From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jani Nikula Date: Wed, 31 Jan 2018 11:51:21 +0000 Subject: Re: [PATCH 1/5] backlight: lp8788: document sysfs attributes Message-Id: <878tceckli.fsf@intel.com> List-Id: References: <6523e26889d3dd65e90ea27c0d302a95aeb9da8b.1516978005.git.aishpant@gmail.com> <20180131110727.rmmwyqzwozwhda6z@oak.lan> In-Reply-To: <20180131110727.rmmwyqzwozwhda6z@oak.lan> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Daniel Thompson , Aishwarya Pant Cc: Milo Kim , linux-fbdev@vger.kernel.org, Jonathan Corbet , Jingoo Han , Bartlomiej Zolnierkiewicz , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Julia Lawall , Greg KH , Lee Jones On Wed, 31 Jan 2018, Daniel Thompson wrote: > On Fri, Jan 26, 2018 at 08:20:08PM +0530, Aishwarya Pant wrote: >> Add documentation for sysfs interfaces of lp8788 backlight driver by >> looking through the code and the git commit history. >> >> Signed-off-by: Aishwarya Pant >> --- >> Documentation/ABI/testing/sysfs-class-backlight-lp8788 | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> create mode 100644 Documentation/ABI/testing/sysfs-class-backlight-lp8788 >> >> diff --git a/Documentation/ABI/testing/sysfs-class-backlight-lp8788 b/Documentation/ABI/testing/sysfs-class-backlight-lp8788 >> new file mode 100644 >> index 000000000000..c0e565c8d63d >> --- /dev/null >> +++ b/Documentation/ABI/testing/sysfs-class-backlight-lp8788 >> @@ -0,0 +1,10 @@ >> +sysfs interface for Texas Instruments lp8788 mfd backlight driver >> +----------------------------------------------------------------- >> + >> +What: /sys/class/backlight//bl_ctl_mode >> +Date: Feb, 2013 >> +KernelVersion: v3.10 >> +Contact: Milo Kim >> +Description: >> + (RO) Displays whether the brightness is controlled by the PWM >> + input("PWM based") or the I2C register("Register based"). > > I rather dislike drivers with this type of "bonus" sysfs controls. I'm > struggling to come up with any reason why the userspace would want to > read this control (and I think bl_ctl_mode gets the fewest hits after > searching with google hits of any search I've tried) . It looks to me > like this is debug information that should never have gone into sysfs > at all. Agreed. I think the same holds for the other extra sysfs attributes. At worst, having these prevents the backlight class from adding the names later on, which is just backwards. BR, Jani. > > So I think this is either something that should go directly into > ABI/obsolete (with a fairly short expiry time) or perhaps simply > remove the property entirely. > > > Daniel. > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel -- Jani Nikula, Intel Open Source Technology Center