RE: [PATCH] Input: elan_i2c - Prevent breaking of FW updating from unexpected signal

[廖崇榮 <kt.liao@emc.com.tw>]

Hi Dmitry

-----Original Message-----
From: Dmitry Torokhov [mailto:dmitry.torokhov@gmail.com] 
Sent: Wednesday, May 24, 2017 5:14 AM
To: KT Liao
Cc: linux-kernel@vger.kernel.org; linux-input@vger.kernel.org;
phoenix@emc.com.tw
Subject: Re: [PATCH] Input: elan_i2c - Prevent breaking of FW updating from
unexpected signal

Hi KT,

On Tue, May 23, 2017 at 10:32:02PM +0800, KT Liao wrote:
> Use wait_for_completion_timeout to prevent breaking of FW updating from
unexpected signal
> 
> Signed-off-by: KT Liao <kt.liao@emc.com.tw>
> ---
>  drivers/input/mouse/elan_i2c_i2c.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/mouse/elan_i2c_i2c.c
b/drivers/input/mouse/elan_i2c_i2c.c
> index 3be75c6e..34356c7 100644
> --- a/drivers/input/mouse/elan_i2c_i2c.c
> +++ b/drivers/input/mouse/elan_i2c_i2c.c
> @@ -619,7 +619,7 @@ static int elan_i2c_finish_fw_update(struct i2c_client
*client,
>  
>  	error = elan_i2c_write_cmd(client, ETP_I2C_STAND_CMD,
ETP_I2C_RESET);
>  	if (!error)
> -		ret = wait_for_completion_interruptible_timeout(completion,
> +		ret = wait_for_completion_timeout(completion,
>
msecs_to_jiffies(300));
>  	disable_irq(client->irq);
>  
> -- 
> 2.7.4
> 

wait_for_completion_timeout(), unlike
wait_for_completion_interruptible_timeout() returns unsigned long, so
the code below checking if 'ret' is negative, is no longer needed. How
about the version of the patch below?
[KT] : Thanks, it's ok. We have tested it on some Chrome system.
-- 
Dmitry


Input: elan_i2c - ignore signals when finishing updating firmware

From: KT Liao <kt.liao@emc.com.tw>

Use wait_for_completion_timeout() instead of
wait_for_completion_interruptible_timeout() to avoid stray signals ruining
firmware update. Our timeout is only 300 msec so we are fine simply letting
it expire in case device misbehaves.

Signed-off-by: KT Liao <kt.liao@emc.com.tw>
Patchwork-Id: 9742857
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/mouse/elan_i2c_i2c.c |   21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/drivers/input/mouse/elan_i2c_i2c.c
b/drivers/input/mouse/elan_i2c_i2c.c
index 3be75c6e8090..278832047075 100644
--- a/drivers/input/mouse/elan_i2c_i2c.c
+++ b/drivers/input/mouse/elan_i2c_i2c.c
@@ -609,7 +609,6 @@ static int elan_i2c_finish_fw_update(struct i2c_client
*client,
 				     struct completion *completion)
 {
 	struct device *dev = &client->dev;
-	long ret;
 	int error;
 	int len;
 	u8 buffer[ETP_I2C_INF_LENGTH];
@@ -618,23 +617,19 @@ static int elan_i2c_finish_fw_update(struct i2c_client
*client,
 	enable_irq(client->irq);
 
 	error = elan_i2c_write_cmd(client, ETP_I2C_STAND_CMD,
ETP_I2C_RESET);
-	if (!error)
-		ret = wait_for_completion_interruptible_timeout(completion,
-							msecs_to_jiffies(300
));
-	disable_irq(client->irq);
-
 	if (error) {
 		dev_err(dev, "device reset failed: %d\n", error);
-		return error;
-	} else if (ret == 0) {
+	} else if (!wait_for_completion_timeout(completion,
+						msecs_to_jiffies(300))) {
 		dev_err(dev, "timeout waiting for device reset\n");
-		return -ETIMEDOUT;
-	} else if (ret < 0) {
-		error = ret;
-		dev_err(dev, "error waiting for device reset: %d\n", error);
-		return error;
+		error = -ETIMEDOUT;
 	}
 
+	disable_irq(client->irq);
+
+	if (error)
+		return error;
+
 	len = i2c_master_recv(client, buffer, ETP_I2C_INF_LENGTH);
 	if (len != ETP_I2C_INF_LENGTH) {
 		error = len < 0 ? len : -EIO;