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

From: Daniel Vetter
Date: Mon Jan 30 2017 - 03:53:24 EST


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