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

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Date: Tue, 16 Jan 2024 10:02:15 +0000
From: Shengyang Chen <shengyang.chen@...rfivetech.com>
To: "neil.armstrong@...aro.org" <neil.armstrong@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>
CC: "quic_jesszhan@...cinc.com" <quic_jesszhan@...cinc.com>,
	"sam@...nborg.org" <sam@...nborg.org>, "airlied@...il.com"
	<airlied@...il.com>, "daniel@...ll.ch" <daniel@...ll.ch>,
	"maarten.lankhorst@...ux.intel.com" <maarten.lankhorst@...ux.intel.com>,
	"mripard@...nel.org" <mripard@...nel.org>, "tzimmermann@...e.de"
	<tzimmermann@...e.de>, "robh+dt@...nel.org" <robh+dt@...nel.org>,
	"krzysztof.kozlowski+dt@...aro.org" <krzysztof.kozlowski+dt@...aro.org>,
	"conor+dt@...nel.org" <conor+dt@...nel.org>, "wahrenst@....net"
	<wahrenst@....net>, "dave.stevenson@...pberrypi.com"
	<dave.stevenson@...pberrypi.com>, "thierry.reding@...il.com"
	<thierry.reding@...il.com>, Changhuang Liang
	<changhuang.liang@...rfivetech.com>, Keith Zhao
	<keith.zhao@...rfivetech.com>, Jack Zhu <jack.zhu@...rfivetech.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 0/2] Add waveshare 7inch touchscreen panel support

Hi, Neil

> -----Original Message-----
> From: neil.armstrong@...aro.org <neil.armstrong@...aro.org>
> Sent: 2024年1月16日 17:34
> To: Shengyang Chen <shengyang.chen@...rfivetech.com>;
> devicetree@...r.kernel.org; dri-devel@...ts.freedesktop.org
> Cc: quic_jesszhan@...cinc.com; sam@...nborg.org; airlied@...il.com;
> daniel@...ll.ch; maarten.lankhorst@...ux.intel.com; mripard@...nel.org;
> tzimmermann@...e.de; robh+dt@...nel.org;
> krzysztof.kozlowski+dt@...aro.org; conor+dt@...nel.org; wahrenst@....net;
> dave.stevenson@...pberrypi.com; thierry.reding@...il.com; Changhuang
> Liang <changhuang.liang@...rfivetech.com>; Keith Zhao
> <keith.zhao@...rfivetech.com>; Jack Zhu <jack.zhu@...rfivetech.com>;
> linux-kernel@...r.kernel.org
> 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@...aro.org <neil.armstrong@...aro.org>
> >> Sent: 2024年1月9日 19:19
> >> To: Shengyang Chen <shengyang.chen@...rfivetech.com>;
> >> devicetree@...r.kernel.org; dri-devel@...ts.freedesktop.org
> >> Cc: quic_jesszhan@...cinc.com; sam@...nborg.org; airlied@...il.com;
> >> daniel@...ll.ch; maarten.lankhorst@...ux.intel.com;
> >> mripard@...nel.org; tzimmermann@...e.de; robh+dt@...nel.org;
> >> krzysztof.kozlowski+dt@...aro.org; conor+dt@...nel.org;
> >> wahrenst@....net; dave.stevenson@...pberrypi.com;
> >> thierry.reding@...il.com; Changhuang Liang
> >> <changhuang.liang@...rfivetech.com>; Keith Zhao
> >> <keith.zhao@...rfivetech.com>; Jack Zhu <jack.zhu@...rfivetech.com>;
> >> linux-kernel@...r.kernel.org
> >> 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@starfivetech.com/
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@...rfivetech.com/
> >>>
> >>> 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