Acked-by: Abylay Ospan <aospan@xxxxxxxx>
2017-04-09 15:38 GMT-04:00 Daniel Scheller <d.scheller.oss@xxxxxxxxx>:
> From: Daniel Scheller <d.scheller@xxxxxxx>
>
> 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 <d.scheller@xxxxxxx>
> ---
> 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 60d85ce..525d006 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,
> --
> 2.10.2
>
--
Abylay Ospan,
NetUP Inc.
http://www.netup.tv
