[PATCH] i2c: i801: Fix a refactoring that broke a touchpad on Lenovo P1

[PATCH] i2c: i801: Fix a refactoring that broke a touchpad on Lenovo P1

[Maxim Levitsky]

Commit 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")
introduced a slight functional change: the status variable is now
overwritten with the length of an SMBUS tranasaction,
even in case of success.

This breaks the touchpad on at least my Lenovo P1:

rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
rmi4_physical rmi4-00: RMI initial reset failed! Continuing in spite of this.
rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
rmi4_physical rmi4-00: IRQ counting failed with code -6.

Fixes: 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")

Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
 drivers/i2c/busses/i2c-i801.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
index a6861660cb8c..79870dd7a014 100644
--- a/drivers/i2c/busses/i2c-i801.c
+++ b/drivers/i2c/busses/i2c-i801.c
@@ -536,11 +536,12 @@ static int i801_block_transaction_by_block(struct i801_priv *priv,
 
 	if (read_write == I2C_SMBUS_READ ||
 	    command == I2C_SMBUS_BLOCK_PROC_CALL) {
-		status = i801_get_block_len(priv);
-		if (status < 0)
+		len = i801_get_block_len(priv);
+		if (len < 0) {
+			status = len;
 			goto out;
+		}
 
-		len = status;
 		data->block[0] = len;
 		inb_p(SMBHSTCNT(priv));	/* reset the data buffer index */
 		for (i = 0; i < len; i++)
-- 
2.40.1

Re: [PATCH] i2c: i801: Fix a refactoring that broke a touchpad on Lenovo P1

[Heiner Kallweit]

On 21.03.2024 15:19, Maxim Levitsky wrote:
> Commit 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")
> introduced a slight functional change: the status variable is now
> overwritten with the length of an SMBUS tranasaction,
> even in case of success.
> 
> This breaks the touchpad on at least my Lenovo P1:
> 
> rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
> rmi4_physical rmi4-00: RMI initial reset failed! Continuing in spite of this.
> rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
> rmi4_physical rmi4-00: IRQ counting failed with code -6.
> 
> Fixes: 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")
> 
> Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  drivers/i2c/busses/i2c-i801.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index a6861660cb8c..79870dd7a014 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -536,11 +536,12 @@ static int i801_block_transaction_by_block(struct i801_priv *priv,
>  
>  	if (read_write == I2C_SMBUS_READ ||
>  	    command == I2C_SMBUS_BLOCK_PROC_CALL) {
> -		status = i801_get_block_len(priv);
> -		if (status < 0)
> +		len = i801_get_block_len(priv);
> +		if (len < 0) {
> +			status = len;
>  			goto out;
> +		}
>  
> -		len = status;
>  		data->block[0] = len;
>  		inb_p(SMBHSTCNT(priv));	/* reset the data buffer index */
>  		for (i = 0; i < len; i++)

Indeed, my bad.

Reviewed-by: Heiner Kallweit <hkallweit1@gmail.com>

Re: [PATCH] i2c: i801: Fix a refactoring that broke a touchpad on Lenovo P1

[Andi Shyti]

Hi Maxim,

On Thu, Mar 21, 2024 at 10:19:19AM -0400, Maxim Levitsky wrote:
> Commit 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")
> introduced a slight functional change: the status variable is now
> overwritten with the length of an SMBUS tranasaction,
> even in case of success.
> 
> This breaks the touchpad on at least my Lenovo P1:
> 
> rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
> rmi4_physical rmi4-00: RMI initial reset failed! Continuing in spite of this.
> rmi4_physical rmi4-00: Read PDT entry at 0x00e9 failed, code: -6.
> rmi4_physical rmi4-00: IRQ counting failed with code -6.
> 
> Fixes: 857cc04cdf50 ("i2c: i801: Add helper i801_get_block_len")
> 

next time please drop this blank line here.

Applied to i2c/i2c-host-fixes on

git://git.kernel.org/pub/scm/linux/kernel/git/andi.shyti/linux.git

Thank you,
Andi

Patches applied
===============
[1/1] i2c: i801: Fix a refactoring that broke a touchpad on Lenovo P1
      commit: a5894bc48f64caa86dbea1744d067c925303c5fc