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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: Daniel Scally <djrscally@gmail.com>,
	devel@driverdev.osuosl.org, robh@kernel.org,
	andriy.shevchenko@linux.intel.com, jorhand@linux.microsoft.com,
	linux-media@vger.kernel.org, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, kieran.bingham@ideasonboard.com,
	kitakar@gmail.com, bingbu.cao@intel.com, mchehab@kernel.org,
	davem@davemloft.net, tian.shu.qiu@intel.com, yong.zhi@intel.com
Subject: Re: [RFC PATCH] Add bridge driver to connect sensors to CIO2 device via software nodes on ACPI platforms
Date: Thu, 17 Sep 2020 13:49:41 +0300	[thread overview]
Message-ID: <20200917104941.GP4282@kadam> (raw)
In-Reply-To: <20200917103343.GW26842@paasikivi.fi.intel.com>

On Thu, Sep 17, 2020 at 01:33:43PM +0300, Sakari Ailus wrote:
> > +static int connect_supported_devices(void)
> > +{
> > +	struct acpi_device *adev;
> > +	struct device *dev;
> > +	struct sensor_bios_data ssdb;
> > +	struct sensor *sensor;
> > +	struct property_entry *sensor_props;
> > +	struct property_entry *cio2_props;
> > +	struct fwnode_handle *fwnode;
> > +	struct software_node *nodes;
> > +	struct v4l2_subdev *sd;
> > +	int i, ret;
> 
> unsigned int i
> 

Why?

For list iterators then "int i;" is best...  For sizes then unsigned is
sometimes best.  Or if it's part of the hardware spec or network spec
unsigned is best.  Otherwise unsigned variables cause a ton of bugs.
They're not as intuitive as signed variables.  Imagine if there is an
error in this loop and you want to unwind.  With a signed variable you
can do:

	while (--i >= 0)
		cleanup(&bridge.sensors[i]);

There are very few times where raising the type maximum from 2 billion
to 4 billion fixes anything.

regards,
dan carpenter


WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Sakari Ailus <sakari.ailus@linux.intel.com>
Cc: devel@driverdev.osuosl.org, robh@kernel.org, mchehab@kernel.org,
	jorhand@linux.microsoft.com, gregkh@linuxfoundation.org,
	linux-kernel@vger.kernel.org, kieran.bingham@ideasonboard.com,
	Daniel Scally <djrscally@gmail.com>,
	kitakar@gmail.com, yong.zhi@intel.com, bingbu.cao@intel.com,
	andriy.shevchenko@linux.intel.com, davem@davemloft.net,
	tian.shu.qiu@intel.com, linux-media@vger.kernel.org
Subject: Re: [RFC PATCH] Add bridge driver to connect sensors to CIO2 device via software nodes on ACPI platforms
Date: Thu, 17 Sep 2020 13:49:41 +0300	[thread overview]
Message-ID: <20200917104941.GP4282@kadam> (raw)
In-Reply-To: <20200917103343.GW26842@paasikivi.fi.intel.com>

On Thu, Sep 17, 2020 at 01:33:43PM +0300, Sakari Ailus wrote:
> > +static int connect_supported_devices(void)
> > +{
> > +	struct acpi_device *adev;
> > +	struct device *dev;
> > +	struct sensor_bios_data ssdb;
> > +	struct sensor *sensor;
> > +	struct property_entry *sensor_props;
> > +	struct property_entry *cio2_props;
> > +	struct fwnode_handle *fwnode;
> > +	struct software_node *nodes;
> > +	struct v4l2_subdev *sd;
> > +	int i, ret;
> 
> unsigned int i
> 

Why?

For list iterators then "int i;" is best...  For sizes then unsigned is
sometimes best.  Or if it's part of the hardware spec or network spec
unsigned is best.  Otherwise unsigned variables cause a ton of bugs.
They're not as intuitive as signed variables.  Imagine if there is an
error in this loop and you want to unwind.  With a signed variable you
can do:

	while (--i >= 0)
		cleanup(&bridge.sensors[i]);

There are very few times where raising the type maximum from 2 billion
to 4 billion fixes anything.

regards,
dan carpenter

_______________________________________________
devel mailing list
devel@linuxdriverproject.org
http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel

  reply	other threads:[~2020-09-17 10:54 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-16 21:36 [RFC PATCH] Add bridge driver to connect sensors to CIO2 device via software nodes on ACPI platforms Daniel Scally
2020-09-16 21:36 ` Daniel Scally
2020-09-17  0:17 ` kernel test robot
2020-09-17  3:02 ` kernel test robot
2020-09-17  7:53 ` Greg KH
2020-09-17  7:53   ` Greg KH
2020-09-17  9:47   ` Dan Scally
2020-09-17  9:47     ` Dan Scally
2020-09-17 10:15     ` Dan Carpenter
2020-09-17 10:15       ` Dan Carpenter
2020-09-17 10:24       ` Dan Scally
2020-09-17 10:24         ` Dan Scally
2020-09-17 13:28     ` Kieran Bingham
2020-09-17 13:28       ` Kieran Bingham
2020-09-17 14:08       ` Andy Shevchenko
2020-09-17 14:08         ` Andy Shevchenko
2020-09-17 14:19         ` Kieran Bingham
2020-09-17 14:19           ` Kieran Bingham
2020-09-17 14:36           ` Andy Shevchenko
2020-09-17 14:36             ` Andy Shevchenko
2020-09-17  9:34 ` Dan Carpenter
2020-09-17  9:34   ` Dan Carpenter
2020-09-17 10:19   ` Joe Perches
2020-09-17 10:19     ` Joe Perches
2020-09-18 22:50   ` Dan Scally
2020-09-18 22:50     ` Dan Scally
2020-09-17 10:33 ` Sakari Ailus
2020-09-17 10:33   ` Sakari Ailus
2020-09-17 10:49   ` Dan Carpenter [this message]
2020-09-17 10:49     ` Dan Carpenter
2020-09-17 12:25     ` Andy Shevchenko
2020-09-17 12:25       ` Andy Shevchenko
2020-09-17 13:15       ` Dan Carpenter
2020-09-17 13:15         ` Dan Carpenter
2020-09-18  6:40     ` Sakari Ailus
2020-09-18  6:40       ` Sakari Ailus
2020-09-18  8:16       ` Dan Carpenter
2020-09-18  8:16         ` Dan Carpenter
2020-09-17 10:52   ` Dan Scally
2020-09-17 10:52     ` Dan Scally
2020-09-17 12:45     ` Andy Shevchenko
2020-09-17 12:45       ` Andy Shevchenko
2020-09-17 13:36       ` Dan Scally
2020-09-17 13:36         ` Dan Scally
2020-09-17 14:14         ` Andy Shevchenko
2020-09-17 14:14           ` Andy Shevchenko
2020-09-17 21:25           ` Daniel Scally
2020-09-17 21:25             ` Daniel Scally
2020-09-17 14:44         ` Andy Shevchenko
2020-09-17 14:44           ` Andy Shevchenko
2020-09-18  7:51       ` Sakari Ailus
2020-09-18  7:51         ` Sakari Ailus
2020-09-18 13:07         ` Andy Shevchenko
2020-09-18 13:07           ` Andy Shevchenko
2020-09-21 13:33           ` Dan Scally
2020-09-21 13:33             ` Dan Scally
2020-09-21 14:33             ` Andy Shevchenko
2020-09-21 14:33               ` Andy Shevchenko
2020-09-23  9:39   ` Dan Scally
2020-09-23  9:39     ` Dan Scally
2020-09-28 11:37   ` Dan Scally
2020-09-28 11:37     ` Dan Scally
2020-09-18  8:03 ` Dan Carpenter
2020-09-18  8:03   ` Dan Carpenter
2020-09-18  8:09   ` Dan Scally
2020-09-18  8:09     ` Dan Scally
2020-09-20 21:34 ` kernel test robot
2020-09-20 21:34 ` [RFC PATCH] cio2_sync_state() can be static kernel test robot

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