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Useful for detecting > potential hardware/cable problems as it suggests unstable or > incorrect voltage levels. >=20 > Note that the Tx Low Drive conditions are already logged in > the CEC core. >=20 > Signed-off-by: Hans Verkuil > --- > drivers/media/cec/platform/tegra/tegra_cec.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) >=20 > 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 > =20 > #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; > }; > =20 > static inline u32 cec_read(struct tegra_cec *cec, u32 reg) > @@ -116,6 +118,13 @@ static irqreturn_t tegra_cec_irq_handler(int irq, vo= id *data) > return IRQ_WAKE_THREAD; > } > =20 > + 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); > =20 > /* > @@ -318,11 +328,20 @@ static int tegra_cec_adap_transmit(struct cec_adapt= er *adap, u8 attempts, > return 0; > } > =20 > +static void tegra_cec_adap_status(struct cec_adapter *adap, struct seq_f= ile *file) > +{ > + struct tegra_cec *cec =3D 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 =3D { > .adap_enable =3D tegra_cec_adap_enable, > .adap_log_addr =3D tegra_cec_adap_log_addr, > .adap_transmit =3D tegra_cec_adap_transmit, > .adap_monitor_all_enable =3D tegra_cec_adap_monitor_all_enable, > + .adap_status =3D tegra_cec_adap_status, > }; > =20 > static int tegra_cec_probe(struct platform_device *pdev) > --=20 > 2.53.0 >=20 >=20 Reviewed-by: Mikko Perttunen