From: CK Hu <ck.hu@mediatek.com>
To: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: <mark.rutland@arm.com>,
Kate Stewart <kstewart@linuxfoundation.org>,
Minghsiu Tsai <minghsiu.tsai@mediatek.com>,
Andrew-CT Chen <andrew-ct.chen@mediatek.com>, <airlied@linux.ie>,
<mturquette@baylibre.com>, <dri-devel@lists.freedesktop.org>,
Richard Fontana <rfontana@redhat.com>,
<laurent.pinchart@ideasonboard.com>,
<ulrich.hecht+renesas@gmail.com>,
Collabora Kernel ML <kernel@collabora.com>,
<linux-clk@vger.kernel.org>,
Nicolas Boichat <drinkcat@chromium.org>,
Weiyi Lu <weiyi.lu@mediatek.com>,
Krzysztof Kozlowski <krzk@kernel.org>, <wens@csie.org>,
<linux-arm-kernel@lists.infradead.org>,
mtk01761 <wendell.lin@mediatek.com>,
Owen Chen <owen.chen@mediatek.com>, <linux-media@vger.kernel.org>,
<devicetree@vger.kernel.org>, Daniel Vetter <daniel@ffwll.ch>,
<frank-w@public-files.de>, Seiya Wang <seiya.wang@mediatek.com>,
<sean.wang@mediatek.com>, Houlong Wei <houlong.wei@mediatek.com>,
<robh+dt@kernel.org>, <linux-mediatek@lists.infradead.org>,
<hsinyi@chromium.org>, Matthias Brugger <matthias.bgg@gmail.com>,
"Thomas Gleixner" <tglx@linutronix.de>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Allison Randal <allison@lohutok.net>,
Matthias Brugger <mbrugger@suse.com>,
Fabien Parent <fparent@baylibre.com>, <sboyd@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
<rdunlap@infradead.org>, <linux-kernel@vger.kernel.org>,
<p.zabel@pengutronix.de>, <matthias.bgg@kernel.org>
Subject: Re: [PATCH v8 0/6] arm/arm64: mediatek: Fix mmsys device probing
Date: Fri, 21 Feb 2020 17:27:09 +0800 [thread overview]
Message-ID: <1582277229.25992.9.camel@mtksdaap41> (raw)
In-Reply-To: <7a87b486-1622-7f27-f5af-427b94a14c00@collabora.com>
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?
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@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-mediatek
next prev parent reply other threads:[~2020-02-21 9:27 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-20 17:21 [PATCH v8 0/6] arm/arm64: mediatek: Fix mmsys device probing Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 1/6] drm/mediatek: Use regmap for register access Enric Balletbo i Serra
2020-02-20 23:48 ` Randy Dunlap
2020-02-21 7:46 ` Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 2/6] drm/mediatek: Omit warning on probe defers Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 3/6] media: mtk-mdp: Check return value of of_clk_get Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 4/6] clk: mediatek: mt8173: Switch MMSYS to platform driver Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 5/6] drm/mediatek: Move MMSYS configuration to include/linux/platform_data Enric Balletbo i Serra
2020-02-20 17:21 ` [PATCH v8 6/6] clk/drm: mediatek: Fix mediatek-drm device probing Enric Balletbo i Serra
2020-02-21 5:18 ` CK Hu
2020-02-21 7:51 ` Enric Balletbo i Serra
2020-02-21 4:39 ` [PATCH v8 0/6] arm/arm64: mediatek: Fix mmsys " CK Hu
2020-02-21 8:56 ` Enric Balletbo i Serra
2020-02-21 9:27 ` CK Hu [this message]
2020-02-21 10:24 ` Matthias Brugger
2020-02-21 11:11 ` CK Hu
2020-02-21 11:37 ` Enric Balletbo i Serra
2020-02-21 11:53 ` Matthias Brugger
2020-02-21 17:10 ` Enric Balletbo i Serra
2020-02-24 5:52 ` CK Hu
2020-02-25 10:56 ` Enric Balletbo i Serra
2020-02-26 5:32 ` CK Hu
2020-02-26 9:24 ` Enric Balletbo i Serra
2020-02-21 10:20 ` Matthias Brugger
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