Re: [PATCH v13 0/2] drm: add kms driver for loongson display controller

[Sui Jingfeng <15330273260@xxxxxx>]

Hi,

On 2023/5/18 21:38, Thomas Zimmermann wrote:
> Hi,
>
> I don't know the status here, but if it works, you should probably 
> merge it. I think you first need to get commit access to drm-misc. 
> That will also allow you to merge the other fixes you sent recently.
>
> See
>
>
> https://drm.pages.freedesktop.org/maintainer-tools/commit-access.html#drm-misc 
>
>
> for the overall process.
Thanks for you valuable advice, we don't know that before.

Currently, I'm not good enough to have a commit access.

I think I work hard to meet the requirement in the long term.

We observed that you are more professional programmer, and

you contribute a lot during the past.

We started developing driver by study your patches.

As you patch always come with good document and comments.

drm/loongson driver learns a lot from drm/ast, drm/qxl, drm/mgag200, 
drm/radeon.

also drm_gem_vram_helper.

Therefore, we are still believe that you are more professional at drm 
framework layer.

And there no doubt that you have a better understanding toward the 
atomic modeset than us.


We may have better knowledge about our hardware,

We also know that by keeping changes localized to drm/loongson,

It wouldn't make terrible influence on the drm core(and  other side).


Therefore, I would like invite you to be the co-maintainer of drm/loongson,

Would you like to accept this? If so I would like to update my patch and 
send V14.

I will  respect you decision, but I strongly encourage you to agree with 
this.

I believe that with your guidance and supervise, the quality of this 
driver can be guaranteed.


We could offer(donation) evaluation boards for patch verification,

see more information for the boards available at [1].

LoongArch boards has to burn new firmware before it can be used with 
upstream kernel.

Please give contact information to us if you are interested in. I will 
be helpful then because

I know how to burn new firmware.


[1] https://github.com/loongson/Firmware


By the way, Maxime is also the co-maintainer of drm/sun4i.

During the past there a lot reviewers participate in the process of 
reviewing drm/loognson.

including Maxime, Krzysztof, Christian, Emil, Rob, Chen and others.

so let's get it merged at next version, don't waste the reviewing effort 
ever made.


> Best regards
> Thomas
>
> Am 15.05.23 um 17:57 schrieb Sui Jingfeng:
> > Loongson display controller IP has been integrated in both Loongson 
> > north
> > bridge chipset(ls7a1000/ls7a2000) and Loongson 
> > SoCs(ls2k1000/ls2k2000), it
> > has been even included in Loongson self-made BMC products.
> >
> > This display controller is a PCI device. It has two display pipes and 
> > each
> > display pipe support a primary plane and a cursor plane. For the DC 
> > in the
> > ls7a1000 and ls2k1000, each display pipe has a DVO output interface 
> > which
> > provide RGB888 signals, vertical & horizontal synchronisations and pixel
> > clock. Each CRTC is able to support 1920x1080@60Hz, the maximum 
> > resolution
> > of each display pipe is 2048x2048 according to the hardware spec.
> >
> > For the DC in LS7A2000, each display pipe is equipped with a built-in 
> > HDMI
> > encoder which is compliant with the HDMI 1.4 specification, thus it 
> > support
> > 3840x2160@30Hz. The first display pipe is also equipped with a 
> > transparent
> > vga encoder which is parallel with the HDMI encoder. The DC in 
> > LS7A2000 is
> > more complete compare with the one in old chips, besides above 
> > feature, it
> > has two hardware cursors, two hardware vblank counter and two scanout
> > position recorders unit. It also support tiled framebuffer format which
> > can be scanout the tiled framebuffer rendered by the LoongGPU directly.
> >
> > v1 -> v2:
> >   1) Use hpd status reg when polling for ls7a2000
> >   2) Fix all warnings emerged when compile with W=1
> >
> > v2 -> v3:
> >   1) Add COMPILE_TEST in Kconfig and make the driver off by default
> >   2) Alphabetical sorting headers (Thomas)
> >   3) Untangle register access functions as much as possible (Thomas)
> >   4) Switch to TTM based memory manager and prefer cached mapping
> >      for Loongson SoC (Thomas)
> >   5) Add chip id detection method, now all models are distinguishable.
> >   6) Revise builtin HDMI phy driver, nearly all main stream mode
> >      below 4K@30Hz is tested, this driver supported these mode very
> >      well including clone display mode and extend display mode.
> >
> > v3 -> v4:
> >   1) Quickly fix a small mistake.
> >
> > v4 -> v5:
> >   1) Drop potential support for Loongson 2K series SoC temporary,
> >      this part should be resend with the DT binding patch in the future.
> >   2) Add per display pipe debugfs support to the builtin HDMI encoder.
> >   3) Rewrite atomic_update() for hardware cursors plane(Thomas)
> >   4) Rewrite encoder and connector initialization part, untangle it
> >      according to the chip(Thomas).
> >
> > v5 -> v6:
> >   1) Remove stray code which didn't get used, say 
> > lsdc_of_get_reserved_ram
> >   2) Fix all typos I could found, make sentences and code more readable
> >   3) Untangle lsdc_hdmi*_connector_detect() function according to the 
> > pipe
> >   4) After a serious consideration, we rename this driver as loongson.
> >      Because we also have drivers toward the LoongGPU IP in LS7A2000 and
> >      LS2K2000. Besides, there are also drivers about the external 
> > encoder,
> >      HDMI audio driver and vbios support etc. This patch only provide DC
> >      driver part, my teammate Li Yi believe that loongson will be more
> >      suitable for loongson graphics than lsdc in the long run.
> >
> >      loongson.ko = LSDC + LoongGPU + encoders driver + vbios/DT ...
> >
> > v6 -> v7:
> >   1) Add prime support, self-sharing is works. sharing buffer with 
> > etnaviv
> >      is also tested, and its works with limitation.
> >   2) Implement buffer objects tracking with list_head.
> >   3) S3(sleep to RAM) is tested on ls3a5000+ls7a2000 evb and it works.
> >   4) Rewrite lsdc_bo_move, since ttm core stop allocating resources
> >      during BO creation. Patch V1 ~ V6 of this series no longer works
> >      on latest kernel. Thus, we send V7 to revival them.
> >
> > v7 -> v8:
> >   1) Zero a compile warnnings on 32-bit platform, compile with W=1
> >   2) Revise lsdc_bo_gpu_offset() and minor cleanup
> >   3) Pageflip tested on the virtual terminal with following commands
> >
> >      modetest -M loongson -s 32:1920x1080 -v
> >      modetest -M loongson -s 34:1920x1080 -v -F tiles
> >
> >     It works like a charm, when running pageflip test with dual screnn
> >     configuration, another two additional bo created by the modetest
> >     emerged, VRAM usage up to 40+MB, well we have at least 64MB, still
> >     enough.
> >
> >     # cat bos
> >
> >         bo[0000]: size:     8112kB VRAM
> >         bo[0001]: size:       16kB VRAM
> >         bo[0002]: size:       16kB VRAM
> >         bo[0003]: size:    16208kB VRAM
> >         bo[0004]: size:     8112kB VRAM
> >         bo[0005]: size:     8112kB VRAM
> >
> > v8 -> v9:
> >   1) Select I2C and I2C_ALGOBIT in Kconfig and should depend on MMU.
> >   2) Using pci_get_domain_bus_and_slot to get the GPU device.
> >   3) Other minor improvements.
> >
> >   Those patches are tested on ls3a5000 + ls7a1000 CRB, ls3a5000 + 
> > ls7a2000
> >   evb, and lemote a1901 board(ls3a4000 + ls7a1000). On loongson mips 
> > CPU,
> >   the write combine support should be enabled, to get a decent 
> > performance
> >   for writing framebuffer data to the VRAM.
> >
> > v9 -> v10:
> >   1) Revise lsdc_drm_freeze() to implement S3 completely and correctly.
> >      I suddenly realized that pinned buffer can not move and VRAM lost
> >      power when sleep to RAM. Thus, the data in the buffer who is pinned
> >      in VRAM will get lost when resume. Yet it's not big problem because
> >      we are software rendering solution which relay on the CPU update 
> > the
> >      front framebuffer. We can see the garbage data when resume from S3,
> >      but the screen will show correct image as I move the cursor. 
> > This is
> >      due to the cpu repaint. v10 of this patch make S3 perfect by unpin
> >      all of BOs in VRAM, evict them all to system RAM.
> >
> > v10 -> v11:
> >   1) On double screen case, the single giant framebuffer is 
> > referenced by
> >      two GEM object, hence, it will be pinned by prepare_fb() at 
> > lease two
> >      times. This cause its pin count > 1. V10 of this patch only 
> > unpin VRAM
> >      BOs once when suspend, which is not correct on double screen 
> > case. V11
> >      of this patch unpin BOs until its pin count reach to zero when 
> > suspend.
> >      Then, we make the S3 support complete finally. With v11, I can't 
> > see
> >      any garbage data after resume. Tested on both ls7a1000 and ls7a2000
> >      platform, with single screen and double screen configuration.
> >   2) Fix vblank wait timeout when disable CRTC.
> >   3) Test against IGT, at least fbdev test and kms_flip test passed.
> >   4) Rewrite pixel PLL update function, magic numbers eliminated (Emil)
> >   5) Drop a few common hardware features description in lsdc_desc (Emil)
> >   6) Drop lsdc_mode_config_mode_valid(), instead add restrictions in 
> > dumb
> >      create function. (Emil)
> >   7) Untangle the ls7a1000 case and ls7a2000 case completely (Thomas)
> >
> > v11 -> v12:
> >   none
> >
> > v12 -> v13:
> >   1) Add benchmark to figure out the bandwidth of the hardware platform.
> >      Usage:
> >      # cd /sys/kernel/debug/dri/0/
> >      # cat benchmark
> >
> >   2) VRAM is filled with garbage data if uninitialized, add a buffer
> >      clearing procedure, clear it on the BO creation time.
> >   3) Update copyrights and adjust coding style (Huacai)
> >
> > Sui Jingfeng (2):
> >    drm: add kms driver for loongson display controller
> >    MAINTAINERS: add maintainers for DRM LOONGSON driver
> >
> >   MAINTAINERS                                 |    8 +
> >   drivers/gpu/drm/Kconfig                     |    2 +
> >   drivers/gpu/drm/Makefile                    |    1 +
> >   drivers/gpu/drm/loongson/Kconfig            |   17 +
> >   drivers/gpu/drm/loongson/Makefile           |   21 +
> >   drivers/gpu/drm/loongson/ls7a1000_outputs.c |  161 +++
> >   drivers/gpu/drm/loongson/ls7a2000_outputs.c |  531 +++++++++
> >   drivers/gpu/drm/loongson/lsdc_benchmark.c   |  132 +++
> >   drivers/gpu/drm/loongson/lsdc_benchmark.h   |   13 +
> >   drivers/gpu/drm/loongson/lsdc_crtc.c        | 1068 +++++++++++++++++++
> >   drivers/gpu/drm/loongson/lsdc_debugfs.c     |   91 ++
> >   drivers/gpu/drm/loongson/lsdc_device.c      |  104 ++
> >   drivers/gpu/drm/loongson/lsdc_drv.c         |  484 +++++++++
> >   drivers/gpu/drm/loongson/lsdc_drv.h         |  452 ++++++++
> >   drivers/gpu/drm/loongson/lsdc_gem.c         |  324 ++++++
> >   drivers/gpu/drm/loongson/lsdc_gem.h         |   37 +
> >   drivers/gpu/drm/loongson/lsdc_gfxpll.c      |  199 ++++
> >   drivers/gpu/drm/loongson/lsdc_gfxpll.h      |   52 +
> >   drivers/gpu/drm/loongson/lsdc_i2c.c         |  179 ++++
> >   drivers/gpu/drm/loongson/lsdc_i2c.h         |   29 +
> >   drivers/gpu/drm/loongson/lsdc_irq.c         |   81 ++
> >   drivers/gpu/drm/loongson/lsdc_irq.h         |   16 +
> >   drivers/gpu/drm/loongson/lsdc_output.h      |   21 +
> >   drivers/gpu/drm/loongson/lsdc_pixpll.c      |  481 +++++++++
> >   drivers/gpu/drm/loongson/lsdc_pixpll.h      |   86 ++
> >   drivers/gpu/drm/loongson/lsdc_plane.c       |  639 +++++++++++
> >   drivers/gpu/drm/loongson/lsdc_probe.c       |   56 +
> >   drivers/gpu/drm/loongson/lsdc_probe.h       |   12 +
> >   drivers/gpu/drm/loongson/lsdc_regs.h        |  400 +++++++
> >   drivers/gpu/drm/loongson/lsdc_ttm.c         |  610 +++++++++++
> >   drivers/gpu/drm/loongson/lsdc_ttm.h         |   99 ++
> >   31 files changed, 6406 insertions(+)
> >   create mode 100644 drivers/gpu/drm/loongson/Kconfig
> >   create mode 100644 drivers/gpu/drm/loongson/Makefile
> >   create mode 100644 drivers/gpu/drm/loongson/ls7a1000_outputs.c
> >   create mode 100644 drivers/gpu/drm/loongson/ls7a2000_outputs.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_benchmark.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_benchmark.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_crtc.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_debugfs.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_device.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_drv.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_drv.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_gem.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_gem.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_gfxpll.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_gfxpll.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_i2c.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_i2c.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_irq.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_irq.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_output.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_pixpll.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_pixpll.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_plane.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_probe.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_probe.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_regs.h
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_ttm.c
> >   create mode 100644 drivers/gpu/drm/loongson/lsdc_ttm.h