[PATCH v2 1/2] NFC: nxp-nci: Don't issue a zero length i2c_master_read()

[PATCH v2 1/2] NFC: nxp-nci: Don't issue a zero length i2c_master_read()

[Michael Walle]

There are packets which doesn't have a payload. In that case, the second
i2c_master_read() will have a zero length. But because the NFC
controller doesn't have any data left, it will NACK the I2C read and
-ENXIO will be returned. In case there is no payload, just skip the
second i2c master read.

Fixes: 6be88670fc59 ("NFC: nxp-nci_i2c: Add I2C support to NXP NCI driver")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
---
changes since v1:
 - none

 drivers/nfc/nxp-nci/i2c.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/nfc/nxp-nci/i2c.c b/drivers/nfc/nxp-nci/i2c.c
index 7e451c10985d..e8f3b35afbee 100644
--- a/drivers/nfc/nxp-nci/i2c.c
+++ b/drivers/nfc/nxp-nci/i2c.c
@@ -162,6 +162,9 @@ static int nxp_nci_i2c_nci_read(struct nxp_nci_i2c_phy *phy,
 
 	skb_put_data(*skb, (void *)&header, NCI_CTRL_HDR_SIZE);
 
+	if (!header.plen)
+		return 0;
+
 	r = i2c_master_recv(client, skb_put(*skb, header.plen), header.plen);
 	if (r != header.plen) {
 		nfc_err(&client->dev,
-- 
2.30.2

[PATCH v2 2/2] NFC: nxp-nci: don't print header length mismatch on i2c error

[Michael Walle]

Don't print a misleading header length mismatch error if the i2c call
returns an error. Instead just return the error code without any error
message.

Signed-off-by: Michael Walle <michael@walle.cc>
---
changes since v1:
 - reworded commit message
 - removed fixes tag
 - removed nfc_err() call, as it is done elsewhere in this driver
 - nxp_nci_i2c_fw_read() has the same issue. also handle it there

 drivers/nfc/nxp-nci/i2c.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/nfc/nxp-nci/i2c.c b/drivers/nfc/nxp-nci/i2c.c
index e8f3b35afbee..ae2ba08d8ac3 100644
--- a/drivers/nfc/nxp-nci/i2c.c
+++ b/drivers/nfc/nxp-nci/i2c.c
@@ -122,7 +122,9 @@ static int nxp_nci_i2c_fw_read(struct nxp_nci_i2c_phy *phy,
 	skb_put_data(*skb, &header, NXP_NCI_FW_HDR_LEN);
 
 	r = i2c_master_recv(client, skb_put(*skb, frame_len), frame_len);
-	if (r != frame_len) {
+	if (r < 0) {
+		goto fw_read_exit_free_skb;
+	} else if (r != frame_len) {
 		nfc_err(&client->dev,
 			"Invalid frame length: %u (expected %zu)\n",
 			r, frame_len);
@@ -166,7 +168,9 @@ static int nxp_nci_i2c_nci_read(struct nxp_nci_i2c_phy *phy,
 		return 0;
 
 	r = i2c_master_recv(client, skb_put(*skb, header.plen), header.plen);
-	if (r != header.plen) {
+	if (r < 0) {
+		goto nci_read_exit_free_skb;
+	} else if (r != header.plen) {
 		nfc_err(&client->dev,
 			"Invalid frame payload length: %u (expected %u)\n",
 			r, header.plen);
-- 
2.30.2

Re: [PATCH v2 2/2] NFC: nxp-nci: don't print header length mismatch on i2c error

[Krzysztof Kozlowski]

On 27/06/2022 19:06, Michael Walle wrote:
> Don't print a misleading header length mismatch error if the i2c call
> returns an error. Instead just return the error code without any error
> message.
> 
> Signed-off-by: Michael Walle <michael@walle.cc>
> ---
> changes since v1:
>  - reworded commit message
>  - removed fixes tag
>  - removed nfc_err() call, as it is done elsewhere in this driver
>  - nxp_nci_i2c_fw_read() has the same issue. also handle it there
> 


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


Best regards,
Krzysztof

Re: [PATCH v2 1/2] NFC: nxp-nci: Don't issue a zero length i2c_master_read()

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net.git (master)
by David S. Miller <davem@davemloft.net>:

On Mon, 27 Jun 2022 19:06:42 +0200 you wrote:
> There are packets which doesn't have a payload. In that case, the second
> i2c_master_read() will have a zero length. But because the NFC
> controller doesn't have any data left, it will NACK the I2C read and
> -ENXIO will be returned. In case there is no payload, just skip the
> second i2c master read.
> 
> Fixes: 6be88670fc59 ("NFC: nxp-nci_i2c: Add I2C support to NXP NCI driver")
> Signed-off-by: Michael Walle <michael@walle.cc>
> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> 
> [...]

Here is the summary with links:
  - [v2,1/2] NFC: nxp-nci: Don't issue a zero length i2c_master_read()
    https://git.kernel.org/netdev/net/c/eddd95b94239
  - [v2,2/2] NFC: nxp-nci: don't print header length mismatch on i2c error
    https://git.kernel.org/netdev/net/c/9577fc5fdc8b

You are awesome, thank you!
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