From bce7236c16c2c6fb99857d90b928db135acf68bb Mon Sep 17 00:00:00 2001 From: Hans Verkuil Date: Fri, 10 Jul 2026 11:53:18 +0200 Subject: [PATCH] media: cec: tegra_cec: keep track of number of Rx Low Drives Keep track of Rx Low Drive conditions. Useful for detecting potential hardware/cable problems as it suggests unstable or incorrect voltage levels. Note that the Tx Low Drive conditions are already logged in the CEC core. Signed-off-by: Hans Verkuil Reviewed-by: Mikko Perttunen Signed-off-by: Mauro Carvalho Chehab --- drivers/media/cec/platform/tegra/tegra_cec.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/drivers/media/cec/platform/tegra/tegra_cec.c b/drivers/media/cec/platform/tegra/tegra_cec.c index f8ffaeb78118..e22a4625f192 100644 --- a/drivers/media/cec/platform/tegra/tegra_cec.c +++ b/drivers/media/cec/platform/tegra/tegra_cec.c @@ -24,6 +24,7 @@ #include #include #include +#include #include #include @@ -47,6 +48,7 @@ struct tegra_cec { u32 tx_buf[CEC_MAX_MSG_SIZE]; u8 tx_buf_cur; u8 tx_buf_cnt; + u32 rx_total_low_drives; }; static inline u32 cec_read(struct tegra_cec *cec, u32 reg) @@ -116,6 +118,13 @@ static irqreturn_t tegra_cec_irq_handler(int irq, void *data) return IRQ_WAKE_THREAD; } + if (status & TEGRA_CEC_INT_STAT_RX_BUS_ERROR_DETECTED) { + dev_warn_ratelimited(dev, "RX bus error detected, generated low drive\n"); + cec->rx_total_low_drives++; + cec_write(cec, TEGRA_CEC_INT_STAT, + TEGRA_CEC_INT_STAT_RX_BUS_ERROR_DETECTED); + } + if ((status & TEGRA_CEC_INT_STAT_TX_ARBITRATION_FAILED) || (status & TEGRA_CEC_INT_STAT_TX_BUS_ANOMALY_DETECTED)) { tegra_cec_error_recovery(cec); @@ -241,6 +250,7 @@ static int tegra_cec_adap_enable(struct cec_adapter *adap, bool enable) TEGRA_CEC_INT_MASK_TX_BUS_ANOMALY_DETECTED | TEGRA_CEC_INT_MASK_TX_FRAME_TRANSMITTED | TEGRA_CEC_INT_MASK_RX_REGISTER_FULL | + TEGRA_CEC_INT_MASK_RX_BUS_ERROR_DETECTED | TEGRA_CEC_INT_MASK_RX_START_BIT_DETECTED); /* @@ -318,11 +328,20 @@ static int tegra_cec_adap_transmit(struct cec_adapter *adap, u8 attempts, return 0; } +static void tegra_cec_adap_status(struct cec_adapter *adap, struct seq_file *file) +{ + struct tegra_cec *cec = adap->priv; + + seq_printf(file, "receive low drive count: %u\n", + cec->rx_total_low_drives); +} + static const struct cec_adap_ops tegra_cec_ops = { .adap_enable = tegra_cec_adap_enable, .adap_log_addr = tegra_cec_adap_log_addr, .adap_transmit = tegra_cec_adap_transmit, .adap_monitor_all_enable = tegra_cec_adap_monitor_all_enable, + .adap_status = tegra_cec_adap_status, }; static int tegra_cec_probe(struct platform_device *pdev)