[RFC PATCH 0/2] i2c: check correct size of maximum RECV_LEN packet

[RFC PATCH 0/2] i2c: check correct size of maximum RECV_LEN packet

[Wolfram Sang]

I am preparing to add RECV_LEN support to Renesas I2C drivers. On my
way, I found these two peculiarities. Let's discuss them.

Wolfram Sang (2):
  i2c: mlxcpld: check correct size of maximum RECV_LEN packet
  i2c: octeon: check correct size of maximum RECV_LEN packet

 drivers/i2c/busses/i2c-mlxcpld.c     | 4 ++--
 drivers/i2c/busses/i2c-octeon-core.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

-- 
2.20.1

[RFC PATCH 1/2] i2c: mlxcpld: check correct size of maximum RECV_LEN packet

[Wolfram Sang]

I2C_SMBUS_BLOCK_MAX defines already the maximum number as defined in the
SMBus 2.0 specs. I don't see a reason to add 1 here. Also, fix the errno
to what is suggested for this error.

Fixes: c9bfdc7c16cb ("i2c: mlxcpld: Add support for smbus block read transaction")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Only build tested, I don't have the HW. Please let me know if I
overlooked something, but to the best of my knowledge, this +1 is wrong.

 drivers/i2c/busses/i2c-mlxcpld.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mlxcpld.c b/drivers/i2c/busses/i2c-mlxcpld.c
index 2fd717d8dd30..71d7bae2cbca 100644
--- a/drivers/i2c/busses/i2c-mlxcpld.c
+++ b/drivers/i2c/busses/i2c-mlxcpld.c
@@ -337,9 +337,9 @@ static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv *priv)
 		if (priv->smbus_block && (val & MLXCPLD_I2C_SMBUS_BLK_BIT)) {
 			mlxcpld_i2c_read_comm(priv, MLXCPLD_LPCI2C_NUM_DAT_REG,
 					      &datalen, 1);
-			if (unlikely(datalen > (I2C_SMBUS_BLOCK_MAX + 1))) {
+			if (unlikely(datalen > I2C_SMBUS_BLOCK_MAX)) {
 				dev_err(priv->dev, "Incorrect smbus block read message len\n");
-				return -E2BIG;
+				return -EPROTO;
 			}
 		} else {
 			datalen = priv->xfer.data_len;
-- 
2.20.1

RE: [RFC PATCH 1/2] i2c: mlxcpld: check correct size of maximum RECV_LEN packet

[Michael Shych]

Hi Wolfram,

You are right, +1 isn't required.
Checked your patch also on HW. It works OK.

Thank you,
    Michael.

> -----Original Message-----
> From: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Sent: Sunday, June 28, 2020 2:53 PM
> To: linux-i2c@vger.kernel.org
> Cc: linux-renesas-soc@vger.kernel.org; Wolfram Sang <wsa+renesas@sang-
> engineering.com>; Vadim Pasternak <vadimp@mellanox.com>; Michael Shych
> <michaelsh@mellanox.com>; Wolfram Sang <wsa@kernel.org>; linux-
> kernel@vger.kernel.org
> Subject: [RFC PATCH 1/2] i2c: mlxcpld: check correct size of maximum RECV_LEN
> packet
> 
> I2C_SMBUS_BLOCK_MAX defines already the maximum number as defined in
> the
> SMBus 2.0 specs. I don't see a reason to add 1 here. Also, fix the errno
> to what is suggested for this error.
> 
> Fixes: c9bfdc7c16cb ("i2c: mlxcpld: Add support for smbus block read
> transaction")
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> 
> Only build tested, I don't have the HW. Please let me know if I
> overlooked something, but to the best of my knowledge, this +1 is wrong.
> 
>  drivers/i2c/busses/i2c-mlxcpld.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-mlxcpld.c b/drivers/i2c/busses/i2c-mlxcpld.c
> index 2fd717d8dd30..71d7bae2cbca 100644
> --- a/drivers/i2c/busses/i2c-mlxcpld.c
> +++ b/drivers/i2c/busses/i2c-mlxcpld.c
> @@ -337,9 +337,9 @@ static int mlxcpld_i2c_wait_for_tc(struct mlxcpld_i2c_priv
> *priv)
>  		if (priv->smbus_block && (val &
> MLXCPLD_I2C_SMBUS_BLK_BIT)) {
>  			mlxcpld_i2c_read_comm(priv,
> MLXCPLD_LPCI2C_NUM_DAT_REG,
>  					      &datalen, 1);
> -			if (unlikely(datalen > (I2C_SMBUS_BLOCK_MAX + 1))) {
> +			if (unlikely(datalen > I2C_SMBUS_BLOCK_MAX)) {
>  				dev_err(priv->dev, "Incorrect smbus block read
> message len\n");
> -				return -E2BIG;
> +				return -EPROTO;
>  			}
>  		} else {
>  			datalen = priv->xfer.data_len;
> --
> 2.20.1

[RFC PATCH 2/2] i2c: octeon: check correct size of maximum RECV_LEN packet

[Wolfram Sang]

I2C_SMBUS_BLOCK_MAX defines already the maximum number as defined in the
SMBus 2.0 specs. I don't see a reason to add 1 here.

Fixes: 886f6f8337dd ("i2c: octeon: Support I2C_M_RECV_LEN")
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Only build tested, I don't have the HW. Please let me know if I
overlooked something, but to the best of my knowledge, this +1 is wrong.

 drivers/i2c/busses/i2c-octeon-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
index d9607905dc2f..845eda70b8ca 100644
--- a/drivers/i2c/busses/i2c-octeon-core.c
+++ b/drivers/i2c/busses/i2c-octeon-core.c
@@ -347,7 +347,7 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
 		if (result)
 			return result;
 		if (recv_len && i == 0) {
-			if (data[i] > I2C_SMBUS_BLOCK_MAX + 1)
+			if (data[i] > I2C_SMBUS_BLOCK_MAX)
 				return -EPROTO;
 			length += data[i];
 		}
-- 
2.20.1

Re: [RFC PATCH 2/2] i2c: octeon: check correct size of maximum RECV_LEN packet

[Wolfram Sang]

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On Sun, Jun 28, 2020 at 01:52:45PM +0200, Wolfram Sang wrote:
> I2C_SMBUS_BLOCK_MAX defines already the maximum number as defined in the
> SMBus 2.0 specs. I don't see a reason to add 1 here.
> 
> Fixes: 886f6f8337dd ("i2c: octeon: Support I2C_M_RECV_LEN")
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---

Robert, is this correct?

> 
> Only build tested, I don't have the HW. Please let me know if I
> overlooked something, but to the best of my knowledge, this +1 is wrong.
> 
>  drivers/i2c/busses/i2c-octeon-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-octeon-core.c b/drivers/i2c/busses/i2c-octeon-core.c
> index d9607905dc2f..845eda70b8ca 100644
> --- a/drivers/i2c/busses/i2c-octeon-core.c
> +++ b/drivers/i2c/busses/i2c-octeon-core.c
> @@ -347,7 +347,7 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
>  		if (result)
>  			return result;
>  		if (recv_len && i == 0) {
> -			if (data[i] > I2C_SMBUS_BLOCK_MAX + 1)
> +			if (data[i] > I2C_SMBUS_BLOCK_MAX)
>  				return -EPROTO;
>  			length += data[i];
>  		}
> -- 
> 2.20.1
> 

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