[PATCH 00/10] MCDE: Add frame buffer device driver

[Alex Deucher]

On Fri, Nov 12, 2010 at 8:18 AM, Jimmy RUBIN <jimmy.rubin at stericsson.com> wrote:
> Hi Alex,
>
> Good point, we are looking at this for possible future improvements but for the moment we feel like
> the structure of drm does not add any simplifications for our driver. We have the display manager (MCDE DSS = KMS) and the memory manager (HWMEM = GEM) that could be migrated to drm framework. But we do not have drm drivers for 3D hw and this also makes drm a less obvious choice at the moment.
>

You don't have to use the drm strictly for 3D hardware.  historically
that's why it was written, but with kms, it also provides an interface
for complex display systems.  fbdev doesn't really deal properly with
multiple display controllers or connectors that are dynamically
re-routeable at runtime.  I've seen a lot of gross hacks to fbdev to
support this kind of stuff in the past, so it'd be nice to use the
interface we now have for it if you need that functionality.
Additionally, you can use the shared memory manager to both the
display side and v4l side.  While the current drm drivers use GEM
externally, there's no requirement that a kms driver has to use GEM.
radeon and nouveau use ttm internally for example.  Something to
consider.  I just want to make sure people are aware of the interface
and what it's capable of.

Alex

> Jimmy
>
> -----Original Message-----
> From: Alex Deucher [mailto:alexdeucher at gmail.com]
> Sent: den 10 november 2010 15:43
> To: Jimmy RUBIN
> Cc: linux-fbdev at vger.kernel.org; linux-arm-kernel at lists.infradead.org; linux-media at vger.kernel.org; Linus WALLEIJ; Dan JOHANSSON
> Subject: Re: [PATCH 00/10] MCDE: Add frame buffer device driver
>
> On Wed, Nov 10, 2010 at 7:04 AM, Jimmy Rubin <jimmy.rubin at stericsson.com> wrote:
>> These set of patches contains a display sub system framework (DSS) which is used to
>> implement the frame buffer device interface and a display device
>> framework that is used to add support for different type of displays
>> such as LCD, HDMI and so on.
>
> For complex display hardware, you may want to consider using the drm
> kms infrastructure rather than the kernel fb interface.  It provides
> an API for complex display hardware (multiple encoders, display
> controllers, etc.) and also provides a legacy kernel fb interface for
> compatibility.  See:
> Documentation/DocBook/drm.tmpl
> drivers/gpu/drm/
> in the kernel tree.
>
> Alex
>
>>
>> The current implementation supports DSI command mode displays.
>>
>> Below is a short summary of the files in this patchset:
>>
>> mcde_fb.c
>> Implements the frame buffer device driver.
>>
>> mcde_dss.c
>> Contains the implementation of the display sub system framework (DSS).
>> This API is used by the frame buffer device driver.
>>
>> mcde_display.c
>> Contains default implementations of the functions in the display driver
>> API. A display driver may override the necessary functions to function
>> properly. A simple display driver is implemented in display-generic_dsi.c.
>>
>> display-generic_dsi.c
>> Sample driver for a DSI command mode display.
>>
>> mcde_bus.c
>> Implementation of the display bus. A display device is probed when both
>> the display driver and display configuration have been registered with
>> the display bus.
>>
>> mcde_hw.c
>> Hardware abstraction layer of MCDE. All code that communicates directly
>> with the hardware resides in this file.
>>
>> board-mop500-mcde.c
>> The configuration of the display and the frame buffer device is handled
>> in this file
>>
>> NOTE: These set of patches replaces the patches already sent out for review.
>>
>> RFC:[PATCH 1/2] Video: Add support for MCDE frame buffer driver
>> RFC:[PATCH 2/2] Ux500: Add support for MCDE frame buffer driver
>>
>> The old patchset was to large to be handled by the mailing lists.
>>
>> Jimmy Rubin (10):
>>  MCDE: Add hardware abstraction layer
>>  MCDE: Add configuration registers
>>  MCDE: Add pixel processing registers
>>  MCDE: Add formatter registers
>>  MCDE: Add dsi link registers
>>  MCDE: Add generic display
>>  MCDE: Add display subsystem framework
>>  MCDE: Add frame buffer device driver
>>  MCDE: Add build files and bus
>>  ux500: MCDE: Add platform specific data
>>
>>  arch/arm/mach-ux500/Kconfig                    |    8 +
>>  arch/arm/mach-ux500/Makefile                   |    1 +
>>  arch/arm/mach-ux500/board-mop500-mcde.c        |  209 ++
>>  arch/arm/mach-ux500/board-mop500-regulators.c  |   28 +
>>  arch/arm/mach-ux500/board-mop500.c             |    3 +
>>  arch/arm/mach-ux500/devices-db8500.c           |   68 +
>>  arch/arm/mach-ux500/include/mach/db8500-regs.h |    7 +
>>  arch/arm/mach-ux500/include/mach/devices.h     |    1 +
>>  arch/arm/mach-ux500/include/mach/prcmu-regs.h  |    1 +
>>  arch/arm/mach-ux500/include/mach/prcmu.h       |    3 +
>>  arch/arm/mach-ux500/prcmu.c                    |  129 ++
>>  drivers/video/Kconfig                          |    2 +
>>  drivers/video/Makefile                         |    1 +
>>  drivers/video/mcde/Kconfig                     |   39 +
>>  drivers/video/mcde/Makefile                    |   12 +
>>  drivers/video/mcde/display-generic_dsi.c       |  152 ++
>>  drivers/video/mcde/dsi_link_config.h           | 1486 ++++++++++++++
>>  drivers/video/mcde/mcde_bus.c                  |  259 +++
>>  drivers/video/mcde/mcde_config.h               | 2156 ++++++++++++++++++++
>>  drivers/video/mcde/mcde_display.c              |  427 ++++
>>  drivers/video/mcde/mcde_dss.c                  |  353 ++++
>>  drivers/video/mcde/mcde_fb.c                   |  697 +++++++
>>  drivers/video/mcde/mcde_formatter.h            |  782 ++++++++
>>  drivers/video/mcde/mcde_hw.c                   | 2528 ++++++++++++++++++++++++
>>  drivers/video/mcde/mcde_mod.c                  |   67 +
>>  drivers/video/mcde/mcde_pixelprocess.h         | 1137 +++++++++++
>>  include/video/mcde/mcde.h                      |  387 ++++
>>  include/video/mcde/mcde_display-generic_dsi.h  |   34 +
>>  include/video/mcde/mcde_display.h              |  139 ++
>>  include/video/mcde/mcde_dss.h                  |   78 +
>>  include/video/mcde/mcde_fb.h                   |   54 +
>>  31 files changed, 11248 insertions(+), 0 deletions(-)
>>  create mode 100644 arch/arm/mach-ux500/board-mop500-mcde.c
>>  create mode 100644 drivers/video/mcde/Kconfig
>>  create mode 100644 drivers/video/mcde/Makefile
>>  create mode 100644 drivers/video/mcde/display-generic_dsi.c
>>  create mode 100644 drivers/video/mcde/dsi_link_config.h
>>  create mode 100644 drivers/video/mcde/mcde_bus.c
>>  create mode 100644 drivers/video/mcde/mcde_config.h
>>  create mode 100644 drivers/video/mcde/mcde_display.c
>>  create mode 100644 drivers/video/mcde/mcde_dss.c
>>  create mode 100644 drivers/video/mcde/mcde_fb.c
>>  create mode 100644 drivers/video/mcde/mcde_formatter.h
>>  create mode 100644 drivers/video/mcde/mcde_hw.c
>>  create mode 100644 drivers/video/mcde/mcde_mod.c
>>  create mode 100644 drivers/video/mcde/mcde_pixelprocess.h
>>  create mode 100644 include/video/mcde/mcde.h
>>  create mode 100644 include/video/mcde/mcde_display-generic_dsi.h
>>  create mode 100644 include/video/mcde/mcde_display.h
>>  create mode 100644 include/video/mcde/mcde_dss.h
>>  create mode 100644 include/video/mcde/mcde_fb.h
>>
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>