Re: [PATCH v2 0/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays

[Javier Martinez Canillas <javierm@redhat.com>]

On 2/8/22 16:23, Geert Uytterhoeven wrote:

[snip]

>>>   - The logo (I have a custom monochrome logo enabled) is no longer shown.
>>
>> I was able to display your tux monochrome with ./fbtest -f /dev/fb1 test004
> 
> I meant the kernel's logo (FB_LOGO_*),. Obviously you need to enable
> a smaller one, as the default 80x80 logo is too large, and thus can't
> be drawn on your 128x64 or my 128x32 display.
>

That makes sense.
 
>>>   - The screen is empty, with a (very very slow) flashing cursor in the
>>>     middle of the screen, with a bogus long line next to it, which I can
>>>     see being redrawn.
>>>   - Writing text (e.g. hello) to /dev/tty0, I first see the text,
>>>     followed by an enlargement of some of the characters.
>>
>> So far I was mostly testing using your fbtest repo tests and all of them
>> (modulo test009 that says "Screen size too small for this test").
>>
>> But I've tried now using as a VT and I see the same visual artifacts. I
>> wonder what's the difference between fbcon and the way your tests use
>> the fbdev API.
> 
> Fbcon does small writes to the shadow frame buffer, while fbtest
> writes to the mmap()ed /dev/fbX, causing a full page to be updated.
>

I see. Thanks for the information.

Best regards, -- 
Javier Martinez Canillas
Linux Engineering
Red Hat