From: Guenter Roeck <linux@roeck-us.net>
To: "José Miguel Gonçalves" <jose.goncalves@inov.pt>,
"Jean Delvare" <khali@linux-fr.org>,
"Guenter Roeck" <guenter.roeck@ericsson.com>,
lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org
Subject: Re: [lm-sensors] [PATCH] hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK
Date: Wed, 11 Dec 2013 01:28:04 +0000 [thread overview]
Message-ID: <52A7BFA4.2080402@roeck-us.net> (raw)
In-Reply-To: <1386723462-21388-1-git-send-email-jose.goncalves@inov.pt>
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WARNING: multiple messages have this Message-ID (diff)
From: Guenter Roeck <linux@roeck-us.net>
To: "José Miguel Gonçalves" <jose.goncalves@inov.pt>,
"Jean Delvare" <khali@linux-fr.org>,
"Guenter Roeck" <guenter.roeck@ericsson.com>,
lm-sensors@lm-sensors.org, linux-kernel@vger.kernel.org
Subject: Re: [lm-sensors] [PATCH] hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK
Date: Tue, 10 Dec 2013 17:28:04 -0800 [thread overview]
Message-ID: <52A7BFA4.2080402@roeck-us.net> (raw)
In-Reply-To: <1386723462-21388-1-git-send-email-jose.goncalves@inov.pt>
On 12/10/2013 04:57 PM, José Miguel Gonçalves wrote:
> Some I2C bus drivers do not allow zero-lenght data transfers which are
s/lenght/length/
> required to start a mesurement with the HIH6130/1 sensor. Nevertheless,
s/mesurement/measurement/
> we can overcome this limitation by writing a zero dummy byte. This byte
> is ignored by the sensor and was verified to be working with the OMAP
> I2C bus driver in a BeagleBone board.
>
> Signed-off-by: José Miguel Gonçalves <jose.goncalves@inov.pt>
> ---
> drivers/hwmon/hih6130.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hwmon/hih6130.c b/drivers/hwmon/hih6130.c
> index 2dc37c7..a860cc4 100644
> --- a/drivers/hwmon/hih6130.c
> +++ b/drivers/hwmon/hih6130.c
> @@ -121,8 +121,20 @@ static int hih6130_update_measurements(struct i2c_client *client)
> */
> if (time_after(jiffies, hih6130->last_update + HZ) || !hih6130->valid) {
>
> - /* write to slave address, no data, to request a measurement */
> - ret = i2c_master_send(client, tmp, 0);
> + /*
> + * Write to slave address, to request a measurement.
s/,//
> + * According with the datasheet it should be with no data, but
> + * for systems with I2C bus drivers that do not allow zero
> + * length packets we write one dummy byte to allow sensor
> + * measurements on them.
> + */
> + if (i2c_get_functionality(client->adapter) &
> + I2C_FUNC_SMBUS_QUICK) {
> + ret = i2c_master_send(client, tmp, 0);
> + } else {
> + tmp[0] = 0;
> + ret = i2c_master_send(client, tmp, 1);
> + }
You can simplify this code by introducing a variable to hold
the write length into struct hih6130. This variable can be
initialized with 1 or 0 in the probe function.
if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_QUICK))
hih6130->write_length = 0;
else
hih6130->write_length = 1;
Then replace above code with
tmp[0] = 0;
ret = i2c_master_send(client, tmp, hih6130->write_length);
This way you don't have to call i2c_{get,check}_functionality() repeatedly.
Thanks,
Guenter
> if (ret < 0)
> goto out;
>
>
next prev parent reply other threads:[~2013-12-11 1:28 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-11 0:57 [lm-sensors] [PATCH] hwmon: HIH-6130: Support I2C bus drivers without I2C_FUNC_SMBUS_QUICK José Miguel Gonçalves
2013-12-11 0:57 ` José Miguel Gonçalves
2013-12-11 1:28 ` Guenter Roeck [this message]
2013-12-11 1:28 ` [lm-sensors] " Guenter Roeck
2013-12-11 11:11 ` José Miguel Gonçalves
2013-12-11 11:11 ` José Miguel Gonçalves
2013-12-11 19:29 ` [lm-sensors] " Guenter Roeck
2013-12-11 19:29 ` Guenter Roeck
2013-12-11 19:51 ` [lm-sensors] " José Miguel Gonçalves
2013-12-11 19:51 ` José Miguel Gonçalves
2013-12-11 21:28 ` [lm-sensors] " Guenter Roeck
2013-12-11 21:28 ` Guenter Roeck
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