Hi, Matthias: On Fri, 2020-02-21 at 11:24 +0100, Matthias Brugger wrote: > > On 21/02/2020 10:27, CK Hu wrote: > > Hi, Enric: > > > > On Fri, 2020-02-21 at 09:56 +0100, Enric Balletbo i Serra wrote: > >> 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's clear that mmsys is neither a pure clock controller nor a pure > > routing controller for display and mdp. > > > >> 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. > > > > Maybe this is a solution. Current device tree would work only on old > > kernel version with a bug, so this mean there is no any device tree > > works on kernel version without bug. Why do we compatible with such > > device tree? > > > > The idea behind this is, that the device-tree could be passed by some boot > firmware, so that the OS do not care about it. For this we need a stable DTS as > otherwise newer kernel with older FW would break. > > DTS is supposed to be just a different description of the HW like ACPI. So it > has to be compatible (newer kernel with older DTS and if possible vice versa). In my view, there is no FW (except some bug-inside FW) which works on this dts, so this dts is in a initial state. I think the compatibility is based on that dts correctly describe the HW. If we find this dts does not correctly describe the HW and it's in a initial state, should we still make it compatible? If you have better solution, just let's forget this. Regards, CK > > Regards, > Matthias > > > Regards, > > CK > > > >> > >> 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 > >>>> > >>> > >> > >> _______________________________________________ > >> Linux-mediatek mailing list > >> Linux-mediatek@xxxxxxxxxxxxxxxxxxx > >> http://lists.infradead.org/mailman/listinfo/linux-mediatek > > > > _______________________________________________ > Linux-mediatek mailing list > Linux-mediatek@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-mediatek
