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From:   Michael Walle <michael@walle.cc>
To:     Charles Gorand <charles.gorand@effinnov.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc:     =?UTF-8?q?Cl=C3=A9ment=20Perrochaud?= <clement.perrochaud@nxp.com>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Michael Walle <michael@walle.cc>
Subject: [PATCH 2/2] NFC: nxp-nci: Don't issue a zero length i2c_master_read()
Date:   Sun, 26 Jun 2022 21:42:43 +0200
Message-Id: <20220626194243.4059870-2-michael@walle.cc>
In-Reply-To: <20220626194243.4059870-1-michael@walle.cc>
References: <20220626194243.4059870-1-michael@walle.cc>
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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>
---
 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 9c80d5a6d56b..c9361b5249b7 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 < 0) {
 		nfc_err(&client->dev, "I2C receive error %pe\n", ERR_PTR(r));
-- 
2.30.2