Re: [PATCH 00/10] Improvements and fixes for mxsfb DRM driver

[Guido Günther]

Hi Robert,
On Wed, Jun 26, 2019 at 04:32:08PM +0300, Robert Chiras wrote:
> This patch-set improves the use of eLCDIF block on iMX 8 SoCs (like 8MQ, 8MM
> and 8QXP). Following, are the new features added and fixes from this
> patch-set:
> 
> 1. Add support for drm_bridge
> On 8MQ and 8MM, the LCDIF block is not directly connected to a parallel
> display connector, where an LCD panel can be attached, but instead it is
> connected to DSI controller. Since this DSI stands between the display
> controller (eLCDIF) and the physical connector, the DSI can be implemented
> as a DRM bridge. So, in order to be able to connect the mxsfb driver to
> the DSI driver, the support for a drm_bridge was needed in mxsfb DRM
> driver (the actual driver for the eLCDIF block).

So I wanted to test this but with both my somewhat cleaned up nwl
driver¹ and the nwl driver forward ported from the nxp vendor tree I'm
looking at a black screen with current mainline - while my dcss forward
port gives me nice output on mipi dsi. Do you have a tree that uses mipi
dsi on imx8mq where I could look at to check for differences?

Cheers,
 -- Guido

> 
> 2. Add support for additional pixel formats
> Some of the pixel formats needed by Android were not implemented in this
> driver, but they were actually supported. So, add support for them.
> 
> 3. Add support for horizontal stride
> Having support for horizontal stride allows the use of eLCDIF with a GPU
> (for example) that can only output resolution sizes multiple of a power of
> 8. For example, 1080 is not a power of 16, so in order to support 1920x1080
> output from GPUs that can produce linear buffers only in sizes multiple to 16,
> this feature is needed.
> 
> 3. Few minor features and bug-fixing
> The addition of max-res DT property was actually needed in order to limit
> the bandwidth usage of the eLCDIF block. This is need on systems where
> multiple display controllers are presend and the memory bandwidth is not
> enough to handle all of them at maximum capacity (like it is the case on
> 8MQ, where there are two display controllers: DCSS and eLCDIF).
> The rest of the patches are bug-fixes.
> 
> Mirela Rabulea (1):
>   drm/mxsfb: Signal mode changed when bpp changed
> 
> Robert Chiras (9):
>   drm/mxsfb: Update mxsfb to support a bridge
>   drm/mxsfb: Update mxsfb with additional pixel formats
>   drm/mxsfb: Fix the vblank events
>   dt-bindings: display: Add max-res property for mxsfb
>   drm/mxsfb: Add max-res property for MXSFB
>   drm/mxsfb: Update mxsfb to support LCD reset
>   drm/mxsfb: Improve the axi clock usage
>   drm/mxsfb: Clear OUTSTANDING_REQS bits
>   drm/mxsfb: Add support for horizontal stride
> 
>  .../devicetree/bindings/display/mxsfb.txt          |   6 +
>  drivers/gpu/drm/mxsfb/mxsfb_crtc.c                 | 290 ++++++++++++++++++---
>  drivers/gpu/drm/mxsfb/mxsfb_drv.c                  | 189 +++++++++++---
>  drivers/gpu/drm/mxsfb/mxsfb_drv.h                  |  10 +-
>  drivers/gpu/drm/mxsfb/mxsfb_out.c                  |  26 +-
>  drivers/gpu/drm/mxsfb/mxsfb_regs.h                 | 128 ++++++---
>  6 files changed, 531 insertions(+), 118 deletions(-)
> 
> -- 
> 2.7.4
> 
> 
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¹ https://lists.freedesktop.org/archives/dri-devel/2019-March/209685.html