Messages in this thread | | | Subject | Re: [PATCH 0/6] Support for LEGO MINDSTORMS EV3 LCD display | From | Noralf Trønnes <> | Date | Sun, 30 Jul 2017 19:14:15 +0200 |
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Den 29.07.2017 21.40, skrev David Lechner: > On 07/29/2017 02:17 PM, David Lechner wrote: >> The goal of this series is to get the built-in LCD of the LEGO >> MINDSTORMS EV3 >> working. But, most of the content here is building up the >> infrastructure to do >> that. >> > > Some general comments/questions: > > I have noticed that DRM doesn't really have support for monochrome > displays. I'm guessing that is because no one really uses them anymore? >
The repaper driver was the first monochrome drm driver and I chose to present it to userspace as XRGB8888 and convert it to monochrome. The reason for this is that everything, libraries, apps, plymouth (boot splash, no rgb565) supports it. I didn't see any point in adding a new monochrome drm format that didn't have, or probably wouldn't get userspace support (by libraries at least). The application of course needs to know this to get a good result.
tinydrm_xrgb8888_to_gray8() does the conversion: https://cgit.freedesktop.org/drm/drm-misc/commit/drivers/gpu/drm/tinydrm?id=379ea9a1a59a5a32c8db6f164e80a3fd00cb3781
> The LEGO EV3 display is just an LCD (not the backlit kind). It has two > modes of operation. It can to 2bbp grayscale or it can do 1bpp > monochrome. The grayscale isn't the best (looks splotchy in places), > so it would be nice to be able to choose between these two modes. How > would I implement something like that? >
Do you expect anyone to use grayscale if it doesn't look good? Maybe better to add it later if there's a demand for it.
> Also, how can I indicate to userspace that this display really is > monochrome/grayscale since the reported color depth 16bpp? >
There isn't unless we add formats for it. Since this display is in a Lego piece, doesn't it have custom userspace that already know it's monochrome?
Noralf.
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