Re: [PATCH 0/2] drm: imx: Add NWL MIPI DSI host controller support

["Guido Günther" <agx@sigxcpu.org>]

Hi Lucas,
On Mon, May 27, 2019 at 03:36:53PM +0200, Lucas Stach wrote:
> Am Mittwoch, den 08.05.2019, 19:18 +0200 schrieb Guido Günther:
> > Hi,
> > On Thu, Mar 07, 2019 at 11:30:51AM +0100, Guido Günther wrote:
> > > This adds initial support for the NWL MIPI DSI Host controller found on i.MX8
> > > SoCs.
> > > 
> > > It adds support for the i.MX8MQ but the same IP core can also be found on e.g.
> > > i.MX8QXP. I added the necessary hooks to support other imx8 variants but since
> > > I only have imx8mq boards to test I omitted the platform data for other SoCs.
> > > 
> > > The code is based on NXPs BSP so I added Robert Chiras as Co-authored-by but
> > > I'm happy to swap Author: and Co-authored-by: if that looks more appropriate.
> > > The most notable changes over the BSP driver are
> > >  - Calculate HS mode timing from phy_configure_opts_mipi_dphy
> > >  - Perform all clock setup via DT
> > >  - Merge nwl-imx and nwl drivers
> > >  - Add B0 silion revision quirk
> > > 
> > > Posting this is likely a bit premature (hence v0) but I wanted for one show how
> > > this hooks into the mixel dphy posted earlier [1] and avoid duplicating work.
> > > So if there's other code out there doing the same I'm be happy to merge
> > > efforts.
> > 
> > Since this is likely not going anywhere until we have a dcss driver aimed
> > for mainline I'm not going spam the list with further revisions. However
> > the 5.x version is maintained here:
> > 
> >     https://source.puri.sm/guido.gunther/linux-imx8/tree/forward-upstream/next-20190506/imx-nwl/v1-wip
> > 
> > Feedback is still welcome. It'll eventually be forwarded to newer
> > linux-next versions.
> > 
> > Changes over the posted version are:
> > 
> > - Add quirk for IMQ8MQ silicon B0 revision to not mess with the
> >   system reset controller on power down since enable won't work
> >   afterwards otherwise.
> > - Disable tx esc clock *after* the phy power down to unbreak
> >   disable/enable (unblank/blank)
> > - Drop devm_free_irq() handled by the device driver core
> > - Add ports to dt binding docs
> > - Select GENERIC_PHY_MIPI_DPHY instead of GENERIC_PHY for
> >   phy_mipi_dphy_get_default_config
> > - Include drm_print.h to fix build on next-20190408
> > - Drop some debugging messages
> > - Newline terminate all DRM_ printouts
> > 
> > If somebody is working on DCSS support it'd be cool to know since this
> > driver is currently a component of imx-display-subsystem which will only
> > work out if dcss is handled like this as well.
> 
> We have been looking at how to support DCSS in mainline for a while,
> but most of the actual work got pushed behind in schedule due to other
> priorities.
> 
> One thing I can can say for certain is that DCSS should not be
> integrated into imx-drm. It's a totally different hardware and
> downstream clearly shows that it's not a good idea to cram it into imx-
> drm.
> 
> Also the artificial split between hardware control in
> drivers/gpu/imx/dcss and the DRM driver is just cargo-cult from the
> IPU/imx-drm split. For the IPU we did it as the IPU has legs in both
> DRM for the output parts and V4L2 for the input parts. As the DCSS has
> no video input capabilities the driver could be simplified a lot by
> moving it all into a single DRM driver.

I agree. While moving if forward from NXPs tree this caused more trouble
than good so let's keep it separate form imx-drm.
Cheers,
 -- Guido
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