netdev - [PATCH 2/3 net-next] net: qca_spi: Avoid re-sync for single signature error

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Date:   Sat,  8 May 2021 14:36:34 +0200
From:   Stefan Wahren <stefan.wahren@...e.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Stefan Wahren <stefan.wahren@...e.com>
Subject: [PATCH 2/3 net-next] net: qca_spi: Avoid re-sync for single signature error

Setting a new network key would cause a reset of the QCA7000. Usually
the driver only notice the SPI interrupt and a single signature error.
So avoid the whole re-sync process (possible packet loss, transmit queue
stop and no carrier for at least 1 second) in this case.

Signed-off-by: Stefan Wahren <stefan.wahren@...e.com>
---
 drivers/net/ethernet/qualcomm/qca_spi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/qualcomm/qca_spi.c b/drivers/net/ethernet/qualcomm/qca_spi.c
index 3e2a54c..0937ceb 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.c
+++ b/drivers/net/ethernet/qualcomm/qca_spi.c
@@ -524,8 +524,11 @@ qcaspi_qca7k_sync(struct qcaspi *qca, int event)
 
 	switch (qca->sync) {
 	case QCASPI_SYNC_READY:
-		/* Read signature, if not valid go to unknown state. */
+		/* Check signature twice, if not valid go to unknown state. */
 		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
+		if (signature != QCASPI_GOOD_SIGNATURE)
+			qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
+
 		if (signature != QCASPI_GOOD_SIGNATURE) {
 			qca->sync = QCASPI_SYNC_UNKNOWN;
 			netdev_dbg(qca->net_dev, "sync: bad signature, restart\n");
-- 
2.7.4