Re: [RFC v2 0/5] Common Display Framework

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Vikas,

On Tuesday 18 December 2012 08:31:30 Vikas Sajjan wrote:
> On 17 December 2012 20:55, Laurent Pinchart wrote:
> > Hi Vikas,
> > 
> > Sorry for the late reply. I now have more time to work on CDF, so delays
> > should be much shorter.
> > 
> > On Thursday 06 December 2012 10:51:15 Vikas Sajjan wrote:
> > > Hi Laurent,
> > > 
> > > I was thinking of porting CDF to samsung EXYNOS 5250 platform, what I
> > > found is that, the exynos display controller is MIPI DSI based
> > > controller.
> > > 
> > > But if I look at CDF patches, it has only support for MIPI DBI based
> > > Display controller.
> > > 
> > > So my question is, do we have any generic framework for MIPI DSI based
> > > display controller? basically I wanted to know, how to go about porting
> > > CDF for such kind of display controller.
> > 
> > MIPI DSI support is not available yet. The only reason for that is that I
> > don't have any MIPI DSI hardware to write and test the code with :-)
> > 
> > The common display framework should definitely support MIPI DSI. I think
> > the existing MIPI DBI code could be used as a base, so the implementation
> > shouldn't be too high.
> > 
> > Yeah, i was also thinking in similar lines, below is my though for MIPI
> > DSI support in CDF.
> 
> o MIPI DSI support as part of CDF framework will expose
>   § mipi_dsi_register_device(mpi_device) (will be called mach-xxx-dt.c
>     file)
>   § mipi_dsi_register_driver(mipi_driver, bus ops) (will be called from
>     platform specific init driver call )
>     · bus ops will be
>       o read data
>       o write data
>       o write command
>  § MIPI DSI will be registered as bus_register()
> 
> When MIPI DSI probe is called, it (e.g., Exynos or OMAP MIPI DSI) will
> initialize the MIPI DSI HW IP.
> 
> This probe will also parse the DT file for MIPI DSI based panel, add
> the panel device (device_add() ) to kernel and register the display
> entity with its control and  video ops with CDF.

After discussing the DBI/DSI busses with Tomi Valkeinen we concluded that 
creating a real bus for DBI and DSI, although possible, wasn't required. DSI 
operations should thus be provided through display entity video source 
operations. You can find a proposed implementation in Tomi's patch set.

> > I can give this a try. Does the existing Exynos 5250 driver support MIPI
> > DSI ? Is the device documentation publicly available ? Can you point me to
> > a MIPI DSI panel with public documentation (preferably with an existing
> > mainline driver if possible) ?
>
> yeah, existing Exynos 5250 driver support MIPI DSI ass well as eDP.
> 
>  i think device documentation is NOT available publicly.

-- 
Regards,

Laurent Pinchart