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Date:   Fri, 17 Jul 2020 12:45:17 +0300
From:   Laurentiu Palcu <laurentiu.palcu@oss.nxp.com>
To:     Lucas Stach <l.stach@pengutronix.de>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Laurentiu Palcu <laurentiu.palcu@nxp.com>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        devicetree <devicetree@vger.kernel.org>,
        Guido =?iso-8859-1?Q?G=FCnther?= <agx@sigxcpu.org>,
        lukas@mntmn.com,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v5 0/4] Add support for iMX8MQ Display Controller
 Subsystem
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Hi Lukas and Daniel,

On Fri, Jul 17, 2020 at 11:27:58AM +0200, Daniel Vetter wrote:
> On Fri, Jul 17, 2020 at 11:12:39AM +0200, Lucas Stach wrote:
> > Am Freitag, den 17.07.2020, 10:59 +0200 schrieb Daniel Vetter:
> > > On Fri, Jul 17, 2020 at 10:18 AM Lucas Stach <l.stach@pengutronix.de> wrote:
> > > > Hi Laurentiu,
> > > > 
> > > > Am Donnerstag, den 09.07.2020, 19:47 +0300 schrieb Laurentiu Palcu:
> > > > > From: Laurentiu Palcu <laurentiu.palcu@nxp.com>
> > > > > 
> > > > > Hi,
> > > > > 
> > > > > This patchset adds initial DCSS support for iMX8MQ chip. Initial support
> > > > > includes only graphics plane support (no video planes), no HDR10 capabilities,
> > > > > no graphics decompression (only linear, tiled and super-tiled buffers allowed).
> > > > > 
> > > > > Support for the rest of the features will be added incrementally, in subsequent
> > > > > patches.
> > > > > 
> > > > > The patchset was tested with both HDP driver (in the downstream tree) and the upstream
> > > > > MIPI-DSI driver (with a couple of patches on top, to make it work correctly with DCSS).
> > > > 
> > > > I think the series (minus 3/5 and minor correction to the DT binding)
> > > > is fine to go in now. So just some formal questions: are you going to
> > > > maintain this driver in upstream? If so we should add a MAINTAINERS
> > > > entry to that effect. I can offer to act as a reviewer in this case.

I can maintain the DCSS driver, sure, and the more reviewers the better.
Thanks for helping out with this. Should I send a v6 then with a patch
for MAINTAINERS?

> > > > 
> > > > How do you intend to merge this? IMO pushing this through drm-misc
> > > > seems like the right thing to do. If you agree I can help you get this
> > > > applied. If you are going to maintain the driver on your own, I think
> > > > you should then apply for commit rights to drm-misc.
> > > 
> > > drm/imx isn't listed yet as under the drm-misc umbrella, maybe we
> > > should put the entire collective of imx drivers under drm-misc? Or
> > > maybe it's just an oversight that the git repo isn't specified in the
> > > MAINTAINERS entry. Also maybe we should add the pengutronix kernel
> > > team alias there too?
> > 
> > drm/imx was exclusively the IPUv3 up until now, which is in fact
> > maintained outside of drm-misc in its own git tree. This has worked
> > quite well in the past so even though IPUv3 doesn't see a lot of churn
> > these days the motivation to change anything to this workflow is quite
> > low. And yes, the git tree is missing from the MAINTAINERS entry.
> > 
> > For the DCSS driver, if it's going to be maintained by NXP, I figured
> > it might be easier for Laurentiu to push things into drm-misc than set
> > up a separate public git tree. But IMHO that's fully up to him to
> > decide.
> 
> /me puts on maintainer hat
> 
> Much prefer drm-misc over random people playing maintainer and fumbling
> it. I think the reasonable options are either in the current imx tree, or
> drm-misc. Standalone tree for these small drivers just doesn't make much
> sense.

I don't have anything against either method, though I have to agree I
like things to be simple. Going through drm-misc sounds simple enough to me. :)
However, since there is going to be more activity in the DRM IMX area in
the future, reviving the drm/imx tree, and push all IMX related stuff
through drm/imx, could make sense as well.

Thanks,
Laurentiu

> -Daniel
> 
> > 
> > Regards,
> > Lucas
> > 
> > > -Daniel
> > > 
> > > 
> > > > Regards,
> > > > Lucas
> > > > 
> > > > > Thanks,
> > > > > Laurentiu
> > > > > 
> > > > > Changes in v5:
> > > > >  * Rebased to latest;
> > > > >  * Took out component framework support and made it a separate patch so
> > > > >    that people can still test with HDP driver, which makes use of it.
> > > > >    But the idea is to get rid of it once HDP driver's next versions
> > > > >    will remove component framework as well;
> > > > >  * Slight improvement to modesetting: avoid cutting off the pixel clock
> > > > >    if the new mode and the old one are equal. Also, in this case, is
> > > > >    not necessary to wait for DTG to shut off. This would allow to switch
> > > > >    from 8b RGB to 12b YUV422, for example, with no interruptions (at least
> > > > >    from DCSS point of view);
> > > > >  * Do not fire off CTXLD when going to suspend, unless it still has
> > > > >    entries that need to be committed to DCSS;
> > > > >  * Addressed Rob's comments on bindings;
> > > > > 
> > > > > Changes in v4:
> > > > >  * Addressed Lucas and Philipp's comments:
> > > > >    * Added DRM_KMS_CMA_HELPER dependency in Kconfig;
> > > > >    * Removed usage of devm_ functions since I'm already doing all the
> > > > >      clean-up in the submodules_deinit();
> > > > >    * Moved the drm_crtc_arm_vblank_event() in dcss_crtc_atomic_flush();
> > > > >    * Removed en_completion variable from dcss_crtc since this was
> > > > >      introduced mainly to avoid vblank timeout warnings which were fixed
> > > > >      by arming the vblank event in flush() instead of begin();
> > > > >    * Removed clks_on and irq_enabled flags since all the calls to
> > > > >      enabling/disabling clocks and interrupts were balanced;
> > > > >    * Removed the custom atomic_commit callback and used the DRM core
> > > > >      helper and, in the process, got rid of a workqueue that wasn't
> > > > >      necessary anymore;
> > > > >    * Fixed some minor DT binding issues flagged by Philipp;
> > > > >    * Some other minor changes suggested by Lucas;
> > > > >  * Removed YUV formats from the supported formats as these cannot work
> > > > >    without the HDR10 module CSCs and LUTs. Will add them back when I
> > > > >    will add support for video planes;
> > > > > 
> > > > > Changes in v3:
> > > > >  * rebased to latest linux-next and made it compile as drmP.h was
> > > > >    removed;
> > > > >  * removed the patch adding the VIDEO2_PLL clock. It's already applied;
> > > > >  * removed an unnecessary 50ms sleep in the dcss_dtg_sync_set();
> > > > >  * fixed a a spurious hang reported by Lukas Hartmann and encountered
> > > > >    by me several times;
> > > > >  * mask DPR and DTG interrupts by default, as they may come enabled from
> > > > >    U-boot;
> > > > > 
> > > > > Changes in v2:
> > > > >  * Removed '0x' in node's unit-address both in DT and yaml;
> > > > >  * Made the address region size lowercase, to be consistent;
> > > > >  * Removed some left-over references to P010;
> > > > >  * Added a Kconfig dependency of DRM && ARCH_MXC. This will also silence compilation
> > > > >    issues reported by kbuild for other architectures;
> > > > > 
> > > > > Laurentiu Palcu (5):
> > > > >   drm/imx: compile imx directory by default
> > > > >   drm/imx: Add initial support for DCSS on iMX8MQ
> > > > >   drm/imx/dcss: add component framework functionality
> > > > >   dt-bindings: display: imx: add bindings for DCSS
> > > > >   arm64: dts: imx8mq: add DCSS node
> > > > > 
> > > > >  .../bindings/display/imx/nxp,imx8mq-dcss.yaml |  84 ++
> > > > >  arch/arm64/boot/dts/freescale/imx8mq.dtsi     |  23 +
> > > > >  drivers/gpu/drm/Makefile                      |   2 +-
> > > > >  drivers/gpu/drm/imx/Kconfig                   |   2 +
> > > > >  drivers/gpu/drm/imx/Makefile                  |   1 +
> > > > >  drivers/gpu/drm/imx/dcss/Kconfig              |   9 +
> > > > >  drivers/gpu/drm/imx/dcss/Makefile             |   6 +
> > > > >  drivers/gpu/drm/imx/dcss/dcss-blkctl.c        |  70 ++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-crtc.c          | 219 +++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-ctxld.c         | 424 +++++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-dev.c           | 314 +++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-dev.h           | 177 ++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-dpr.c           | 562 ++++++++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-drv.c           | 183 ++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-dtg.c           | 409 +++++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-kms.c           | 185 ++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-kms.h           |  43 +
> > > > >  drivers/gpu/drm/imx/dcss/dcss-plane.c         | 405 +++++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-scaler.c        | 826 ++++++++++++++++++
> > > > >  drivers/gpu/drm/imx/dcss/dcss-ss.c            | 180 ++++
> > > > >  20 files changed, 4123 insertions(+), 1 deletion(-)
> > > > >  create mode 100644 Documentation/devicetree/bindings/display/imx/nxp,imx8mq-dcss.yaml
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/Kconfig
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/Makefile
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-blkctl.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-crtc.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-ctxld.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-dev.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-dev.h
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-dpr.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-drv.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-dtg.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-kms.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-kms.h
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-plane.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-scaler.c
> > > > >  create mode 100644 drivers/gpu/drm/imx/dcss/dcss-ss.c
> > > > > 
> > > > 
> > > > _______________________________________________
> > > > dri-devel mailing list
> > > > dri-devel@lists.freedesktop.org
> > > > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> > > 
> > > 
> > 
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch