From 725e93eba1769b61545da06366be908eedd688a0 Mon Sep 17 00:00:00 2001 From: Daniel Scheller Date: Sun, 9 Apr 2017 16:38:11 -0300 Subject: [PATCH] [media] dvb-frontends/cxd2841er: do I2C reads in one go Doing the I2C read operation with two calls to i2c_transfer() causes the exclusive I2C bus lock of the underlying adapter to be released. While this isn't an issue if only one demodulator is attached to the bus, having two or even more causes troubles in that concurrent accesses to the different demods will cause all kinds of issues due to wrong data being returned on read operations (for example, the TS config register will be set wrong). This changes the read_regs() function to do the operation in one go (by calling i2c_transfer with the whole msg list instead of one by one) to not loose the I2C bus lock, fixing all sorts of random runtime failures. Signed-off-by: Daniel Scheller Acked-by: Abylay Ospan Signed-off-by: Mauro Carvalho Chehab --- drivers/media/dvb-frontends/cxd2841er.c | 13 ++----------- 1 file changed, 2 insertions(+), 11 deletions(-) diff --git a/drivers/media/dvb-frontends/cxd2841er.c b/drivers/media/dvb-frontends/cxd2841er.c index b06a8a212279..575d08ad2be3 100644 --- a/drivers/media/dvb-frontends/cxd2841er.c +++ b/drivers/media/dvb-frontends/cxd2841er.c @@ -282,17 +282,8 @@ static int cxd2841er_read_regs(struct cxd2841er_priv *priv, } }; - ret = i2c_transfer(priv->i2c, &msg[0], 1); - if (ret >= 0 && ret != 1) - ret = -EIO; - if (ret < 0) { - dev_warn(&priv->i2c->dev, - "%s: i2c rw failed=%d addr=%02x reg=%02x\n", - KBUILD_MODNAME, ret, i2c_addr, reg); - return ret; - } - ret = i2c_transfer(priv->i2c, &msg[1], 1); - if (ret >= 0 && ret != 1) + ret = i2c_transfer(priv->i2c, msg, 2); + if (ret >= 0 && ret != 2) ret = -EIO; if (ret < 0) { dev_warn(&priv->i2c->dev, -- 2.20.1