Re: [PATCH v3 2/2] drm/tiny: add support for PIXPAPER 4.26 monochrome e-ink panel

[Thomas Zimmermann]

(cc'ing Javier for ssd130x expertise)

Hi

Am 16.09.26 um 11:44 schrieb LiangCheng Wang:
> Hi Thomas,
>
> Thank you for the quick reply.
>
> > Where exactly are these ssd16xx patches. I cannot find them in the DRM
> > trees. I presume they are not upstream yet?
> That is right, they are not upstream. Devarsh posted them on 1 May and
> the series is still at v1 on the list:
>
>    [PATCH 0/6] Add DRM driver for Solomon SSD16xx e-paper display controllers
>    https://lore.kernel.org/all/20260430183311.2978142-1-devarsht@xxxxxx/
>
> One thing that is easy to miss, and that I should have made clearer in my
> last mail: that v1 series covers the SSD1683 only. The SSD1677, which is
> the controller on the PIXPAPER 4.26m, is not part of it. Devarsh has
> SSD1677 support in a staged branch that he kindly shared with me in July,
> and that is what I tested on the panel:
>
>    https://github.com/devarsht/linux-next/commits/ssd16xx_7_2/
>
> Those SSD1677 patches have not been posted to the list yet, which is why
> the panel support has not had anything to build on so far.
>
> > If there's support for similar ICs, I'd strongly prefer to have the
> > ssd1677 be part of that instead of a stand-alone driver.
> >
> > Once the stand-alone driver is in place, users will rely on it. Then it
> > becomes hard to replace. We had (have?) cases where there are several
> > drivers for the same hardware.
> Understood, and thank you for explaining the reasoning - the point about
> users coming to depend on a driver that is then hard to replace makes
> sense, and I would rather not create that problem. I will drop the
> standalone driver and add the PIXPAPER 4.26m to ssd16xx instead, once the
> shared driver is in.

Oh, I now took a closer look at the ssd16xx driver.  I thought that it 
would use the panel helpers, but that's not the case. It's a 'regular' 
DRM driver.

If the ssd16xx does not make progress, we could also try to merge your 
code as ssd16xx and Devarsh would then add support for additional ICs on 
top.

There's also the ssd130x driver under solomon/ how does it related to 
the ssd16xx? Is that similar as well?

Best regards
Thomas

> Devarsh, thank you again for sharing the branch, and for making room for
> the panel in your work in the first place. I am glad to keep testing
> SSD1677 on real hardware whenever that is useful to you.
>
> Regards,
> LiangCheng

--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstr. 146, 90461 Nürnberg, Germany, www.suse.com
GF: Jochen Jaser, Andrew McDonald, (HRB 36809, AG Nürnberg)