From 5332b6263742cd75963eccdea9e3af4a464c2999 Mon Sep 17 00:00:00 2001 From: Martin Wache Date: Tue, 13 Dec 2016 18:21:41 -0200 Subject: [PATCH] [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 Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/dib7000p.c | 15 ++++++++++++--- 1 file 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; -- 2.20.1