On Mon Jun 30 13:08:47 2025 +0200, Hans Verkuil wrote:
> If rx-no-low-drive is set, then the CEC pin framework will disable
> the detection of situations where a Low Drive has to be generated.
>
> So if this is set, then we will never generate Low Drives.
>
> This helps testing whether other CEC devices generate Low Drive
> pulses by ensuring it is not us that is generating them.
>
> Signed-off-by: Hans Verkuil <hverk...@xs4all.nl>
> Signed-off-by: Mauro Carvalho Chehab <mchehab+hua...@kernel.org>
Patch committed.
Thanks,
Mauro Carvalho Chehab
drivers/media/cec/core/cec-pin-error-inj.c | 11 +++++++++++
drivers/media/cec/core/cec-pin-priv.h | 1 +
drivers/media/cec/core/cec-pin.c | 2 +-
3 files changed, 13 insertions(+), 1 deletion(-)
---
diff --git a/drivers/media/cec/core/cec-pin-error-inj.c
b/drivers/media/cec/core/cec-pin-error-inj.c
index 68cbd83dfd6e..d9e613c7ce3f 100644
--- a/drivers/media/cec/core/cec-pin-error-inj.c
+++ b/drivers/media/cec/core/cec-pin-error-inj.c
@@ -91,6 +91,7 @@ bool cec_pin_error_inj_parse_line(struct cec_adapter *adap,
char *line)
if (!strcmp(token, "clear")) {
memset(pin->error_inj, 0, sizeof(pin->error_inj));
pin->rx_toggle = pin->tx_toggle = false;
+ pin->rx_no_low_drive = false;
pin->tx_ignore_nack_until_eom = false;
pin->tx_custom_pulse = false;
pin->tx_custom_low_usecs = CEC_TIM_CUSTOM_DEFAULT;
@@ -105,6 +106,7 @@ bool cec_pin_error_inj_parse_line(struct cec_adapter *adap,
char *line)
for (i = 0; i <= CEC_ERROR_INJ_OP_ANY; i++)
pin->error_inj[i] &= ~CEC_ERROR_INJ_RX_MASK;
pin->rx_toggle = false;
+ pin->rx_no_low_drive = false;
return true;
}
if (!strcmp(token, "tx-clear")) {
@@ -121,6 +123,10 @@ bool cec_pin_error_inj_parse_line(struct cec_adapter
*adap, char *line)
pin->tx_glitch_rising_edge = false;
return true;
}
+ if (!strcmp(token, "rx-no-low-drive")) {
+ pin->rx_no_low_drive = true;
+ return true;
+ }
if (!strcmp(token, "tx-ignore-nack-until-eom")) {
pin->tx_ignore_nack_until_eom = true;
return true;
@@ -305,6 +311,9 @@ int cec_pin_error_inj_show(struct cec_adapter *adap, struct
seq_file *sf)
seq_puts(sf, "# <op> rx-clear clear all rx error injections for
<op>\n");
seq_puts(sf, "# <op> tx-clear clear all tx error injections for
<op>\n");
seq_puts(sf, "#\n");
+ seq_puts(sf, "# RX error injection settings:\n");
+ seq_puts(sf, "# rx-no-low-drive do not generate
low-drive pulses\n");
+ seq_puts(sf, "#\n");
seq_puts(sf, "# RX error injection:\n");
seq_puts(sf, "# <op>[,<mode>] rx-nack NACK the message
instead of sending an ACK\n");
seq_puts(sf, "# <op>[,<mode>] rx-low-drive <bit> force a low-drive
condition at this bit position\n");
@@ -368,6 +377,8 @@ int cec_pin_error_inj_show(struct cec_adapter *adap, struct
seq_file *sf)
}
}
+ if (pin->rx_no_low_drive)
+ seq_puts(sf, "rx-no-low-drive\n");
if (pin->tx_ignore_nack_until_eom)
seq_puts(sf, "tx-ignore-nack-until-eom\n");
if (pin->tx_glitch_falling_edge)
diff --git a/drivers/media/cec/core/cec-pin-priv.h
b/drivers/media/cec/core/cec-pin-priv.h
index 88eefcb60ab8..e7801be9adb9 100644
--- a/drivers/media/cec/core/cec-pin-priv.h
+++ b/drivers/media/cec/core/cec-pin-priv.h
@@ -228,6 +228,7 @@ struct cec_pin {
u32 timer_max_overrun;
u32 timer_sum_overrun;
+ bool rx_no_low_drive;
u32 tx_custom_low_usecs;
u32 tx_custom_high_usecs;
u32 tx_glitch_low_usecs;
diff --git a/drivers/media/cec/core/cec-pin.c b/drivers/media/cec/core/cec-pin.c
index f3b0febf0f1c..4d7155281daa 100644
--- a/drivers/media/cec/core/cec-pin.c
+++ b/drivers/media/cec/core/cec-pin.c
@@ -797,7 +797,7 @@ static void cec_pin_rx_states(struct cec_pin *pin, ktime_t
ts)
* Go to low drive state when the total bit time is
* too short.
*/
- if (delta < CEC_TIM_DATA_BIT_TOTAL_MIN) {
+ if (delta < CEC_TIM_DATA_BIT_TOTAL_MIN &&
!pin->rx_no_low_drive) {
if (!pin->rx_data_bit_too_short_cnt++) {
pin->rx_data_bit_too_short_ts =
ktime_to_ns(pin->ts);
pin->rx_data_bit_too_short_delta = delta;
