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media: cec: tegra_cec: keep track of number of Rx Low Drives

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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 <hverkuil+cisco@kernel.org>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
This commit is contained in:
Hans Verkuil 2026-07-10 11:53:18 +02:00 committed by Mauro Carvalho Chehab
parent be627f257c
commit bce7236c16
1 changed files with 19 additions and 0 deletions
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19
drivers/media/cec/platform/tegra/tegra_cec.c
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@ -24,6 +24,7 @@
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/seq_file.h>
#include <linux/clk/tegra.h>
#include <media/cec-notifier.h>
@ -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)