* Tony Lindgren <tony@xxxxxxxxxxx> [190403 13:06]: > * Sebastian Reichel <sre@xxxxxxxxxx> [190329 05:36]: > > Hi, > > > > On Mon, Mar 25, 2019 at 11:01:18AM -0500, Dan Murphy wrote: > > > On 3/25/19 9:54 AM, Tony Lindgren wrote: > > > > * Dan Murphy <dmurphy@xxxxxx> [190325 12:36]: > > > >> On 3/22/19 5:16 PM, Tony Lindgren wrote: > > > >>> I can control the backlight brightness just fine via /sys, and > > > >>> backlight shows up as the trigger in /sys/class/leds/lm3532:backlight, > > > >>> but /sys/class/backlight is empty and looks like drm can't find it. > > > >>> > > > >>> Do I need to enable some additional driver(s) to get this to work > > > >>> with the drm driver? > > > >>> > > > >> > > > >> Can you dump or point to the defconfig? > > > > > > > > This is just with the omap2plus_defconfig as in the droid4-pending-v5.0 > > > > test branch below [0]. That branch has Sebastian's drm patches. The > > > > branch also has the older ti-lmu patches that I reverted for testing > > > > before applying your new series and enabling it in .config. > > > > > > > > The drm driver (drivers/gpu/drm/omapdrm/displays/panel-dsi-cm.c) just > > > > does: > > > > > > > > backlight = of_parse_phandle(node, "backlight", 0); > > > > ... > > > > > > > > That should still work the same, right? > > > > > > Yes it should still work the same. > > > I did not change the node name. > > > So the DRM driver should find the node. > > > > This will not work, since the next line tries to get it as a > > backlight device, but it's an LED device instead: > > > > of_find_backlight_by_node(backlight); > > > > I suppose the backlight device could be instantiated on top > > of the LED device somehow. > > Hmm yeah I thought setting the ledtrig-backlight for it > would do the trick. But after thinking about it there might > be some backlight lifecycle issues with that where everything > would need to be torn down for the panel to change the > backlight trigger. I think the panel driver(s) assume the > backlight to always be there at probe time. Well this is > just based on just guessing.. I might be wrong. > > I have no issues using of_find_backlight_by_node() like > other panels. Oh sorry, I did not read the code before replying. I somehow thought of_find_backlight_by_node() should be used for LEDs but that's for backlight still :) Looks like all we need to do is leave out the backlight line from dts, we don't need to do anything with of_find_backlight_by_node(). Having ledtrig-backlight configured means lm3532 will just use the notifier for FB_EVENT_BLANK. I'll reply to the dts patch and ack the test, looks like we're good to go as far as I'm concerned. Regards, Tony
