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Date:   Fri, 8 Dec 2023 10:14:19 +0100
From:   Maxime Ripard <mripard@kernel.org>
To:     Andy Yan <andyshrk@163.com>
Cc:     Keith Zhao <keith.zhao@starfivetech.com>,
        "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
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        <krzysztof.kozlowski+dt@linaro.org>,
        William Qiu <william.qiu@starfivetech.com>,
        Xingyu Wu <xingyu.wu@starfivetech.com>,
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        "aou@eecs.berkeley.edu" <aou@eecs.berkeley.edu>,
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        Shengyang Chen <shengyang.chen@starfivetech.com>,
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        <maarten.lankhorst@linux.intel.com>,
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Subject: Re: [v3 5/6] drm/vs: Add hdmi driver
Message-ID: <xevxqusbizjfs4qt5rufhntd3vd656o2smocvivvulzceh3aeu@uuihphhat5wi>
References: <20231204123315.28456-6-keith.zhao@starfivetech.com>
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 <40cdd3c7-174e-4611-9ea6-22cb56d1f62b@starfivetech.com>
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 <e0b84511-dbb4-46fa-9465-713369232f6f@starfivetech.com>
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 <e1c362dc-8aac-4d13-9356-8b7ccae4727f@starfivetech.com>
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Hi,

On Fri, Dec 08, 2023 at 11:23:37AM +0800, Andy Yan wrote:
> =E5=9C=A8 2023-12-08 11:00:31=EF=BC=8C"Keith Zhao" <keith.zhao@starfivete=
ch.com> =E5=86=99=E9=81=93=EF=BC=9A
> >
> >
> >On 2023/12/8 8:37, Andy Yan wrote:
> >> Hi Keth=EF=BC=9A
> >>=20
> >>=20
> >>=20
> >>=20
> >>=20
> >>=20
> >> =E5=9C=A8 2023-12-07 18:48:13=EF=BC=8C"Keith Zhao" <keith.zhao@starfiv=
etech.com> =E5=86=99=E9=81=93=EF=BC=9A
> >>>
> >>>
> >>>On 2023/12/7 17:02, Andy Yan wrote:
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>> Hi Keith=EF=BC=9A
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>>=20
> >>>> At 2023-12-06 22:11:33, "Keith Zhao" <keith.zhao@starfivetech.com> w=
rote:
> >>>>>
> >>>>>
> >>>>>On 2023/12/6 20:56, Maxime Ripard wrote:
> >>>>>> On Wed, Dec 06, 2023 at 08:02:55PM +0800, Keith Zhao wrote:
> >>>>>>> >> +static const struct of_device_id starfive_hdmi_dt_ids[] =3D {
> >>>>>>> >> +	{ .compatible =3D "starfive,jh7110-inno-hdmi",},
> >>>>>>> >=20
> >>>>>>> > So it's inno hdmi, just like Rockchip then?
> >>>>>>> >=20
> >>>>>>> > This should be a common driver.
> >>>>>>>
> >>>>>>> Rockchip has a inno hdmi IP. and Starfive has a inno hdmi IP.
> >>>>>>> but the harewawre difference of them is big , it is not easy to u=
se the common driver
> >>>>>>> maybe i need the inno hdmi version here to make a distinction
> >>>>>>=20
> >>>>>> I just had a look at the rockchip header file: all the registers b=
ut the
> >>>>>> STARFIVE_* ones are identical.
> >>>>>>=20
> >>>>>> There's no need to have two identical drivers then, please use the
> >>>>>> rockchip driver instead.
> >>>>>>=20
> >>>>>> Maxime
> >>>>>
> >>>>>ok, have a simple test , edid can get . i will continue=20
> >>>>=20
> >>>> Maybe you can take drivers/gpu/drm/bridge/synopsys/dw-hdmi as a refe=
rence=EF=BC=8C this
> >>>> is also a hdmi ip used by rockchip/meson/sunxi/jz/imx=E3=80=82
> >>>> We finally make it share one driver=E3=80=82
> >>>>>
> >>>hi Andy:
> >>>
> >>>dw_hdmi seems a good choice , it can handle inno hdmi hardware by defi=
ne its dw_hdmi_plat_data.
> >>>does it means i can write own driver files such as(dw_hdmi-starfive.c)=
 based on dw_hdmi instead of add plat_data in inno_hdmi.c
> >>>
> >>=20
> >> I think the process maybe like this=EF=BC=9A
> >>=20
> >> 1. split the inno_hdmi.c under rockchip to  inno_hdmi.c(the common par=
t), inno_hdmi-rockchip.c(the soc specific part)
> >> 2. move the common part inno_hdmi.c to drivers/gpu/drm/bridge/innosili=
con/
> >> 3. add startfive specific part, inno_hdmi-startfive.c
> >>=20
> >> bellow git log from kernel three show how we convert  dw_hdmi to a com=
mon driver:=20
> >>=20
> >>=20
> >>=20
> >> 12b9f204e804 drm: bridge/dw_hdmi: add rockchip rk3288 support
> >> 74af9e4d03b8 dt-bindings: Add documentation for rockchip dw hdmi
> >> d346c14eeea9 drm: bridge/dw_hdmi: add function dw_hdmi_phy_enable_spare
> >> a4d3b8b050d5 drm: bridge/dw_hdmi: clear i2cmphy_stat0 reg in hdmi_phy_=
wait_i2c_done
> >> 632d035bace2 drm: bridge/dw_hdmi: add mode_valid support
> >> 0cd9d1428322 drm: bridge/dw_hdmi: add support for multi-byte register =
width access
> >> cd152393967e dt-bindings: add document for dw_hdmi
> >> b21f4b658df8 drm: imx: imx-hdmi: move imx-hdmi to bridge/dw_hdmi
> >> aaa757a092c2 drm: imx: imx-hdmi: split phy configuration to platform d=
river
> >> 3d1b35a3d9f3 drm: imx: imx-hdmi: convert imx-hdmi to drm_bridge mode
> >> c2c3848851a7 drm: imx: imx-hdmi: return defer if can't get ddc i2c ada=
pter
> >> b587833933de drm: imx: imx-hdmi: make checkpatch happy
> >>=20
> >hi Andy:
> >I got you means,=20
> >as I don't have a rockchip board on hand , to split the inno_hdmi.c can =
not be tested.
> >
> >how adout this idea:
> >1=E3=80=81split the starfive_hdmi.c under verisilicion to  inno_hdmi.c(t=
he common part), inno_hdmi-starfive.c(the soc specific part)
> >2. move the common part inno_hdmi.c to drivers/gpu/drm/bridge/innosilico=
n/
> >3. In the future, inno hdmi.c under rockchip will reuse the public drive=
r.
>=20
> I am not sure if drm maintainers are happy with this=E3=80=82

Not really, no.

Because we would still have two drivers for the same controller, and a
common one that haven't really been tested on anything but a single
platform. So arguably a worse situation than what you were suggesting in
the first place.

The best solution would be to find someone with a Rockchip board to test
your changes, or to get one if it's doable so you can test yourself.

Maxime

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