media: vidtv: adjust signal strength range (d859a712) · Commits · 戴 / test

On real devices, signal strength is always a negative number when represented in dBm. A more interesting range is to use dBmV (which is what Kaffeine does, for example). The conversion from the two units are simple: dBmV = dBm - 108 Usually, signal strength ranges up to 100dBmV. Adjust the maximum value to be around 74 dBmV, when there's no frequency shift, which represents a good signal. With that, Kaffeine displays it a lot better. Signed-off-by:

Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/test-drivers/vidtv/vidtv_demod.c

+9 −3

Original line number	Diff line number	Diff line
		@@ -181,12 +181,18 @@ static void vidtv_demod_update_stats(struct dvb_frontend *fe)
		c->block_count.stat[0].scale = scale;

		/*
		* Add a 0.5% of randomness at the signal streangth and CNR,
		* Add a 0.5% of randomness at the signal strength and CNR,
		* and make them different, as we want to have something closer
		* to a real case scenario.
		*
		* Also, usually, signal strength is a negative number in dBm.
		*/
		c->strength.stat[0].svalue = state->tuner_cnr + prandom_u32_max(state->tuner_cnr / 50);
		c->cnr.stat[0].svalue = state->tuner_cnr - prandom_u32_max(state->tuner_cnr / 50);
		c->strength.stat[0].svalue = state->tuner_cnr;
		c->strength.stat[0].svalue -= prandom_u32_max(state->tuner_cnr / 50);
		c->strength.stat[0].svalue -= 68000; /* Adjust to a better range */

		c->cnr.stat[0].svalue = state->tuner_cnr;
		c->cnr.stat[0].svalue -= prandom_u32_max(state->tuner_cnr / 50);

		}

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