[Letux-kernel] [PATCH 0/2] drm/omap: panel-tpo-td028ttec1: add backlight support

H. Nikolaus Schaller hns at goldelico.com
Sat Jan 19 20:39:39 CET 2019

Hi Andreas,
thank you very much for submitting these patches!

I always had wondered why screen blanking works on L3704 but
not on L2804/GTA04. The answer is because it uses the dpi driver
and not a dedicated one. But I never got to work on it.

Yes, the panel-boe-w677l.c also should have a similar thing.

The existing w677l_backlight_ops are remains from the original
driver which was forked from some driver that had backlight
support. But since then the API had changed significantly
so I removed most of the code, just leaving this as a "todo"

BR and thanks,

PS: at the moment I am struggling to restore my main computer since
it has a file system corruption beyond fsck(_hfs) capabilities...
Just a single problem but it prevents the FS from becoming clean
which stops the boot process.

Therefore I will need a little more time to make a snapshot of the
broken SSD (700 GB...) and restore from a backup before I can
continue work.

> Am 19.01.2019 um 20:15 schrieb Andreas Kemnade <andreas at kemnade.info>:
> Hi,
> I stumbled across this during the panel debugging in 4.20.
> We had it working in 3.7. But afaik not even in 3.12 anymore,
> Same thing might be interesting for other panels where we use
> pwm_bl.
> Probably the panel-boe-w677l.c could use something like this also.
> But why is there 
> static const struct backlight_ops w677l_backlight_ops
> = { .get_brightness = w677l_get_brightness,
> 	.update_status = w677l_set_brightness,
> };
> and it is never used.
> If this gets accepted, I will try to upstream dtb updates as well.
> Regards,
> Andreas
> On Sat, 19 Jan 2019 19:21:29 +0100
> Andreas Kemnade <andreas at kemnade.info> wrote:
>> This panel has a backlight, so add a property describing that and
>> add the code to use that.
>> This makes things like xset dpms force off
>> also turn off the backlight, so we do not need to rely on additional
>> userspace programs to do that.
>> Andreas Kemnade (2):
>>  drm/omap: panel-tpo-td028ttec1: add backlight support
>>  dt-bindings: panel: td028ttec1: add backlight property
>> .../bindings/display/panel/tpo,td028ttec1.txt          |  2 ++
>> .../gpu/drm/omapdrm/displays/panel-tpo-td028ttec1.c    | 18 +++++++++++++++---
>> 2 files changed, 17 insertions(+), 3 deletions(-)
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