[Letux-kernel] Kernel v5.1-rc1 (was: LetuxOS Kernel v5.0-rc1)

H. Nikolaus Schaller hns at goldelico.com
Wed Mar 20 16:31:59 CET 2019


Hi,

> Am 20.03.2019 um 08:30 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
> Hi,
> 
>> Am 20.03.2019 um 08:19 schrieb Andreas Kemnade <andreas at kemnade.info>:
>> 
>> Hi,
>> 
>> 
>> On Tue, 19 Mar 2019 13:30:17 +0100
>> "H. Nikolaus Schaller" <hns at goldelico.com> wrote:
>> 
>>>> Am 19.03.2019 um 13:16 schrieb H. Nikolaus Schaller <hns at goldelico.com>:
> 
>>>>>> * GTA04A4:	backlight ok, display shows white pixels only  
>>>>> 
>>>>> hmm, did a quick test with mainline: older dtb + 5.1-rc1 kernel = display ok
>>>>> 5.1-rc1 kernel + dtb-5-1-rc1 (both mainline) = black screen  
> 
> Ah, I didn't read precisely: "black screen". I get this as well if I eliminate
> most Letux patch sets.
> 
> This means that one or two hacks are not yet upstream...
> 
>>>> 
>> well,
>> echo 0 >/sys/class/backlight/backlight/bl_power
>> resolved that. Then I had a working display with mainline 5.1-rc1 + dtb-5.1-rc1
>> 
>> I think we are talking about different problems.
> 
> Looks so...
> 
> My main symptom is that I get a /dev/fb0, X server process is running, backlight
> is on, but the screen is completely white. And xset dpms force on/off can
> turn backlight on&off. But still only white pixels.
> 
> I guess the problem is either the SPI interface to the panel or the pixel
> clock/pixel data.
> 
> I am currently running a bisect to find out more.

First result:

	67e79a6dc2664a3ef85113440e60f7aaca3c7815 is the first bad commit

i.e.

	https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=67e79a6dc2664a3ef85113440e60f7aaca3c7815

But what does this have to do with the GTA04 display and backlight power???

I fear a side-effect of an array out of bounds write like we did have a while ago.

Or I did make a mistake in reporting good/bad to git bisect. Maybe I should repeat.

Note this is using mainline linux (bisected) + letux/compile-fixes + letux/arm_defconfig + letux/Letux + letux/ubi-fs and nothing else.
So it does not include many of the Letux hacks.

BR,
Nikolaus



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