[PATCH AUTOSEL 5.4 003/109] media: dib8000: rewrite the init prbs logic

Sasha Levin
2021-09-09T12:56:55Z

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

[ Upstream commit 8db11aebdb8f93f46a8513c22c9bd52fa23263aa ]

The logic at dib8000_get_init_prbs() has a few issues:

1. the tables used there has an extra unused value at the beginning;
2. the dprintk() message doesn't write the right value when
transmission mode is not 8K;
3. the array overflow validation is done by the callers.

Rewrite the code to fix such issues.

This should also shut up those smatch warnings:

drivers/media/dvb-frontends/dib8000.c:2125 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_8k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2129 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_2k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2131 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_4k' 14 <= 14
drivers/media/dvb-frontends/dib8000.c:2134 dib8000_get_init_prbs() error: buffer overflow 'lut_prbs_8k' 14 <= 14

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/media/dvb-frontends/dib8000.c | 58 +++++++++++++++++++--------
1 file changed, 41 insertions(+), 17 deletions(-)

diff --git a/drivers/media/dvb-frontends/dib8000.c b/drivers/media/dvb-frontends/dib8000.c
index 082796534b0a..bb02354a48b8 100644
--- a/drivers/media/dvb-frontends/dib8000.c
+++ b/drivers/media/dvb-frontends/dib8000.c
@@ -2107,32 +2107,55 @@ static void dib8000_load_ana_fe_coefs(struct dib8000_state *state, const s16 *an
dib8000_write_word(state, 117 + mode, ana_fe[mode]);
}

-static const u16 lut_prbs_2k[14] = {
- 0, 0x423, 0x009, 0x5C7, 0x7A6, 0x3D8, 0x527, 0x7FF, 0x79B, 0x3D6, 0x3A2, 0x53B, 0x2F4, 0x213
+static const u16 lut_prbs_2k[13] = {
+ 0x423, 0x009, 0x5C7,
+ 0x7A6, 0x3D8, 0x527,
+ 0x7FF, 0x79B, 0x3D6,
+ 0x3A2, 0x53B, 0x2F4,
+ 0x213
};
-static const u16 lut_prbs_4k[14] = {
- 0, 0x208, 0x0C3, 0x7B9, 0x423, 0x5C7, 0x3D8, 0x7FF, 0x3D6, 0x53B, 0x213, 0x029, 0x0D0, 0x48E
+
+static const u16 lut_prbs_4k[13] = {
+ 0x208, 0x0C3, 0x7B9,
+ 0x423, 0x5C7, 0x3D8,
+ 0x7FF, 0x3D6, 0x53B,
+ 0x213, 0x029, 0x0D0,
+ 0x48E
};
-static const u16 lut_prbs_8k[14] = {
- 0, 0x740, 0x069, 0x7DD, 0x208, 0x7B9, 0x5C7, 0x7FF, 0x53B, 0x029, 0x48E, 0x4C4, 0x367, 0x684
+
+static const u16 lut_prbs_8k[13] = {
+ 0x740, 0x069, 0x7DD,
+ 0x208, 0x7B9, 0x5C7,
+ 0x7FF, 0x53B, 0x029,
+ 0x48E, 0x4C4, 0x367,
+ 0x684
};

static u16 dib8000_get_init_prbs(struct dib8000_state *state, u16 subchannel)
{
int sub_channel_prbs_group = 0;
+ int prbs_group;

- sub_channel_prbs_group = (subchannel / 3) + 1;
- dprintk("sub_channel_prbs_group = %d , subchannel =%d prbs = 0x%04x\n", sub_channel_prbs_group, subchannel, lut_prbs_8k[sub_channel_prbs_group]);
+ sub_channel_prbs_group = subchannel / 3;
+ if (sub_channel_prbs_group >= ARRAY_SIZE(lut_prbs_2k))
+ return 0;

switch (state->fe[0]->dtv_property_cache.transmission_mode) {
case TRANSMISSION_MODE_2K:
- return lut_prbs_2k[sub_channel_prbs_group];
+ prbs_group = lut_prbs_2k[sub_channel_prbs_group];
+ break;
case TRANSMISSION_MODE_4K:
- return lut_prbs_4k[sub_channel_prbs_group];
+ prbs_group = lut_prbs_4k[sub_channel_prbs_group];
+ break;
default:
case TRANSMISSION_MODE_8K:
- return lut_prbs_8k[sub_channel_prbs_group];
+ prbs_group = lut_prbs_8k[sub_channel_prbs_group];
}
+
+ dprintk("sub_channel_prbs_group = %d , subchannel =%d prbs = 0x%04x\n",
+ sub_channel_prbs_group, subchannel, prbs_group);
+
+ return prbs_group;
}

static void dib8000_set_13seg_channel(struct dib8000_state *state)
@@ -2409,10 +2432,8 @@ static void dib8000_set_isdbt_common_channel(struct dib8000_state *state, u8 seq
/* TSB or ISDBT ? apply it now */
if (c->isdbt_sb_mode) {
dib8000_set_sb_channel(state);
- if (c->isdbt_sb_subchannel < 14)
- init_prbs = dib8000_get_init_prbs(state, c->isdbt_sb_subchannel);
- else
- init_prbs = 0;
+ init_prbs = dib8000_get_init_prbs(state,
+ c->isdbt_sb_subchannel);
} else {
dib8000_set_13seg_channel(state);
init_prbs = 0xfff;
@@ -3004,6 +3025,7 @@ static int dib8000_tune(struct dvb_frontend *fe)

unsigned long *timeout = &state->timeout;
unsigned long now = jiffies;
+ u16 init_prbs;
#ifdef DIB8000_AGC_FREEZE
u16 agc1, agc2;
#endif
@@ -3302,8 +3324,10 @@ static int dib8000_tune(struct dvb_frontend *fe)
break;

case CT_DEMOD_STEP_11: /* 41 : init prbs autosearch */
- if (state->subchannel <= 41) {
- dib8000_set_subchannel_prbs(state, dib8000_get_init_prbs(state, state->subchannel));
+ init_prbs = dib8000_get_init_prbs(state, state->subchannel);
+
+ if (init_prbs) {
+ dib8000_set_subchannel_prbs(state, init_prbs);
*tune_state = CT_DEMOD_STEP_9;
} else {
*tune_state = CT_DEMOD_STOP;
--
2.30.2