From: Luca Weiss <luca@z3ntu.xyz>
To: linux-leds@vger.kernel.org,
Jacek Anaszewski <jacek.anaszewski@gmail.com>
Cc: ~postmarketos/upstreaming@lists.sr.ht,
Pavel Machek <pavel@ucw.cz>, Dan Murphy <dmurphy@ti.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] leds: add sgm3140 driver
Date: Sun, 08 Mar 2020 17:55:00 +0100 [thread overview]
Message-ID: <1832610.usQuhbGJ8B@g550jk> (raw)
In-Reply-To: <b58ddefc-b282-5a85-9dca-824e513705de@gmail.com>
Hi Jacek,
On Sonntag, 8. März 2020 17:47:17 CET Jacek Anaszewski wrote:
> Hi Luca,
>
> On 3/8/20 12:32 PM, Luca Weiss wrote:
> > Hi Jacek,
> >
> > Thanks for your review! Replies are inline below.
> >
> > I'm wondering if I should implement support for the flash-max-timeout-us
> > dt
> > property ("Maximum timeout in microseconds after which the flash LED is
> > turned off.") to configure the timeout to turn the flash off as I've
> > currently hardcoded 250ms but this might not be ideal for all uses of the
> > sgm3140. The datasheet>
> > states:
> >> Flash mode is usually used with a pulse of about 200 to 300 milliseconds
> >> to
> >> generate a high intensity Flash.
> >
> > so it might be useful to have this configurable in the devicetree. The
> > value of 250ms works fine for my use case.
>
> Yeah, I was to mentioned that.
>
> > Theoretically also the .timeout_set op could be implemented but I'm not
> > sure if this fits nicely into the existing "timeout" API and if it even
> > makes sense to implement that.
>
> Why wouldn't it fit? You can implement timeout_set op and cache flash
> timeout value in it. Then that cached value would be passed in
> strobe_set to mod_timer() in place of currently hard coded 250.
>
I'll implement that then.
> > Regards,
> > Luca
> >
> > On Donnerstag, 5. März 2020 22:09:16 CET Jacek Anaszewski wrote:
> >> Hi Luca,
> >>
> >> Thank you for the patch.
> >>
> >> On 2/27/20 7:50 PM, Luca Weiss wrote:
> >>> Add a driver for the SGMICRO SGM3140 Buck/Boost Charge Pump LED driver.
> >>>
> >>> This device is controller by two GPIO lines, one for enabling the LED
> >>> and the second one for switching between torch and flash mode.
> >>>
> >>> The device will automatically switch to torch mode after being in flash
> >>> mode for about 250-300ms, so after that time the driver will turn the
> >>> LED off again automatically.
> >>>
> >>> Signed-off-by: Luca Weiss <luca@z3ntu.xyz>
> >>> ---
> >>> Hi, this driver is controllable via sysfs and v4l2 APIs (as documented
> >>> in Documentation/leds/leds-class-flash.rst).
> >>>
> >>> The following is possible:
> >>>
> >>> # Torch on
> >>> echo 1 > /sys/class/leds/white\:flash/brightness
> >>> # Torch off
> >>> echo 0 > /sys/class/leds/white\:flash/brightness
> >>> # Activate flash
> >>> echo 1 > /sys/class/leds/white\:flash/flash_strobe
> >>>
> >>> # Torch on
> >>> v4l2-ctl -d /dev/video1 -c led_mode=2
> >>> # Torch off
> >>> v4l2-ctl -d /dev/video1 -c led_mode=0
> >>> # Activate flash
> >>> v4l2-ctl -d /dev/video1 -c strobe=1
> >>
> >> What is /dev/video1 ? Did you register vl42 flash subdev
> >> in some v4l2 media controller device?
> >
> > On the Allwinner A64 SoC /dev/video0 is the node for cedrus (video
> > encoder/
> > decoder), so the sun6i-csi driver gets to be /dev/video1
> >
> > # v4l2-ctl --list-devices
> >
> > cedrus (platform:cedrus):
> > /dev/video0
> > /dev/media0
> >
> > sun6i-csi (platform:csi):
> > /dev/video1
> >
> > Allwinner Video Capture Device (platform:sun6i-csi):
> > /dev/media1
> >
> > Here's the relevant part from my dts:
> >
> > sgm3140 {
> >
> > compatible = "sgmicro,sgm3140";
> > flash-gpios = <&pio 3 24 GPIO_ACTIVE_HIGH>; /* FLASH_TRIGOUT: PD24 */
> > enable-gpios = <&pio 2 3 GPIO_ACTIVE_HIGH>; /* FLASH_EN: PC3 */
> >
> > sgm3140_flash: led {
> >
> > function = LED_FUNCTION_FLASH;
> > color = <LED_COLOR_ID_WHITE>;
> >
> > };
> >
> > };
>
> This needs to be documented in DT bindings for this driver.
>
I have already written some yesterday, will post them with my v1 :)
> > /* as subnode of csi (compatible: allwinner,sun50i-a64-csi) */
> > ov5640: rear-camera@4c {
> >
> > compatible = "ovti,ov5640";
> > <snip>
> > flash-leds = <&sgm3140_flash>;
> >
> > };
>
> And this in camera bindings.
This is documented at
Documentation/devicetree/bindings/media/video-interfaces.txt:
- flash-leds: An array of phandles, each referring to a flash LED, a sub-node
of the LED driver device node.
Without referencing the flash device in a camera node, the v4l2 controls won't
even show up from what I saw.
The binding is apparently only used in omap3-n9 and omap3-n950 currently; only
phones have flash leds normally and the phones that are currently in mainline
Linux don't have camera support yet.
Regards
Luca
next prev parent reply other threads:[~2020-03-08 16:55 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-27 18:50 [RFC PATCH] leds: add sgm3140 driver Luca Weiss
2020-02-27 19:50 ` Dan Murphy
2020-03-05 11:01 ` Luca Weiss
2020-03-05 12:54 ` Dan Murphy
2020-03-05 21:09 ` Jacek Anaszewski
2020-03-08 11:32 ` Luca Weiss
2020-03-08 16:47 ` Jacek Anaszewski
2020-03-08 16:55 ` Luca Weiss [this message]
2020-03-08 17:21 ` Jacek Anaszewski
2020-03-08 12:08 ` Pavel Machek
2020-03-08 12:31 ` Luca Weiss
2020-03-08 17:07 ` Jacek Anaszewski
2020-03-08 12:11 ` Pavel Machek
2020-03-08 12:37 ` Luca Weiss
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1832610.usQuhbGJ8B@g550jk \
--to=luca@z3ntu.xyz \
--cc=dmurphy@ti.com \
--cc=jacek.anaszewski@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-leds@vger.kernel.org \
--cc=pavel@ucw.cz \
--cc=~postmarketos/upstreaming@lists.sr.ht \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).