 	if (error) {
 		dev_err(&client->dev, "boot failed: %d\n", error);

@@ -643,6 +643,10 @@ static int elants_i2c_do_update_firmware(struct i2c_client *client,
 			dev_err(&client->dev, "Failed close idle: %d\n", error);
 		msleep(60);
 		elants_i2c_sw_reset(client);
+		/*
+		 * We should wait at least 10 msec (but no more than 40) before
+		 * sending IAP command to the device.
+		 */
 		msleep(20);

So the original comment was talking about timing on fastboot or IAP
command, but the original code had 50 msec wait here (30 from
elants_i2c_sw_reset plus the 20), thus already violating 40 msec rule
for IAP. Unless Elan folks can confirm it is OK to reduce the wait here
I'd prefer we kept it at 50. Firmware update is does not happen that
often anyway.

Thanks.

-- 
Dmitry

-- 
Dmitry

For real now...

On Thu, Aug 23, 2018 at 04:32:11PM -0700, Dmitry Torokhov wrote:

Let's add Elan folks to the discussion.

On Thu, Aug 23, 2018 at 04:30:28PM -0700, Dmitry Torokhov wrote:

quoted

Hi Derek,

On Thu, Aug 23, 2018 at 04:10:13PM -0700, Derek Basehore wrote:

quoted

We only need to wait 10ms instead of 30ms before starting fastboot or
sending IAP on the touchscreen. Also, instead of delaying everytime
sw_reset is called, this delays 10ms in the function that starts
fastboot. There's also an explicit 20ms delay before sending IAP when
updating the firmware, so no additional delay is needed there. This
change also has the benefit of not delaying when wakeup is enabled
during suspend. This is because sw_reset is called, yet fastboot
isn't.

Change-Id: I9e3019720186ba0023891fafeb4fe3d2510e454b

This is not needed ;)

quoted

Signed-off-by: Derek Basehore <redacted>
---
 drivers/input/touchscreen/elants_i2c.c | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/drivers/input/touchscreen/elants_i2c.c b/drivers/input/touchscreen/elants_i2c.c
index d21ca39b0fdb..18ce04ba0173 100644
--- a/drivers/input/touchscreen/elants_i2c.c
+++ b/drivers/input/touchscreen/elants_i2c.c

@@ -284,12 +284,6 @@ static int elants_i2c_sw_reset(struct i2c_client *client)
 		return error;
 	}
 
-	/*
-	 * We should wait at least 10 msec (but no more than 40) before
-	 * sending fastboot or IAP command to the device.
-	 */
-	msleep(30);
-
 	return 0;
 }
 

@@ -500,6 +494,12 @@ static int elants_i2c_fastboot(struct i2c_client *client)
 	const u8 boot_cmd[] = { 0x4D, 0x61, 0x69, 0x6E };
 	int error;
 
+	/*
+	 * We should wait at least 10 msec (but no more than 40) before sending
+	 * fastboot command to the device.
+	 */
+	usleep_range(10 * 1000, 11 * 1000);
+
 	error = elants_i2c_send(client, boot_cmd, sizeof(boot_cmd));
 	if (error) {
 		dev_err(&client->dev, "boot failed: %d\n", error);

@@ -643,6 +643,10 @@ static int elants_i2c_do_update_firmware(struct i2c_client *client,
 			dev_err(&client->dev, "Failed close idle: %d\n", error);
 		msleep(60);
 		elants_i2c_sw_reset(client);
+		/*
+		 * We should wait at least 10 msec (but no more than 40) before
+		 * sending IAP command to the device.
+		 */
 		msleep(20);

So the original comment was talking about timing on fastboot or IAP
command, but the original code had 50 msec wait here (30 from
elants_i2c_sw_reset plus the 20), thus already violating 40 msec rule
for IAP. Unless Elan folks can confirm it is OK to reduce the wait here
I'd prefer we kept it at 50. Firmware update is does not happen that
often anyway.

Thanks.

-- 
Dmitry

-- 
Dmitry

-- 
Dmitry

Hi Derek,

quoted

quoted

On Thu, Aug 23, 2018 at 04:10:13PM -0700, Derek Basehore wrote:

quoted

We only need to wait 10ms instead of 30ms before starting fastboot or
sending IAP on the touchscreen. Also, instead of delaying everytime
sw_reset is called, this delays 10ms in the function that starts
fastboot. There's also an explicit 20ms delay before sending IAP when
updating the firmware, so no additional delay is needed there. This
change also has the benefit of not delaying when wakeup is enabled
during suspend. This is because sw_reset is called, yet fastboot
isn't.

...

quoted

quoted

quoted

-	/*
-	 * We should wait at least 10 msec (but no more than 40) before
-	 * sending fastboot or IAP command to the device.
-	 */
-	msleep(30);
-

moving from 30 to 0 is a bit alarming... what does the datasheet
say?

Sometimes delays are implicit in the system where you are testing
the driver, so that without any msleep it might work in your
system but it might not on others.

+             /*
+              * We should wait at least 10 msec (but no more than 40) before
+              * sending IAP command to the device.
+              */
              msleep(20);

I agree though that it's not nice to wait twice here (even though
as Dmitry says it doesn't hurt so much). Wouldn't it make more
sense to remove this msleep instead?
This way...

+     /*
+      * We should wait at least 10 msec (but no more than 40) before sending
+      * fastboot command to the device.
+      */
+     usleep_range(10 * 1000, 11 * 1000);
+
      error = elants_i2c_send(client, boot_cmd, sizeof(boot_cmd));

... you do not need to add an extra sleep here.

Andi