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[media] dib7000p: avoid division by zero

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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: Martin Wache <M.Wache@gmx.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Martin Wache 2016-12-13 18:21:41 -02:00 committed by Mauro Carvalho Chehab
parent 5610ced4f1
commit 5332b62637
1 changed files with 12 additions and 3 deletions
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15
drivers/media/dvb-frontends/dib7000p.c
View file

@ -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;