Hi CK, Thanks for your quick answer. On 21/2/20 5:39, CK Hu wrote: > 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. > I understand what you mean but I am not sure this makes the code clearer and useful. The driver in drivers/soc/mediatek will be a simple dummy implementation of a "simple-mfd" device (a driver that simply matches with "mediatek,mt8173-mmsys" and instantiates the "clk-mt8173-mm" and the "mediatek-drm" driver (note that mediatek-mdp" is already instantiated via device-tree). It'd be nice had a proper device-tree with a "simple-mfd" for mmsys from the beginning representing how really hardwware is, but I think that, change this now, will break backward compatibility. IMHO I think that considering the clk driver as entry point is fine, but this is something that the clock maintainers should decide. Also note that this is not only a MT8173 problem I am seeing the same problem on all other Mediatek SoCs. Thanks. > 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 >> >
