[PATCH 0/3 net-next] net: qca_spi: Improve sync handling

[PATCH 0/3 net-next] net: qca_spi: Improve sync handling

[Stefan Wahren]

This small patch series contains some improvements of the sync
handling. This was discovered while the QCA7000 was doing SLAC
(Signal Level Attenuation Characterization).

Stefan Wahren (3):
  net: qca_spi: Avoid reading signature three times in a row
  net: qca_spi: Avoid re-sync for single signature error
  net: qca_spi: Introduce stat about bad signature

 drivers/net/ethernet/qualcomm/qca_debug.c |  1 +
 drivers/net/ethernet/qualcomm/qca_spi.c   | 10 +++++++++-
 drivers/net/ethernet/qualcomm/qca_spi.h   |  1 +
 3 files changed, 11 insertions(+), 1 deletion(-)

-- 
2.7.4

[PATCH 1/3 net-next] net: qca_spi: Avoid reading signature three times in a row

[Stefan Wahren]

There is no need to read the signature three times. So bail out
in case the second check failed.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/net/ethernet/qualcomm/qca_spi.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/qualcomm/qca_spi.c b/drivers/net/ethernet/qualcomm/qca_spi.c
index ab9b025..3e2a54c 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.c
+++ b/drivers/net/ethernet/qualcomm/qca_spi.c
@@ -506,6 +506,7 @@ qcaspi_qca7k_sync(struct qcaspi *qca, int event)
 		if (signature != QCASPI_GOOD_SIGNATURE) {
 			qca->sync = QCASPI_SYNC_UNKNOWN;
 			netdev_dbg(qca->net_dev, "sync: got CPU on, but signature was invalid, restart\n");
+			return;
 		} else {
 			/* ensure that the WRBUF is empty */
 			qcaspi_read_register(qca, SPI_REG_WRBUF_SPC_AVA,
-- 
2.7.4

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

[Stefan Wahren]

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@i2se.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

[PATCH 3/3 net-next] net: qca_spi: Introduce stat about bad signature

[Stefan Wahren]

In order to identify significant signature issues add a new stat counter,
which increases on bad signature values that causes a sync loss.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
---
 drivers/net/ethernet/qualcomm/qca_debug.c | 1 +
 drivers/net/ethernet/qualcomm/qca_spi.c   | 4 ++++
 drivers/net/ethernet/qualcomm/qca_spi.h   | 1 +
 3 files changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/qualcomm/qca_debug.c b/drivers/net/ethernet/qualcomm/qca_debug.c
index 702aa21..d59fff2 100644
--- a/drivers/net/ethernet/qualcomm/qca_debug.c
+++ b/drivers/net/ethernet/qualcomm/qca_debug.c
@@ -62,6 +62,7 @@ static const char qcaspi_gstrings_stats[][ETH_GSTRING_LEN] = {
 	"SPI errors",
 	"Write verify errors",
 	"Buffer available errors",
+	"Bad signature",
 };
 
 #ifdef CONFIG_DEBUG_FS
diff --git a/drivers/net/ethernet/qualcomm/qca_spi.c b/drivers/net/ethernet/qualcomm/qca_spi.c
index 0937ceb..79fe3ec 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.c
+++ b/drivers/net/ethernet/qualcomm/qca_spi.c
@@ -504,6 +504,9 @@ qcaspi_qca7k_sync(struct qcaspi *qca, int event)
 		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
 		qcaspi_read_register(qca, SPI_REG_SIGNATURE, &signature);
 		if (signature != QCASPI_GOOD_SIGNATURE) {
+			if (qca->sync == QCASPI_SYNC_READY)
+				qca->stats.bad_signature++;
+
 			qca->sync = QCASPI_SYNC_UNKNOWN;
 			netdev_dbg(qca->net_dev, "sync: got CPU on, but signature was invalid, restart\n");
 			return;
@@ -531,6 +534,7 @@ qcaspi_qca7k_sync(struct qcaspi *qca, int event)
 
 		if (signature != QCASPI_GOOD_SIGNATURE) {
 			qca->sync = QCASPI_SYNC_UNKNOWN;
+			qca->stats.bad_signature++;
 			netdev_dbg(qca->net_dev, "sync: bad signature, restart\n");
 			/* don't reset right away */
 			return;
diff --git a/drivers/net/ethernet/qualcomm/qca_spi.h b/drivers/net/ethernet/qualcomm/qca_spi.h
index d13a67e..3067356 100644
--- a/drivers/net/ethernet/qualcomm/qca_spi.h
+++ b/drivers/net/ethernet/qualcomm/qca_spi.h
@@ -75,6 +75,7 @@ struct qcaspi_stats {
 	u64 spi_err;
 	u64 write_verify_failed;
 	u64 buf_avail_err;
+	u64 bad_signature;
 };
 
 struct qcaspi {
-- 
2.7.4

Re: [PATCH 0/3 net-next] net: qca_spi: Improve sync handling

[patchwork-bot+netdevbpf]

Hello:

This series was applied to netdev/net-next.git (refs/heads/master):

On Sat,  8 May 2021 14:36:32 +0200 you wrote:
> This small patch series contains some improvements of the sync
> handling. This was discovered while the QCA7000 was doing SLAC
> (Signal Level Attenuation Characterization).
> 
> Stefan Wahren (3):
>   net: qca_spi: Avoid reading signature three times in a row
>   net: qca_spi: Avoid re-sync for single signature error
>   net: qca_spi: Introduce stat about bad signature
> 
> [...]

Here is the summary with links:
  - [1/3,net-next] net: qca_spi: Avoid reading signature three times in a row
    https://git.kernel.org/netdev/net-next/c/b76078df1593
  - [2/3,net-next] net: qca_spi: Avoid re-sync for single signature error
    https://git.kernel.org/netdev/net-next/c/6e03f3ff29c1
  - [3/3,net-next] net: qca_spi: Introduce stat about bad signature
    https://git.kernel.org/netdev/net-next/c/a53935674563

You are awesome, thank you!
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