Re: [PATCH v3 05/25] leds: core: Add support for composing LED class device names

[Jacek Anaszewski]

Hi Dan,

Thank you for the review.

On 4/5/19 1:45 PM, Dan Murphy wrote:
> Jacek
>
> On 3/31/19 12:54 PM, Jacek Anaszewski wrote:
> > Add generic support for composing LED class device name basing on
> > fwnode_handle data. The function composes device name according to
> > either a new <color:function> pattern or the legacy
> > <devicename:color:function> pattern. The decision on using the
> > particular pattern is made basing on whether fwnode contains new
> > "function" and "color" properties, or the legacy "label" proeprty.
> >
> > Backward compatibility with in-driver hard-coded LED class device
> > names is assured thanks to the default_label and led_hw_name properties
> > of newly introduced struct led_init_data.
> >
> > In case none of the aforementioned properties was found, then, for OF
> > nodes, the node name is adopted for LED class device name.
> >
> > At the occassion of amending the Documentation/leds/leds-class.txt
> > unify spelling: colour -> color.
> >
> > Alongside these changes added is a new tool - tools/leds/get_led_device_info.sh.
> > The tool allows retrieving details of a LED class device's parent device,
> > which proves that getting rid of a devicename section from LED name pattern
> > is justified since this information is already available in sysfs.
> >
> > Signed-off-by: Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx>
> > Cc: Baolin Wang <baolin.wang@xxxxxxxxxx>
> > Cc: Pavel Machek <pavel@xxxxxx>
> > Cc: Dan Murphy <dmurphy@xxxxxx>
> > Cc: Daniel Mack <daniel@xxxxxxxxxx>
> > Cc: Linus Walleij <linus.walleij@xxxxxxxxxx>
> > Cc: Oleh Kravchenko <oleg@xxxxxxxxxx>
> > Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > Cc: Simon Shields <simon@xxxxxxxxxxxxx>
> > ---
> >   Documentation/leds/leds-class.txt | 27 +++++++++--
> >   drivers/leds/led-class.c          | 29 ++++++++++--
> >   drivers/leds/led-core.c           | 96 +++++++++++++++++++++++++++++++++++++++
> >   include/linux/leds.h              | 43 ++++++++++++++++++
> >   tools/leds/get_led_device_info.sh | 81 +++++++++++++++++++++++++++++++++
> >   5 files changed, 270 insertions(+), 6 deletions(-)
> >   create mode 100755 tools/leds/get_led_device_info.sh
> >
> > diff --git a/Documentation/leds/leds-class.txt b/Documentation/leds/leds-class.txt
> > index 8b39cc6b03ee..11e19c3c2e4d 100644
> > --- a/Documentation/leds/leds-class.txt
> > +++ b/Documentation/leds/leds-class.txt
> > @@ -43,14 +43,35 @@ LED Device Naming
> >   
> >   Is currently of the form:
> >   
> > -"devicename:colour:function"
> > -
> > -There have been calls for LED properties such as colour to be exported as
> > +"color:function"
> > +
> > +There might be still LED class drivers around using "devicename:color:function"
> > +naming pattern, but the "devicename" section is now deprecated since it used
> > +to convey information that was already available in the sysfs, like product
> > +name. There is a tool (tools/leds/get_led_device_info.sh) available for
> > +retrieving that information per a LED class device.
> > +
> > +Associations with other devices, like network ones, should be defined
> > +via LED trigger mechanism. This approach is applied by some of wireless
> > +network drivers that create triggers dynamically and incorporate phy
> > +name into the trigger name. On the other hand input subsystem offers LED - input
> > +bridge (drivers/input/input-leds.c) for exposing keyboard LEDs as LED class
> > +devices. The get_led_device_info.sh script has support for retrieving related
> > +input device node name. Should it support discovery of associations between
> > +LEDs and other subsystems, please don't hesitate to submit a relevant patch.
> > +
> > +There have been calls for LED properties such as color to be exported as
> >   individual led class attributes. As a solution which doesn't incur as much
> >   overhead, I suggest these become part of the device name. The naming scheme
> >   above leaves scope for further attributes should they be needed. If sections
> >   of the name don't apply, just leave that section blank.
> >   
> > +Please also keep in mind that LED subsystem has a protection against LED name
> > +conflict. It adds numerical suffix (e.g. "_1", "_2", "_3" etc.) to the requested
> > +LED class device name in case it is already in use. In order to prevent LED core
> > +from assigning these suffixes in an arbitrary order the led-enumerator fwnode
> > +property can be used for differentiation of LEDs that share common function
> > +and/or color. In this case enumerators will be prepended with "-" character.
> >   
> >   Brightness setting API
> >   ======================
> > diff --git a/drivers/leds/led-class.c b/drivers/leds/led-class.c
> > index 2f09156b0c63..bfd46a9bba63 100644
> > --- a/drivers/leds/led-class.c
> > +++ b/drivers/leds/led-class.c
> > @@ -26,6 +26,18 @@
> >   
> >   static struct class *leds_class;
> >   
> > +const char *led_colors[LED_COLOR_ID_COUNT] = {
> > +	[LED_COLOR_ID_WHITE] = "white",
> > +	[LED_COLOR_ID_RED] = "red",
> > +	[LED_COLOR_ID_GREEN] = "green",
> > +	[LED_COLOR_ID_BLUE] = "blue",
> > +	[LED_COLOR_ID_AMBER] = "amber",
> > +	[LED_COLOR_ID_VIOLET] = "violet",
> > +	[LED_COLOR_ID_YELLOW] = "yellow",
> > +	[LED_COLOR_ID_IR] = "ir",
> > +};
> > +EXPORT_SYMBOL_GPL(led_colors);
> > +
>
> Why is this exported when it is only used here?
>
> I can re-use this array for the multi color framework so I don't oppose it being exported.

I did that specifically for that purpose :-)

> Reviewed-by: Dan Murphy <dmurphy@xxxxxx>

Thanks!

--
Best regards,
Jacek Anaszewski