linux-kernel - Re: [PATCH v2 0/2] drm: Add support for tiny LCD displays

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Message-ID: <20170130084424.wxdny2pzfmypvd4u@phenom.ffwll.local>
Date:   Mon, 30 Jan 2017 09:44:24 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     Noralf Trønnes <noralf@...nnes.org>
Cc:     dri-devel@...ts.freedesktop.org,
        thomas.petazzoni@...e-electrons.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 0/2] drm: Add support for tiny LCD displays

Hi Noralf,

On Fri, Jan 27, 2017 at 08:56:29PM +0100, Noralf Trønnes wrote:
> This is an attempt at providing a DRM version of drivers/staging/fbtft.
> 
> The tinydrm library provides a very simplified view of DRM in particular
> for tiny displays that has onboard video memory and is connected through
> a slow bus like SPI/I2C.
> 
> Only core patches this time.
> 
> 
> Noralf.
> 
> 
> Changes since version 1:
> - Add tinydrm.rst
> - Set tdev->fbdev_cma=NULL on unregister (lastclose is called after that).

Hm, this sounds like a buglet in the drm framework ... how do we call
lastclose when the driver is disappearing? I do see a drm_lastclose call
at the beginning of drm_dev_unregister (which we might want to remove for
KMS drivers, it doesn't make much sense imo), but that shouldn't result in
troubles.

> - Remove some DRM_DEBUG*()
> - Write-combined memory has uncached reads, so speed up by copying/buffering
>   one pixel line before conversion.

Hm, why are you using write-combining memory? Or is that needed so that
you can (if available) use hw spi engines?

Either way, I think this all looks good, pls submit a pull request to Dave
with these two patches as soon as latest drm-misc has landed (I'll send a
pull request for that later today).

Another one: Do you want to maintain tinydrm as part of the drm-misc
group, i.e. want commit rights there? That would also help a bit with
pushing all your great drm refactoring patches through the machinery ...

Cheers, Daniel

> 
> 
> Noralf Trønnes (2):
>   drm: Add DRM support for tiny LCD displays
>   drm/tinydrm: Add helper functions
> 
>  Documentation/gpu/index.rst                    |   1 +
>  Documentation/gpu/tinydrm.rst                  |  30 ++
>  drivers/gpu/drm/Kconfig                        |   2 +
>  drivers/gpu/drm/Makefile                       |   1 +
>  drivers/gpu/drm/tinydrm/Kconfig                |   8 +
>  drivers/gpu/drm/tinydrm/Makefile               |   1 +
>  drivers/gpu/drm/tinydrm/core/Makefile          |   3 +
>  drivers/gpu/drm/tinydrm/core/tinydrm-core.c    | 377 ++++++++++++++++++++
>  drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c | 462 +++++++++++++++++++++++++
>  drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c    | 234 +++++++++++++
>  include/drm/tinydrm/tinydrm-helpers.h          | 100 ++++++
>  include/drm/tinydrm/tinydrm.h                  | 115 ++++++
>  12 files changed, 1334 insertions(+)
>  create mode 100644 Documentation/gpu/tinydrm.rst
>  create mode 100644 drivers/gpu/drm/tinydrm/Kconfig
>  create mode 100644 drivers/gpu/drm/tinydrm/Makefile
>  create mode 100644 drivers/gpu/drm/tinydrm/core/Makefile
>  create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-core.c
>  create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
>  create mode 100644 drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
>  create mode 100644 include/drm/tinydrm/tinydrm-helpers.h
>  create mode 100644 include/drm/tinydrm/tinydrm.h
> 
> --
> 2.10.2
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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