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[2001:1c00:2a07:3a01:67e5:daf9:cec0:df6]) by smtp.gmail.com with ESMTPSA id 27-20020a170906301b00b00782539a02absm1033118ejz.194.2022.12.16.08.52.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 16 Dec 2022 08:52:46 -0800 (PST) Message-ID: Date: Fri, 16 Dec 2022 17:52:45 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 Subject: Re: [PATCH v3 06/11] v4l: subdev: Make the v4l2-subdev core code enable/disable the privacy LED if present Content-Language: en-US To: Laurent Pinchart Cc: Mark Gross , Andy Shevchenko , Pavel Machek , Lee Jones , Linus Walleij , Daniel Scally , Mauro Carvalho Chehab , Sakari Ailus , platform-driver-x86@vger.kernel.org, linux-leds@vger.kernel.org, linux-gpio@vger.kernel.org, Kate Hsuan , Mark Pearson , Andy Yeh , Yao Hao , linux-media@vger.kernel.org References: <20221216113013.126881-1-hdegoede@redhat.com> <20221216113013.126881-7-hdegoede@redhat.com> From: Hans de Goede In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org Hi, On 12/16/22 17:44, Laurent Pinchart wrote: > Hi Hans, > > On Fri, Dec 16, 2022 at 04:45:29PM +0100, Hans de Goede wrote: >> On 12/16/22 14:56, Laurent Pinchart wrote: >>> On Fri, Dec 16, 2022 at 12:30:08PM +0100, Hans de Goede wrote: >>>> Extend the call_s_stream() wrapper to enable/disable sensor privacy LEDs >>>> for sensors with a privacy LED, rather then having to duplicate this code >>>> in all the sensor drivers. >>>> >>>> Suggested-by: Sakari Ailus >>>> Signed-off-by: Hans de Goede >>>> --- >>>> drivers/media/v4l2-core/v4l2-subdev.c | 40 +++++++++++++++++++++++++++ >>>> include/media/v4l2-subdev.h | 3 ++ >>>> 2 files changed, 43 insertions(+) >>>> >>>> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c >>>> index 4988a25bd8f4..7344f6cd58b7 100644 >>>> --- a/drivers/media/v4l2-core/v4l2-subdev.c >>>> +++ b/drivers/media/v4l2-core/v4l2-subdev.c >>>> @@ -318,10 +318,44 @@ static int call_get_mbus_config(struct v4l2_subdev *sd, unsigned int pad, >>>> sd->ops->pad->get_mbus_config(sd, pad, config); >>>> } >>>> >>>> +#if IS_REACHABLE(CONFIG_LEDS_CLASS) >>>> +#include >>> >>> Can this be moved to the top of the file ? It doesn't have to be >>> conditionally compiled there. >> >> You mean just the #include right? Ack to that. > > Yes, that's what I meant. > >>>> + >>>> +static void call_s_stream_update_pled(struct v4l2_subdev *sd, int enable) >>>> +{ >>>> + if (!sd->dev) >>>> + return; >>>> + >>>> + /* Try to get privacy-led once, at first s_stream() */ >>>> + if (!sd->privacy_led) >>>> + sd->privacy_led = led_get(sd->dev, "privacy-led"); >>> >>> I'm not sure I like this much. If the LED provider isn't available >>> (yet), the LED will stay off. That's a privacy concern. >> >> At first I tried to put the led_get() inside v4l2_async_register_subdev_sensor(), >> which could then return an error like -EPROBE_DEFER if the led_get() >> fails (and nicely limits the led_get() to sensors). >> >> The problem which I hit is that v4l2-fwnode.c is build according to >> CONFIG_V4L2_FWNODE where as v4l2-subdev.c is build according to >> CONFIG_VIDEO_DEV >> >> And e.g. CONFIG_VIDEO_DEV could be builtin while CONFIG_V4L2_FWNODE >> could be a module and then having the #if IS_REACHABLE(CONFIG_LEDS_CLASS) >> spread over the 2 could result in different answers in the different >> files ... >> >> One solution here could be to change CONFIG_V4L2_FWNODE and V4L2_ASYNC >> to bools and link the (quite small) objects for these 2 into videodev.ko: >> >> videodev-$(CONFIG_V4L2_FWNODE) += v4l2-fwnode.o >> videodev-$(CONFIG_V4L2_ASYNC) += v4l2-async.o > > There's a long overdue simplification of Kconfig symbols in the > subsystem. Another option would be to compile both in a single module, > as they're often used together. I'll let Sakari chime in, I don't have a > strong preference. > >>>> + >>>> + if (IS_ERR(sd->privacy_led)) >>>> + return; >>>> + >>>> + mutex_lock(&sd->privacy_led->led_access); >>>> + >>>> + if (enable) { >>>> + led_sysfs_disable(sd->privacy_led); >>>> + led_trigger_remove(sd->privacy_led); >>>> + led_set_brightness(sd->privacy_led, sd->privacy_led->max_brightness); >>>> + } else { >>>> + led_set_brightness(sd->privacy_led, 0); >>>> + led_sysfs_enable(sd->privacy_led); >>> >>> I don't think you should reenable control through sysfs here. I don't >>> really see a use case, and you've removed the trigger anyway, so the >>> behaviour would be quite inconsistent. >> >> Hmm, I thought this was a good compromise, this way the LED >> can be used for other purposes when the sensor is off if users >> want to. >> >> Right if users want to use a trigger then they would need >> to re-attach the trigger after using the camera. >> >> But this way at least they can use the LED for other purposes >> which since many users don't use their webcam that often >> might be interesting for some users ... > > If the privacy LED starts being used for other purposes, users may get > used to seeing it on at random times, which defeats the point of the > privacy LED in the first place. Using it for other purposes it not something which I expect e.g. distros to do OOTB, so normal users won't see the LED used in another way. But it may be useful for tinkerers who do this as a local modification, in which case they know the LED behavior. With that said I'm fine with just disabling the sysfs interface once at probe / register time. Regards, Hans > >> And this is consistent with how flash LEDs are handled. >> >>> Also, I think it would be better if the LED device was marked as "no >>> sysfs" when it is registered. >> >> If we decide to permanently disallow userspace access then >> yes this is an option. Or maybe better (to keep the LED >> drivers generic), do the disable directly after the led_get() ? > > I suppose the small race condition wouldn't be a big issue, but if we > decide that the privacy LED should really not be used for user purposes, > then I'd still rather disable userspace access when registering the LED. > >>>> + } >>>> + >>>> + mutex_unlock(&sd->privacy_led->led_access); >>>> +} >>>> +#else >>>> +static void call_s_stream_update_pled(struct v4l2_subdev *sd, int enable) {} >>>> +#endif >>>> + >>>> static int call_s_stream(struct v4l2_subdev *sd, int enable) >>>> { >>>> int ret; >>>> >>>> + call_s_stream_update_pled(sd, enable); >>>> + >>>> ret = sd->ops->video->s_stream(sd, enable); >>>> >>>> if (!enable && ret < 0) { >>> >>> You need to turn the LED off when enabling if .s_stream() fails. >> >> Ack. >