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Commit 5332b626 authored by Martin Wache's avatar Martin Wache Committed by Mauro Carvalho Chehab
Browse files

[media] dib7000p: avoid division by zero 



dib7000p_read_word() may return zero on i2c errors, resulting in
dib7000p_get_internal_freq() returning zero.
So don't divide by the result of dib7000p_get_internal_freq()
without checking it for zero in dib7000p_set_dds().

On one of my machines the device
ID 2304:0229 Pinnacle Systems, Inc. PCTV Dual DVB-T 2001e
about once a day/every two days gets into a state, where
most (all?) I2C reads return with an error. Tuning during this
state will result in a divide by zero without this patch.
This patch doesn't fix the root cause for the device getting
into a bad state, but it allows me to unload/reload the drivers,
bringing it back into a usable state.

Signed-off-by: default avatarMartin Wache <M.Wache@gmx.net>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@s-opensource.com>
parent 5610ced4

drivers/media/dvb-frontends/dib7000p.c

+12 −3
Original line number Diff line number Diff line
@@ -805,13 +805,19 @@ static int dib7000p_set_agc_config(struct dib7000p_state *state, u8 band) 
	return 0;

}



static void dib7000p_set_dds(struct dib7000p_state *state, s32 offset_khz)

static int dib7000p_set_dds(struct dib7000p_state *state, s32 offset_khz)

{

	u32 internal = dib7000p_get_internal_freq(state);

	s32 unit_khz_dds_val = 67108864 / (internal);	/* 2**26 / Fsampling is the unit 1KHz offset */

	s32 unit_khz_dds_val;

	u32 abs_offset_khz = ABS(offset_khz);

	u32 dds = state->cfg.bw->ifreq & 0x1ffffff;

	u8 invert = !!(state->cfg.bw->ifreq & (1 << 25));

	if (internal == 0) {

		pr_warn("DIB7000P: dib7000p_get_internal_freq returned 0\n");

		return -1;

	}

	/* 2**26 / Fsampling is the unit 1KHz offset */

	unit_khz_dds_val = 67108864 / (internal);



	dprintk("setting a frequency offset of %dkHz internal freq = %d invert = %d\n", offset_khz, internal, invert);
@@ -828,6 +834,7 @@ static void dib7000p_set_dds(struct dib7000p_state *state, s32 offset_khz) 
		dib7000p_write_word(state, 21, (u16) (((dds >> 16) & 0x1ff) | (0 << 10) | (invert << 9)));

		dib7000p_write_word(state, 22, (u16) (dds & 0xffff));

	}

	return 0;

}



static int dib7000p_agc_startup(struct dvb_frontend *demod)
@@ -867,7 +874,9 @@ static int dib7000p_agc_startup(struct dvb_frontend *demod) 
			frequency_offset = (s32)frequency_tuner / 1000 - ch->frequency / 1000;

		}



		dib7000p_set_dds(state, frequency_offset);

		if (dib7000p_set_dds(state, frequency_offset) < 0)

			return -1;



		ret = 7;

		(*agc_state)++;

		break;