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

Hello Geert,

On 2/1/22 09:43, Geert Uytterhoeven wrote:

Hi Javier,

On Mon, Jan 31, 2022 at 9:12 PM Javier Martinez Canillas
[off-list ref] wrote:

quoted

This patch series adds a DRM driver for the Solomon OLED SSD1305, SSD1306,
SSD1307 and SSD1309 displays. It is a port of the ssd1307fb fbdev driver.

Thanks for your series!

I'll give it a try on an Adafruit FeatherWing 128x32 OLED, connected
to an OrangeCrab ECP5 FPGA board running a 64 MHz VexRiscv RISC-V
softcore.

Awesome! let me know if you have any issues. I keep an update-to-date version
at https://github.com/martinezjavier/linux/tree/ssd1307

quoted

Using the DRM fb emulation, all the tests from Geert Uytterhoeven's fbtest
(https://git.kernel.org/pub/scm/linux/kernel/git/geert/fbtest.git) passes:

     ./fbtest -f /dev/fb1
    Using drawops cfb32 (32 bpp packed pixels)
    Available visuals:
      Monochrome
      Grayscale 256
      Truecolor 8:8:8:0

Oh, fake 32-bpp truecolor ;-)

Yes :) that's what the repaper drivers does to have maximum compatibility
with existing user-space and I followed the same.
 

Does it run modetest, too?

It does, yes. And for example `modetest -M ssd1307` will print all the
info about encoders, connectors, CRTs, etc.
 

I'm trying to get modetest working on my atari DRM driver.
Comparing to the cirrus driver doesn't help much, as modetest doesn't
seem to work with the cirrus driver (modified to not do hardware
access, as I don't have cirrus hardware):

    # modetest -M cirrus -s 31:1024x768-60Hz
    setting mode 1024x768-60.00Hz on connectors 31, crtc 34
    failed to set gamma: Function not implemented

# modetest -M ssd1307 -c -s 31:128x64-0.12Hz
...
setting mode 128x64-0.12Hz on connectors 31, crtc 33
failed to set gamma: Function not implemented

this seems to be a bug in modetest. I found a patch posted some time ago
but never landed: https://www.spinics.net/lists/dri-devel/msg251356.html
 

Does there exist another simple test program for showing something
using the DRM API?

I tested with plymouth and gdm that make use of the DRM API, they do
start and I see something on the screen but don't really handle that
well the fact that's a 128x64 resolution.

I didn't test with more DRM programs because was mostly interested in
making sure that the fbdev emulation was working correctly.

Noticed that Simon shared some simple examples, I'll give them a try. 

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