Re: [PATCH v6 3/6] drm: Add driver for Solomon SSD130x OLED displays

From: Javier Martinez Canillas <javierm@redhat.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"Linux Fbdev development list" <linux-fbdev@vger.kernel.org>,
	"Andy Shevchenko" <andriy.shevchenko@linux.intel.com>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Sam Ravnborg" <sam@ravnborg.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Maxime Ripard" <maxime@cerno.tech>,
	"Noralf Trønnes" <noralf@tronnes.org>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"David Airlie" <airlied@linux.ie>,
	"Lee Jones" <lee.jones@linaro.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	"Maxime Ripard" <mripard@kernel.org>,
	"Thierry Reding" <thierry.reding@gmail.com>,
	"Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	"Linux PWM List" <linux-pwm@vger.kernel.org>
Subject: Re: [PATCH v6 3/6] drm: Add driver for Solomon SSD130x OLED displays
Date: Wed, 9 Mar 2022 13:14:13 +0100	[thread overview]
Message-ID: <fd6ec463-f46d-0813-5d87-a00c07739e01@redhat.com> (raw)
In-Reply-To: <CAMuHMdU+29x4ZHLAiPiReyLKw_VYBCCLw0bCoQmw9s6sQ4Bxcw@mail.gmail.com>

On 3/8/22 17:30, Geert Uytterhoeven wrote:
> Hi Javier,
> 
> On Mon, Feb 14, 2022 at 2:37 PM Javier Martinez Canillas
> <javierm@redhat.com> wrote:
>> This adds a DRM driver for SSD1305, SSD1306, SSD1307 and SSD1309 Solomon
>> OLED display controllers.
>>
>> It's only the core part of the driver and a bus specific driver is needed
>> for each transport interface supported by the display controllers.
>>
>> Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
> 
> Thanks for your patch, which is now commit a61732e808672cfa ("drm:
> Add driver for Solomon SSD130x OLED displays") in drm/drm-next
> 
> Sorry for the delay, but finally I gave it a try on my Adafruit
> FeatherWing 128x32 OLED.
> Some of the weird issues (cursor disappears after printing some text,
> more text also doesn't appear until I clear the display) are still there.

I see. Thought that I tested using it as a console and it did work
correctly for me. I'll do more tests again.

> Unfortunately a regression was introduced since your v3: printed
> text is mirrored upside-down. I.e. "E" is rendered correctly, but "L"
> turns into "Γ" (Greek Gamma).
> I suspect something went wrong with the display initialization
> sequence.
>

Could you please try Chen-Yu's fix for the COM scan direction mask ?

https://lists.freedesktop.org/archives/dri-devel/2022-March/345915.html

I made a mistake when converting to use the GENMASK() and FIELD_PREP()
macros in v4 as suggested by Andy. The SSD130X_SET_COM_SCAN_DIR_MASK
wasn't correct which would explain the output to be vertically flipped.

-- 
Best regards,

Javier Martinez Canillas
Linux Engineering
Red Hat