On Wed, Aug 02, 2017 at 11:05:58AM -0500, David Lechner wrote: > On 08/02/2017 03:05 AM, Noralf Trønnes wrote: > > > > Den 02.08.2017 00.26, skrev David Lechner: > > > On 08/01/2017 01:08 PM, Noralf Trønnes wrote: > > > > (cc: Daniel Vetter) > > > > > > > > > > > > Den 01.08.2017 18.51, skrev David Lechner: > > > > > On 07/30/2017 12:14 PM, Noralf Trønnes wrote: > > > > > > > > > > > > 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. > > > > > > > > > > I don't expect many people to use it at all. The people that > > > > > do will be hackers like me that want to see what it is > > > > > capable of, so I think I will keep it grayscale by default. > > > > > > > > > > > > > It looks like the best way to satisfy your needs is to add > > > > specific formats. > > > > > > > > Video for Linux have these: > > > > > > > > include/uapi/linux/videodev2.h > > > > > > > > /* Grey formats */ > > > > #define V4L2_PIX_FMT_GREY v4l2_fourcc('G', 'R', 'E', 'Y') /* > > > > 8 Greyscale */ > > > > #define V4L2_PIX_FMT_Y4 v4l2_fourcc('Y', '0', '4', ' ') /* > > > > 4 Greyscale */ > > > > #define V4L2_PIX_FMT_Y6 v4l2_fourcc('Y', '0', '6', ' ') /* > > > > 6 Greyscale */ > > > > #define V4L2_PIX_FMT_Y10 v4l2_fourcc('Y', '1', '0', ' ') /* > > > > 10 Greyscale */ > > > > #define V4L2_PIX_FMT_Y12 v4l2_fourcc('Y', '1', '2', ' ') /* > > > > 12 Greyscale */ > > > > #define V4L2_PIX_FMT_Y16 v4l2_fourcc('Y', '1', '6', ' ') /* > > > > 16 Greyscale */ > > > > #define V4L2_PIX_FMT_Y16_BE v4l2_fourcc_be('Y', '1', '6', ' ') > > > > /* 16 Greyscale BE */ > > > > > > > > > > > > Maybe we can add formats like these: > > > > > > > > include/uapi/drm/drm_fourcc.h > > > > > > > > #define DRM_FORMAT_MONO fourcc_code('Y', '0', '1', ' ') > > > > /* [0] Monochrome */ > > > > or > > > > #define DRM_FORMAT_Y1 fourcc_code('Y', '0', '1', ' ') /* > > > > [0] Monochrome */ > > > > > > > > #define DRM_FORMAT_Y2 fourcc_code('Y', '0', '2', ' ') /* > > > > [1:0] Greyscale */ > > > > > > > > Daniel, what do you think? > > > > > > 2 of the first 3 tinydrm drivers are monochrome (and I would like to > > > write a driver for the Seeed/Grove I2C OLED displays which are also > > > monochrome), so I think the 1bpp modes would definitely be useful. I > > > think there is enough userspace code still around that knows about > > > FB_VISUAL_MONO01 and FB_VISUAL_MONO10 that could use these. > > > > > > > Can you elaborate, would you use the display trough monochrome fbdev > > or through drm? > > I have a small collection of programs and libraries that work using > monochrome fbdev. I would like to just keep using them without having to > convert everything to drm. That probably means we'd need to extend fbdev emulation helpers in drm to support Monochrome modes better. Shouldn't be that much work really. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
