[RFC 0/7] drm/omap: Module parameter for display order configuration

[Peter Ujfalusi <peter.ujfalusi@ti.com>]

Hi

The series adds support for changing the order of the displays defined by DT
display aliases.

The motivation to do such a thing is that for example the fb emulation is
treating the first display/crtc as the 'main' display and will create the
fb emulation based on the first display's properties.
There are many custom applications using DRM directly and they assume that the
first connector is the 'main' display.
Afaik weston provides no means either to change the 'main/preferred' display.

It should be the work of user space application (except the fb emulation) to
somehow deal with the 'main' display selection for their needs, but
unfortunately they are not capable of diong so for some reason.

We have boards with LCD panel and HDMI for example and in DT the LCD is set as
display0, but in certain useage scenarios it is desired to have the HDMI as the
'main' display instead of the LCD.

With the kernel cmd line parameter it is possible to change the pre defined
order without recompiling the kernel/DT.

If the board have two active displays:
0 - LCD
1 - HDMI
then:
omapdrm.displays=0,1 - represents the original order (LCD, HDMI)
omapdrm.displays=1,0 - represents reverse order (HDMI, LCD)
omapdrm.displays=0 - only the LCD is enabled
omapdrm.displays=1 - only the HDMI is enabled
omapdrm.displays=-1 - disable all displays

The first 6 patch of the series is doing some generic clean up and prepares the
code so the display ordering is going to be easy to add.

Regards,
Peter
---
Peter Ujfalusi (7):
  drm/omap: Use devm_kzalloc() to allocate omap_drm_private
  drm/omap: Allocate drm_device earlier and unref it as last step
  drm/omap: Manage the usable omap_dss_device list within
    omap_drm_private
  drm/omap: Separate the dssdevs array setup from the connect function
  drm/omap: Do dss_device (display) ordering in omap_drv.c
  drm/omap: dss: Remove display ordering from dss/display.c
  drm/omap: Add kernel parameter to specify the desired display order

 drivers/gpu/drm/omapdrm/dss/display.c |  15 +--
 drivers/gpu/drm/omapdrm/dss/omapdss.h |   3 -
 drivers/gpu/drm/omapdrm/omap_drv.c    | 244 ++++++++++++++++++++++++----------
 drivers/gpu/drm/omapdrm/omap_drv.h    |   3 +
 4 files changed, 183 insertions(+), 82 deletions(-)

-- 
2.14.1


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