Re: [ragnatech:media-tree 2075/2144] drivers/media/dvb-frontends/stv0910.c:1185:2-8: preceding lock on line 1176 (fwd)

[Daniel Scheller]

Hello Jula,

Am 24.07.2017 um 07:02 schrieb Julia Lawall:
Is a lock release needed before line 1185?  Is the !enable in line 1189
correct?  If the code is correct as is, perhaps it could be good to add
some comments.

Yes, it's needed because the I2C gate is shared for the two tuner chips 
attached to it (one dual-demod chip -> two tuners/SECs) and the bus 
access needs to be protected to not accidentally interfere when 
accessing both tuners in parallel.

I'll think about proper comments there.

Thanks,
Daniel

---------- Forwarded message ----------
Date: Mon, 24 Jul 2017 12:55:30 +0800
From: kbuild test robot <fengguang...@intel.com>
To: kbu...@01.org
Cc: Julia Lawall <julia.law...@lip6.fr>
Subject: [ragnatech:media-tree 2075/2144]
     drivers/media/dvb-frontends/stv0910.c:1185:2-8: preceding lock on line 1176

CC: kbuild-...@01.org
TO: Daniel Scheller <d.schel...@gmx.net>
CC: Mauro Carvalho Chehab <m.che...@samsung.com>
CC: linux-media@vger.kernel.org

tree:   git://git.ragnatech.se/linux media-tree
head:   0e50e84a11f4854e9a7e3b7f4443ffb99e6be292
commit: cd21b334943719f880e707eb91895fc916a88000 [2075/2144] media: 
dvb-frontends: add ST STV0910 DVB-S/S2 demodulator frontend driver
:::::: branch date: 3 days ago
:::::: commit date: 4 days ago

drivers/media/dvb-frontends/stv0910.c:1185:2-8: preceding lock on line 1176

git remote add ragnatech git://git.ragnatech.se/linux
git remote update ragnatech
git checkout cd21b334943719f880e707eb91895fc916a88000
vim +1185 drivers/media/dvb-frontends/stv0910.c

cd21b334 Daniel Scheller 2017-07-03  1168
cd21b334 Daniel Scheller 2017-07-03  1169
cd21b334 Daniel Scheller 2017-07-03  1170  static int gate_ctrl(struct 
dvb_frontend *fe, int enable)
cd21b334 Daniel Scheller 2017-07-03  1171  {
cd21b334 Daniel Scheller 2017-07-03  1172       struct stv *state = 
fe->demodulator_priv;
cd21b334 Daniel Scheller 2017-07-03  1173       u8 i2crpt = state->i2crpt & 
~0x86;
cd21b334 Daniel Scheller 2017-07-03  1174
cd21b334 Daniel Scheller 2017-07-03  1175       if (enable)
cd21b334 Daniel Scheller 2017-07-03 @1176               
mutex_lock(&state->base->i2c_lock);
cd21b334 Daniel Scheller 2017-07-03  1177
cd21b334 Daniel Scheller 2017-07-03  1178       if (enable)
cd21b334 Daniel Scheller 2017-07-03  1179               i2crpt |= 0x80;
cd21b334 Daniel Scheller 2017-07-03  1180       else
cd21b334 Daniel Scheller 2017-07-03  1181               i2crpt |= 0x02;
cd21b334 Daniel Scheller 2017-07-03  1182
cd21b334 Daniel Scheller 2017-07-03  1183       if (write_reg(state, state->nr 
? RSTV0910_P2_I2CRPT :
cd21b334 Daniel Scheller 2017-07-03  1184                     RSTV0910_P1_I2CRPT, 
i2crpt) < 0)
cd21b334 Daniel Scheller 2017-07-03 @1185               return -EIO;
cd21b334 Daniel Scheller 2017-07-03  1186
cd21b334 Daniel Scheller 2017-07-03  1187       state->i2crpt = i2crpt;
cd21b334 Daniel Scheller 2017-07-03  1188
cd21b334 Daniel Scheller 2017-07-03  1189       if (!enable)
cd21b334 Daniel Scheller 2017-07-03  1190               
mutex_unlock(&state->base->i2c_lock);
cd21b334 Daniel Scheller 2017-07-03  1191       return 0;
cd21b334 Daniel Scheller 2017-07-03  1192  }
cd21b334 Daniel Scheller 2017-07-03  1193

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Best regards,
Daniel Scheller
--
https://github.com/herrnst