Count how many Low Drive, Error and Arbitration Lost transmit
status errors occurred, and expose that in debugfs.
Also log the first 8 transmits that result in Low Drive or Error
conditions. That really should not happen with well-behaved CEC devices
and good HDMI cables.
This is useful to detect and debug HDMI cable issues.
Signed-off-by: Hans Verkuil <hverkuil-cisco@xxxxxxxxx>
---
Changes since v4:
- Improve kerneldoc description of the new fields
Changes since v3:
- Document new fields in kerneldoc
Changes since v2:
- Fix spaces instead of TAB issue in two lines.
Changes since v1:
- Log the first 8 transmits that resulted in a Low Drive or Error status.
---
drivers/media/cec/core/cec-adap.c | 54 ++++++++++++++++++++++++++++---
include/media/cec.h | 22 +++++++++++--
2 files changed, 69 insertions(+), 7 deletions(-)
diff --git a/drivers/media/cec/core/cec-adap.c b/drivers/media/cec/core/cec-adap.c
index 09ca83c23329..b9a2753e0846 100644
--- a/drivers/media/cec/core/cec-adap.c
+++ b/drivers/media/cec/core/cec-adap.c
@@ -511,7 +511,7 @@ int cec_thread_func(void *_adap)
pr_warn("cec-%s: transmit timed out\n", adap->name);
}
adap->transmit_in_progress = false;
- adap->tx_timeouts++;
+ adap->tx_timeout_cnt++;
goto unlock;
}
@@ -625,6 +625,33 @@ void cec_transmit_done_ts(struct cec_adapter *adap, u8 status,
msg->tx_low_drive_cnt += low_drive_cnt;
msg->tx_error_cnt += error_cnt;
+ adap->tx_arb_lost_cnt += arb_lost_cnt;
+ adap->tx_low_drive_cnt += low_drive_cnt;
+ adap->tx_error_cnt += error_cnt;
+
+ /*
+ * Low Drive transmission errors should really not happen for
+ * well-behaved CEC devices and proper HDMI cables.
+ *
+ * Ditto for the 'Error' status.
+ *
+ * For the first few times that this happens, log this.
+ * Stop logging after that, since that will not add any more
+ * useful information and instead it will just flood the kernel log.
+ */
+ if (done && adap->tx_low_drive_log_cnt < 8 && msg->tx_low_drive_cnt) {
+ adap->tx_low_drive_log_cnt++;
+ dprintk(0, "low drive counter: %u (seq %u: %*ph)\n",
+ msg->tx_low_drive_cnt, msg->sequence,
+ msg->len, msg->msg);
+ }
+ if (done && adap->tx_error_log_cnt < 8 && msg->tx_error_cnt) {
+ adap->tx_error_log_cnt++;
+ dprintk(0, "error counter: %u (seq %u: %*ph)\n",
+ msg->tx_error_cnt, msg->sequence,
+ msg->len, msg->msg);
+ }
+
/* Mark that we're done with this transmit */
adap->transmitting = NULL;
@@ -1607,6 +1634,8 @@ int cec_adap_enable(struct cec_adapter *adap)
if (enable) {
adap->last_initiator = 0xff;
adap->transmit_in_progress = false;
+ adap->tx_low_drive_log_cnt = 0;
+ adap->tx_error_log_cnt = 0;
ret = adap->ops->adap_enable(adap, true);
if (!ret) {
/*
@@ -2260,10 +2289,25 @@ int cec_adap_status(struct seq_file *file, void *priv)
if (adap->monitor_pin_cnt)
seq_printf(file, "file handles in Monitor Pin mode: %u\n",
adap->monitor_pin_cnt);
- if (adap->tx_timeouts) {
- seq_printf(file, "transmit timeouts: %u\n",
- adap->tx_timeouts);
- adap->tx_timeouts = 0;
+ if (adap->tx_timeout_cnt) {
+ seq_printf(file, "transmit timeout count: %u\n",
+ adap->tx_timeout_cnt);
+ adap->tx_timeout_cnt = 0;
+ }
+ if (adap->tx_low_drive_cnt) {
+ seq_printf(file, "transmit low drive count: %u\n",
+ adap->tx_low_drive_cnt);
+ adap->tx_low_drive_cnt = 0;
+ }
+ if (adap->tx_arb_lost_cnt) {
+ seq_printf(file, "transmit arbitration lost count: %u\n",
+ adap->tx_arb_lost_cnt);
+ adap->tx_arb_lost_cnt = 0;
+ }
+ if (adap->tx_error_cnt) {
+ seq_printf(file, "transmit error count: %u\n",
+ adap->tx_error_cnt);
+ adap->tx_error_cnt = 0;
}
data = adap->transmitting;
if (data)
diff --git a/include/media/cec.h b/include/media/cec.h
index 53e4b2eb2b26..d77982685116 100644
--- a/include/media/cec.h
+++ b/include/media/cec.h
@@ -207,7 +207,20 @@ struct cec_adap_ops {
* passthrough mode.
* @log_addrs: current logical addresses
* @conn_info: current connector info
- * @tx_timeouts: number of transmit timeouts
+ * @tx_timeout_cnt: count the number of Timed Out transmits.
+ * Reset to 0 when this is reported in cec_adap_status().
+ * @tx_low_drive_cnt: count the number of Low Drive transmits.
+ * Reset to 0 when this is reported in cec_adap_status().
+ * @tx_error_cnt: count the number of Error transmits.
+ * Reset to 0 when this is reported in cec_adap_status().
+ * @tx_arb_lost_cnt: count the number of Arb Lost transmits.
+ * Reset to 0 when this is reported in cec_adap_status().
+ * @tx_low_drive_log_cnt: number of logged Low Drive transmits since the
+ * adapter was enabled. Used to avoid flooding the kernel
+ * log if this happens a lot.
+ * @tx_error_log_cnt: number of logged Error transmits since the adapter was
+ * enabled. Used to avoid flooding the kernel log if this
+ * happens a lot.
* @notifier: CEC notifier
* @pin: CEC pin status struct
* @cec_dir: debugfs cec directory
@@ -262,7 +275,12 @@ struct cec_adapter {
struct cec_log_addrs log_addrs;
struct cec_connector_info conn_info;
- u32 tx_timeouts;
+ u32 tx_timeout_cnt;
+ u32 tx_low_drive_cnt;
+ u32 tx_error_cnt;
+ u32 tx_arb_lost_cnt;
+ u32 tx_low_drive_log_cnt;
+ u32 tx_error_log_cnt;
#ifdef CONFIG_CEC_NOTIFIER
struct cec_notifier *notifier;
--
2.42.0
