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authorMartin Wache <M.Wache@gmx.net>2016-12-13 18:21:41 -0200
committerMauro Carvalho Chehab <mchehab@s-opensource.com>2017-02-03 10:54:20 -0200
commit5332b6263742cd75963eccdea9e3af4a464c2999 (patch)
tree90b31c76e4dbccd2adedcbb727c3a8acc50ec11f /drivers/media/dvb-frontends/dib7000p.c
parent5610ced4f13d5d864773ee2aa63e7cd9c3ca1c04 (diff)
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[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: Martin Wache <M.Wache@gmx.net> Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'drivers/media/dvb-frontends/dib7000p.c')
-rw-r--r--drivers/media/dvb-frontends/dib7000p.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/media/dvb-frontends/dib7000p.c b/drivers/media/dvb-frontends/dib7000p.c
index a27c0001f2d6..3815ea515364 100644
--- a/drivers/media/dvb-frontends/dib7000p.c
+++ b/drivers/media/dvb-frontends/dib7000p.c
@@ -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;