On Fri, Nov 12, 2010 at 8:18 AM, Jimmy RUBIN [off-list ref] 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@gmail.com]
Sent: den 10 november 2010 15:43
To: Jimmy RUBIN
Cc: linux-fbdev@vger.kernel.org; linux-arm-kernel@lists.infradead.org; linux-media@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 [off-list ref] wrote:

quoted

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

quoted

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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