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Date: Tue, 8 Feb 2022 16:10:49 +0100 From: Javier Martinez Canillas <javierm@...hat.com> To: Geert Uytterhoeven <geert@...ux-m68k.org> Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" <devicetree@...r.kernel.org>, Linux Fbdev development list <linux-fbdev@...r.kernel.org>, Linux PWM List <linux-pwm@...r.kernel.org>, David Airlie <airlied@...ux.ie>, Daniel Vetter <daniel.vetter@...ll.ch>, Mark Brown <broonie@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, DRI Development <dri-devel@...ts.freedesktop.org>, Liam Girdwood <lgirdwood@...il.com>, Rob Herring <robh+dt@...nel.org>, Noralf Trønnes <noralf@...nnes.org>, Thierry Reding <thierry.reding@...il.com>, Maxime Ripard <maxime@...no.tech>, Thomas Zimmermann <tzimmermann@...e.de>, Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, Lee Jones <lee.jones@...aro.org>, Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Sam Ravnborg <sam@...nborg.org> Subject: Re: [PATCH v2 0/4] drm/tiny: Add driver for Solomon SSD1307 OLED displays Hello Geert, Thanks a lot for testing! On 2/8/22 15:19, Geert Uytterhoeven wrote: > Hi Javier, > > On Fri, Feb 4, 2022 at 2:43 PM Javier Martinez Canillas > <javierm@...hat.com> wrote: >> 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 > - 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. > - "time ls" on the serial console (no files in the current directory, > so nothing to print) increases from 0.86s to 1.92s, so the system is > more loaded. As ssd1307fb relied on deferred I/O too, the slowdown > might be (partly) due to redrawing of the visual artefacts > mentioned above. > I was trying to first have the driver and then figure out how to optimize it. For v3 I'm using regmap to access instead of the I2C layer directly. I noticed that this is even slower but it makes the driver more clean and allows to support both I2C and SPI (untested but will include it as a WIP). > So while the displays seems to be initialized correctly, it looks like > there are some serious bugs in the conversion from xrgb8888 to > monochrome. > Yes, that's possible. I haven't tried to use it as a console before because the display resolution is just too small. But will include now in my tests. > Gr{oetje,eeting}s, > Best regards, -- Javier Martinez Canillas Linux Engineering Red Hat
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