Re: [PATCH v8 0/6] arm/arm64: mediatek: Fix mmsys device probing

[CK Hu <ck.hu@mediatek.com>]

Hi, Enric:

On Thu, 2020-02-20 at 18:21 +0100, Enric Balletbo i Serra wrote:
> Dear all,
> 
> Those patches are intended to solve an old standing issue on some
> Mediatek devices (mt8173, mt2701 and mt2712) in a slightly different way
> to the precedent series.
> 
> Up to now both drivers, clock and drm are probed with the same device tree
> compatible. But only the first driver get probed, which in effect breaks
> graphics on those devices.
> 
> The version eight of the series tries to solve the problem with a
> different approach than the previous series but similar to how is solved
> on other Mediatek devices.
> 
> The MMSYS (Multimedia subsystem) in Mediatek SoCs has some registers to
> control clock gates (which is used in the clk driver) and some registers
> to set the routing and enable the differnet blocks of the display
> and MDP (Media Data Path) subsystem. On this series the clk driver is
> not a pure clock controller but a system controller that can provide
> access to the shared registers between the different drivers that need
> it (mediatek-drm and mediatek-mdp). And the biggest change is, that in
> this version, clk driver is the entry point (parent) which will trigger
> the probe of the corresponding mediatek-drm driver and pass its MMSYS
> platform data for display configuration.

When mmsys is a system controller, I prefer to place mmsys in
drivers/soc/mediatek, and it share registers for clock, display, and mdp
driver. This means the probe function is placed in
drivers/soc/mediatek ,its display clock function, mdp clock function are
placed in drivers/clk, display routing are placed in drivers/gpu/drm,
and mdp routing are placed in dirvers/video.

Regards,
CK

> 
> All this series was tested on the Acer R13 Chromebook only.
> 
> For reference, here are the links to the old discussions:
> 
> * v7: https://patchwork.kernel.org/project/linux-mediatek/list/?series=241217
> * v6: https://patchwork.kernel.org/project/linux-mediatek/list/?series=213219
> * v5: https://patchwork.kernel.org/project/linux-mediatek/list/?series=44063
> * v4:
>   * https://patchwork.kernel.org/patch/10530871/
>   * https://patchwork.kernel.org/patch/10530883/
>   * https://patchwork.kernel.org/patch/10530885/
>   * https://patchwork.kernel.org/patch/10530911/
>   * https://patchwork.kernel.org/patch/10530913/
> * v3:
>   * https://patchwork.kernel.org/patch/10367857/
>   * https://patchwork.kernel.org/patch/10367861/
>   * https://patchwork.kernel.org/patch/10367877/
>   * https://patchwork.kernel.org/patch/10367875/
>   * https://patchwork.kernel.org/patch/10367885/
>   * https://patchwork.kernel.org/patch/10367883/
>   * https://patchwork.kernel.org/patch/10367889/
>   * https://patchwork.kernel.org/patch/10367907/
>   * https://patchwork.kernel.org/patch/10367909/
>   * https://patchwork.kernel.org/patch/10367905/
> * v2: No relevant discussion, see v3
> * v1:
>   * https://patchwork.kernel.org/patch/10016497/
>   * https://patchwork.kernel.org/patch/10016499/
>   * https://patchwork.kernel.org/patch/10016505/
>   * https://patchwork.kernel.org/patch/10016507/
> 
> Best regards,
>  Enric
> 
> Changes in v8:
> - Be a builtin_platform_driver like other mediatek mmsys drivers.
> - New patches introduced in this series.
> 
> Changes in v7:
> - Add R-by from CK
> - Add R-by from CK
> - Fix check of return value of of_clk_get
> - Fix identation
> - Free clk_data->clks as well
> - Get rid of private data structure
> 
> Enric Balletbo i Serra (2):
>   drm/mediatek: Move MMSYS configuration to include/linux/platform_data
>   clk/drm: mediatek: Fix mediatek-drm device probing
> 
> Matthias Brugger (4):
>   drm/mediatek: Use regmap for register access
>   drm/mediatek: Omit warning on probe defers
>   media: mtk-mdp: Check return value of of_clk_get
>   clk: mediatek: mt8173: Switch MMSYS to platform driver
> 
>  drivers/clk/mediatek/Kconfig                  |   6 +
>  drivers/clk/mediatek/Makefile                 |   1 +
>  drivers/clk/mediatek/clk-mt2701-mm.c          |  30 +++
>  drivers/clk/mediatek/clk-mt2712-mm.c          |  44 +++++
>  drivers/clk/mediatek/clk-mt8173-mm.c          | 172 ++++++++++++++++++
>  drivers/clk/mediatek/clk-mt8173.c             | 104 -----------
>  drivers/gpu/drm/mediatek/mtk_disp_color.c     |   5 +-
>  drivers/gpu/drm/mediatek/mtk_disp_ovl.c       |   5 +-
>  drivers/gpu/drm/mediatek/mtk_disp_rdma.c      |   5 +-
>  drivers/gpu/drm/mediatek/mtk_dpi.c            |  12 +-
>  drivers/gpu/drm/mediatek/mtk_drm_crtc.c       |   4 +-
>  drivers/gpu/drm/mediatek/mtk_drm_ddp.c        |  53 +++---
>  drivers/gpu/drm/mediatek/mtk_drm_ddp.h        |   4 +-
>  drivers/gpu/drm/mediatek/mtk_drm_ddp_comp.h   |  56 +-----
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c        | 113 +-----------
>  drivers/gpu/drm/mediatek/mtk_drm_drv.h        |  13 +-
>  drivers/gpu/drm/mediatek/mtk_dsi.c            |   8 +-
>  drivers/gpu/drm/mediatek/mtk_hdmi.c           |   4 +-
>  drivers/media/platform/mtk-mdp/mtk_mdp_comp.c |   6 +
>  include/linux/platform_data/mtk_mmsys.h       |  73 ++++++++
>  20 files changed, 401 insertions(+), 317 deletions(-)
>  create mode 100644 drivers/clk/mediatek/clk-mt8173-mm.c
>  create mode 100644 include/linux/platform_data/mtk_mmsys.h
>