On Sun Aug 30 17:08:47 2026 +0000, Alberto Pimpo wrote:
> The lists of frequencies the simulated tuner locks onto are module
> parameters, and were handed over to the tuner module without being
> checked first.
>
> A terrestrial or cable frequency outside the range the demodulator
> reports to the DVB core is unreachable, as dvb_frontend_check_parameters()
> rejects such a tuning request before the tuner is ever asked about the
> frequency. A satellite frequency outside the Ku-band covered by the
> simulated LNBf is equally meaningless, since it is downconverted using
> the LNBf local oscillators before reaching the tuner.
>
> In both cases vidtv used to initialize successfully and then never lock
> on anything, leaving no clue about the cause.
>
> Check the terrestrial and cable frequencies against the range advertised
> by the demodulator, and the satellite ones against the Ku-band covered by
> the simulated LNBf, failing the probe with an explicit error message
> otherwise.
>
> Signed-off-by: Alberto Pimpo <[email protected]>
> Signed-off-by: Hans Verkuil <[email protected]>
Patch committed.
Thanks,
Hans Verkuil
drivers/media/test-drivers/vidtv/vidtv_bridge.c | 71 ++++++++++++++++++++++++-
1 file changed, 70 insertions(+), 1 deletion(-)
---
diff --git a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
index f951b877ada6..4c98dfbd406f 100644
--- a/drivers/media/test-drivers/vidtv/vidtv_bridge.c
+++ b/drivers/media/test-drivers/vidtv/vidtv_bridge.c
@@ -44,6 +44,10 @@
#define LNB_LOW_FREQ 9750000 /* low IF frequency */
#define LNB_HIGH_FREQ 10600000 /* transition frequency */
+/* The Ku-band range covered by such an LNBf, in kHz */
+#define LNB_KU_BAND_MIN_FREQ 10700000
+#define LNB_KU_BAND_MAX_FREQ 12750000
+
static unsigned int drop_tslock_prob_on_low_snr;
module_param(drop_tslock_prob_on_low_snr, uint, 0444);
MODULE_PARM_DESC(drop_tslock_prob_on_low_snr,
@@ -367,6 +371,36 @@ static int vidtv_bridge_probe_demod(struct vidtv_dvb *dvb,
u32 n)
return 0;
}
+/*
+ * Reject frequencies the simulation could never tune into, as the module
+ * would otherwise load just fine and then never lock on anything, leaving
+ * no clue about what went wrong.
+ */
+static int vidtv_bridge_check_freqs(struct vidtv_dvb *dvb,
+ const unsigned int *freqs,
+ u32 array_sz,
+ u32 min_freq,
+ u32 max_freq,
+ const char *name)
+{
+ u32 i;
+
+ for (i = 0; i < array_sz; i++) {
+ /* a zeroed entry means an unused slot */
+ if (!freqs[i])
+ continue;
+
+ if (freqs[i] < min_freq || freqs[i] > max_freq) {
+ dev_err(&dvb->pdev->dev,
+ "%s[%u]: %u is out of range (%u..%u)\n",
+ name, i, freqs[i], min_freq, max_freq);
+ return -EINVAL;
+ }
+ }
+
+ return 0;
+}
+
static int vidtv_bridge_probe_tuner(struct vidtv_dvb *dvb, u32 n)
{
struct vidtv_tuner_config cfg = {
@@ -374,10 +408,45 @@ static int vidtv_bridge_probe_tuner(struct vidtv_dvb
*dvb, u32 n)
.mock_power_up_delay_msec = mock_power_up_delay_msec,
.mock_tune_delay_msec = mock_tune_delay_msec,
};
+ u32 min_freq = dvb->fe[n]->ops.info.frequency_min_hz;
+ u32 max_freq = dvb->fe[n]->ops.info.frequency_max_hz;
u32 freq;
+ int ret;
int i;
- /* TODO: check if the frequencies are at a valid range */
+ /*
+ * Terrestrial and cable frequencies are given in Hz and are used as
+ * is, so they have to fit within the range the demod reports to the
+ * DVB core: the core rejects a tuning request outside of it before
+ * the tuner is ever asked about the frequency.
+ */
+ ret = vidtv_bridge_check_freqs(dvb, vidtv_valid_dvb_t_freqs,
+ ARRAY_SIZE(vidtv_valid_dvb_t_freqs),
+ min_freq, max_freq,
+ "vidtv_valid_dvb_t_freqs");
+ if (ret)
+ return ret;
+
+ ret = vidtv_bridge_check_freqs(dvb, vidtv_valid_dvb_c_freqs,
+ ARRAY_SIZE(vidtv_valid_dvb_c_freqs),
+ min_freq, max_freq,
+ "vidtv_valid_dvb_c_freqs");
+ if (ret)
+ return ret;
+
+ /*
+ * Satellite frequencies are given in kHz at Ku-band and are
+ * downconverted below, so check them against the band the simulated
+ * LNBf covers instead. Doing so also ensures that the frequencies
+ * are above the LNBf local oscillators.
+ */
+ ret = vidtv_bridge_check_freqs(dvb, vidtv_valid_dvb_s_freqs,
+ ARRAY_SIZE(vidtv_valid_dvb_s_freqs),
+ LNB_KU_BAND_MIN_FREQ,
+ LNB_KU_BAND_MAX_FREQ,
+ "vidtv_valid_dvb_s_freqs");
+ if (ret)
+ return ret;
memcpy(cfg.vidtv_valid_dvb_t_freqs,
vidtv_valid_dvb_t_freqs,
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