[Gta04-owner] Display on Debian - Was: Debian Status

H. Nikolaus Schaller hns at goldelico.com
Sat Feb 18 18:14:01 CET 2017


> Am 18.02.2017 um 18:03 schrieb Josua Mayer <josua.mayer97 at gmail.com>:
> 
> Am 18.02.2017 um 17:55 schrieb Josua Mayer:
>> Am 18.02.2017 um 17:46 schrieb H. Nikolaus Schaller:
>> 
>>>> Am 18.02.2017 um 17:44 schrieb H. Nikolaus Schaller <hns at goldelico.com>
>>>> :
>>>> 
>>>> 
>>>>> Am 18.02.2017 um 17:41 schrieb Josua Mayer <josua.mayer97 at gmail.com>
>>>>> :
>>>>> 
>>>>> 
>>>>>>> Adding:
>>>>>>> - display stays black. Any ideas?
>>>>>>> 
>>>>>> Hm. This can be a lot of things. Maybe X11 config.
>>>>>> Do you see a /sys/class/backlight entry?
>>>>>> 
>>>>> No x11. This is a minimal cli-only system.
>>>>> /sys/class/backlight is as empty as can be.
>>>>> I found that there are only 2 display connector modules available:
>>>>> connector-analog-tv.ko, connector-hdmi.ko
>>>>> With only the former loaded.
>>>>> 
>>>> That is ok since the omap3 has no hdmi port.
>>>> The panel is a separate driver.
>>>> 
>>>> 
>>>>> menuconfig lists DPI, HDMI, SDI and DSI.
>>>>> Is this the key here?
>>>>> 
>>>>> And we are probably also missing the panel drivers.
>>>>> 
>>>> Hm. The display system should work upstream - but maybe
>>>> they are not configured?
>>>> 
>>>> Display backlight also needs some omap pwm driver so this
>>>> can be the reason why it does not show up in /sys/class/backlight.
>>>> 
>>> In http://download.goldelico.com/letux-kernel/letux-4.10-rc8/src/CONFIG
>>> 
>>> we have backlight/pwm related:
>>> 
>>> CONFIG_BACKLIGHT_CLASS_DEVICE=y
>>> CONFIG_BACKLIGHT_GENERIC=m
>>> 
>> Do you know if this one is necessary? Its description is quote short.

Unfortunately no. I would guess that CONFIG_BACKLIGHT_CLASS_DEVICE enables
the /sys/class/backlight device.

>> Just in case Debian maintainers want to know an expalantions for every
>> option I request enabling.
>> 
>>> CONFIG_BACKLIGHT_PWM=m
>>> CONFIG_PWM=y
>>> CONFIG_PWM_SYSFS=y
>>> CONFIG_PWM_OMAP_DMTIMER=m
>>> 
>>> And for panel:
>>> 
>>> CONFIG_DRM_OMAP_PANEL_TPO_TD028TTEC1=m
>>> 
>> From those, missing are:
>> BACKLIGHT_GENERIC
>> DRM_OMAP_PANEL_TPO_TD028TTEC1
>> PWM_OMAP_DMTIMER
>> I am enabling them, and rebuilding this huge allmodconfig to test later.
>> 
> I found that replicant has
> CONFIG_FB_OMAP2_PANEL_TPO_TD028TTEC1

Well, there is some confusion in the display system. In fact the panel
drivers are duplicated.

Once for DRM (which I use since Debian Jessie) and the old FBDEV driver.

This had some problems with X11 but might work better for FB based
GUI systems like Replicant.

BR,
Nikolaus


> But you don't. So I will try without it first.
> (http://git.goldelico.com/?p=gta04-replicant-device.git;a=blob;f=rootdir/load_modules.sh;h=6ba0f4ef28af77108dff8064a5becf8f7b69d5f8;hb=refs/heads/next -  modprobe panel_tpo_td028ttec1 #Letux 2804)
>>> BR,
>>> Nikolaus
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> 
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