Messages in this thread | | | Date | Mon, 31 Jan 2022 11:28:23 +0100 | Subject | Re: [PATCH v1 1/4] fbtft: Unorphan the driver | From | Thomas Zimmermann <> |
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Hi
Am 31.01.22 um 11:18 schrieb Javier Martinez Canillas: > Hello Thomas, > > On 1/31/22 10:18, Thomas Zimmermann wrote: > > [snip] > >>> There are some hacks in the driver though. For example it exposes an XRGB8888 >>> format even thought the OLED display is monochromatic and has 1 bit per pixel. >>> >>> The driver then goes and converts the XRGB8888 pixels first to grayscale and >>> then to reverse mono. I took that idea from the repaper driver but that gives >>> us the multiple copies that Geert was complaining about. >> >> This requires to update the console code for 1-bit BW output. The fbcon >> side already supports this AFAIK. DRM's fbdev needs a few more branches >> and something like a DRM_FORMAT_C1 fourcc. The XRGB8888 is really a >> userspace requirement that is imposed by modern desktops. If DRM's >> console has been updated, you could leave it out entirely. >> >> I could imagine that some simple userspace, such as Weston, comes with >> support for palette formats and BW. Or there could be an entirely >> separate program that puts graphics onto these displays. >> > > Yes, I understand the rationale of why the repaper driver is doing that way > but was just pointing out because Geert mentioned that is not efficient.
It's a fair point, I think. People are concerned about resource consumption on low-end devices.
> > Maybe in the meantime we can add a drm_fb_gray8_to_mono_reversed() helper to > drivers/gpu/drm/drm_format_helper.c since there is more than one driver that > does the same ?
Sure.
> > It's not a big issue for this device really since the I2C bus is slow anyways > and the multiple copies are not a bottleneck AFAICT. > > I believe is worth to propose this driver as is and then try to optimize later.
Absolutely. If you post a cleaned-up version of the patch, I'd take a look.
> > Another thing that's missing is a DRM_MODE_CONNECTOR_I2C, because I used for > now a DRM_MODE_CONNECTOR_Unknown.
That might have implications on userspace. Maybe ask around. (Not that we actually run userspace on the device).
Best regards Thomas
> > Best regards,
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Ivo Totev [unhandled content-type:application/pgp-signature] | |