From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-ea0-f174.google.com ([209.85.215.174]:49846 "EHLO mail-ea0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754494AbaAASvE (ORCPT ); Wed, 1 Jan 2014 13:51:04 -0500 Received: by mail-ea0-f174.google.com with SMTP id b10so5856677eae.5 for ; Wed, 01 Jan 2014 10:51:02 -0800 (PST) Message-ID: <52C463D8.7020406@googlemail.com> Date: Wed, 01 Jan 2014 19:52:08 +0100 From: =?ISO-8859-15?Q?Frank_Sch=E4fer?= MIME-Version: 1.0 To: Mauro Carvalho Chehab CC: unlisted-recipients:; Mauro Carvalho Chehab , Linux Media Mailing List , Mauro Carvalho Chehab Subject: Re: [PATCH v3 11/24] tvp5150: make read operations atomic References: <1388232976-20061-1-git-send-email-mchehab@redhat.com> <1388232976-20061-12-git-send-email-mchehab@redhat.com> In-Reply-To: <1388232976-20061-12-git-send-email-mchehab@redhat.com> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Am 28.12.2013 13:16, schrieb Mauro Carvalho Chehab: > From: Mauro Carvalho Chehab > > Instead of using two I2C operations between write and read, > use just one i2c_transfer. That allows I2C mutexes to not > let any other I2C transfer between the two. > > Signed-off-by: Mauro Carvalho Chehab > --- > drivers/media/i2c/tvp5150.c | 22 ++++++++++------------ > 1 file changed, 10 insertions(+), 12 deletions(-) > > diff --git a/drivers/media/i2c/tvp5150.c b/drivers/media/i2c/tvp5150.c > index 89c0b13463b7..d6ba457fcf67 100644 > --- a/drivers/media/i2c/tvp5150.c > +++ b/drivers/media/i2c/tvp5150.c > @@ -58,21 +58,19 @@ static int tvp5150_read(struct v4l2_subdev *sd, unsigned char addr) > struct i2c_client *c = v4l2_get_subdevdata(sd); > unsigned char buffer[1]; > int rc; > + struct i2c_msg msg[] = { > + { .addr = c->addr, .flags = 0, > + .buf = &addr, .len = 1 }, I would use .buf = buffer here, too. > + { .addr = c->addr, .flags = I2C_M_RD, > + .buf = buffer, .len = 1 } > + }; > > buffer[0] = addr; > > - rc = i2c_master_send(c, buffer, 1); > - if (rc < 0) { > - v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc); > - return rc; > - } > - > - msleep(10); That's the critical change. > - > - rc = i2c_master_recv(c, buffer, 1); > - if (rc < 0) { > - v4l2_err(sd, "i2c i/o error: rc == %d (should be 1)\n", rc); > - return rc; > + rc = i2c_transfer(c->adapter, msg, 2); > + if (rc < 0 || rc != 2) { > + v4l2_err(sd, "i2c i/o error: rc == %d (should be 2)\n", rc); > + return rc < 0 ? rc : -EIO; > } > > v4l2_dbg(2, debug, sd, "tvp5150: read 0x%02x = 0x%02x\n", addr, buffer[0]); Looks good and works without problems with my HVR-900 and WinTV 2 devices (both em28xx).