Hi Javier,

On Tue, Feb 8, 2022 at 4:10 PM Javier Martinez Canillas
[off-list ref] wrote:

On 2/8/22 15:19, Geert Uytterhoeven wrote:

quoted

On Fri, Feb 4, 2022 at 2:43 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.

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

Findings:
  - Kernel size increased by 349 KiB,
  - The "Memory:" line reports 412 KiB less memory,
  - On top of that, "free" shows ca. 92 KiB more memory in use after
    bootup.
  - 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.

quoted

  - 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.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds