RE: [PATCH v2 0/2] Add waveshare 7inch touchscreen panel support

[Shengyang Chen]

Hi, Neil

> -----Original Message-----
> From: neil.armstrong@xxxxxxxxxx <neil.armstrong@xxxxxxxxxx>
> Sent: 2024年1月16日 17:34
> To: Shengyang Chen <shengyang.chen@xxxxxxxxxxxxxxxx>;
> devicetree@xxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: quic_jesszhan@xxxxxxxxxxx; sam@xxxxxxxxxxxx; airlied@xxxxxxxxx;
> daniel@xxxxxxxx; maarten.lankhorst@xxxxxxxxxxxxxxx; mripard@xxxxxxxxxx;
> tzimmermann@xxxxxxx; robh+dt@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx; wahrenst@xxxxxxx;
> dave.stevenson@xxxxxxxxxxxxxxx; thierry.reding@xxxxxxxxx; Changhuang
> Liang <changhuang.liang@xxxxxxxxxxxxxxxx>; Keith Zhao
> <keith.zhao@xxxxxxxxxxxxxxxx>; Jack Zhu <jack.zhu@xxxxxxxxxxxxxxxx>;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2 0/2] Add waveshare 7inch touchscreen panel support
> 
> On 16/01/2024 10:32, Shengyang Chen wrote:
> > Hi, Neil
> >
> > Thanks for your comment.
> >
> >> -----Original Message-----
> >> From: neil.armstrong@xxxxxxxxxx <neil.armstrong@xxxxxxxxxx>
> >> Sent: 2024年1月9日 19:19
> >> To: Shengyang Chen <shengyang.chen@xxxxxxxxxxxxxxxx>;
> >> devicetree@xxxxxxxxxxxxxxx; dri-devel@xxxxxxxxxxxxxxxxxxxxx
> >> Cc: quic_jesszhan@xxxxxxxxxxx; sam@xxxxxxxxxxxx; airlied@xxxxxxxxx;
> >> daniel@xxxxxxxx; maarten.lankhorst@xxxxxxxxxxxxxxx;
> >> mripard@xxxxxxxxxx; tzimmermann@xxxxxxx; robh+dt@xxxxxxxxxx;
> >> krzysztof.kozlowski+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx;
> >> wahrenst@xxxxxxx; dave.stevenson@xxxxxxxxxxxxxxx;
> >> thierry.reding@xxxxxxxxx; Changhuang Liang
> >> <changhuang.liang@xxxxxxxxxxxxxxxx>; Keith Zhao
> >> <keith.zhao@xxxxxxxxxxxxxxxx>; Jack Zhu <jack.zhu@xxxxxxxxxxxxxxxx>;
> >> linux-kernel@xxxxxxxxxxxxxxx
> >> Subject: Re: [PATCH v2 0/2] Add waveshare 7inch touchscreen panel
> >> support
> >>
> >> Hi,
> >>
> >> On 09/01/2024 08:09, Shengyang Chen wrote:
> >>> This patchset adds waveshare 7inch touchscreen panel support for the
> >>> StarFive JH7110 SoC.
> >>
> >> Could you precise which SKU you're referring to ? is it 19885 =>
> >> https://www.waveshare.com/7inch-dsi-lcd.htm ?
> >>
> >
> > yes, it is
> > sorry for confusing you.
> >
> >> Are you sure it requires different timings from the RPi one ? In the
> >> Waveshare wiki it explicitly uses the rpi setup (vc4-kms-dsi-7inch) to drive it:
> >> https://www.waveshare.com/wiki/7inch_DSI_LCD
> >>
> >
> > Referring to Keith's answer
> > https://lists.freedesktop.org/archives/dri-devel/2023-December/434200.
> > html the panel timing value is generated to fit phy's bitrate and
> > prevent overflow and underflow.
> >
> > Referring to the suggestion, we may try other timing from panel-simple to
> drive the panel.
> 
> Please implement a mode_fixup in your DSI host driver instead.
> 

The mode fixup method is already used. As reference:
https://patchwork.kernel.org/project/dri-devel/patch/20240109072516.24328-3-shengyang.chen@xxxxxxxxxxxxxxxx/
you can check it in cdns_dsi_jh7110_update(). 
This code is being reviewed and may need to be optimized later.

> Neil
> 
> >
> >> Neil
> >>
> >>>
> >>>
> >>> changes since v1:
> >>> - Rebased on tag v6.7.
> >>>
> >>> patch 1:
> >>> - Gave up original changing.
> >>> - Changed the commit message.
> >>> - Add compatible in panel-simple.yaml
> >>>
> >>> patch 2:
> >>> - Gave up original changing.
> >>> - Changed the commit message.
> >>> - Add new mode for the panel in panel-simple.c
> >>>
> >>> v1:
> >>> https://patchwork.kernel.org/project/dri-devel/cover/20231124104451.
> >>> 44 271-1-shengyang.chen@xxxxxxxxxxxxxxxx/
> >>>
> >>> Shengyang Chen (2):
> >>>     dt-bindings: display: panel: panel-simple: Add compatible property for
> >>>       waveshare 7inch touchscreen panel
> >>>     gpu: drm: panel: panel-simple: add new display mode for waveshare
> >>>       7inch touchscreen panel
> >>>
> >>>    .../bindings/display/panel/panel-simple.yaml  |  2 ++
> >>>    drivers/gpu/drm/panel/panel-simple.c          | 28
> >> +++++++++++++++++++
> >>>    2 files changed, 30 insertions(+)
> >>>
> >
> >
> > Best Regards,
> > Shengyang

Best Regards,
Shengyang