linux-kernel - Re: [PATCH 11/17] drm: renesas: rz-du: mipi

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Message-ID: <CA+V-a8tVQaDBzLXVJUonmV6eW3i_KLTTjVm3L0Kf2A1xrMoUHQ@mail.gmail.com>
Date: Mon, 31 Mar 2025 14:44:08 +0000
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: Geert Uytterhoeven <geert+renesas@...der.be>, Andrzej Hajda <andrzej.hajda@...el.com>, 
	Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
	"laurent.pinchart" <laurent.pinchart@...asonboard.com>, Jonas Karlman <jonas@...boo.se>, 
	Jernej Skrabec <jernej.skrabec@...il.com>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>, 
	Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Mauro Carvalho Chehab <mchehab@...nel.org>, 
	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>, Stephen Boyd <sboyd@...nel.org>, 
	Philipp Zabel <p.zabel@...gutronix.de>, 
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>, 
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, 
	"linux-renesas-soc@...r.kernel.org" <linux-renesas-soc@...r.kernel.org>, 
	"linux-media@...r.kernel.org" <linux-media@...r.kernel.org>, 
	"linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>, 
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH 11/17] drm: renesas: rz-du: mipi_dsi: Add OF data support

Hi Biju,

On Mon, Mar 31, 2025 at 3:14 PM Biju Das <biju.das.jz@...renesas.com> wrote:
>
>
>
> > -----Original Message-----
> > From: Lad, Prabhakar <prabhakar.csengg@...il.com>
> > Sent: 31 March 2025 14:59
> > To: Biju Das <biju.das.jz@...renesas.com>
> > Cc: Geert Uytterhoeven <geert+renesas@...der.be>; Andrzej Hajda <andrzej.hajda@...el.com>; Neil
> > Armstrong <neil.armstrong@...aro.org>; Robert Foss <rfoss@...nel.org>; laurent.pinchart
> > <laurent.pinchart@...asonboard.com>; Jonas Karlman <jonas@...boo.se>; Jernej Skrabec
> > <jernej.skrabec@...il.com>; David Airlie <airlied@...il.com>; Simona Vetter <simona@...ll.ch>; Maarten
> > Lankhorst <maarten.lankhorst@...ux.intel.com>; Maxime Ripard <mripard@...nel.org>; Thomas Zimmermann
> > <tzimmermann@...e.de>; Rob Herring <robh@...nel.org>; Krzysztof Kozlowski <krzk+dt@...nel.org>; Conor
> > Dooley <conor+dt@...nel.org>; Mauro Carvalho Chehab <mchehab@...nel.org>; Kieran Bingham
> > <kieran.bingham+renesas@...asonboard.com>; Stephen Boyd <sboyd@...nel.org>; Philipp Zabel
> > <p.zabel@...gutronix.de>; devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; linux-renesas-
> > soc@...r.kernel.org; linux-media@...r.kernel.org; linux-clk@...r.kernel.org; Fabrizio Castro
> > <fabrizio.castro.jz@...esas.com>; Prabhakar Mahadev Lad <prabhakar.mahadev-lad.rj@...renesas.com>
> > Subject: Re: [PATCH 11/17] drm: renesas: rz-du: mipi_dsi: Add OF data support
> >
> > Hi Biju,
> >
> > Thank you for the review.
> >
> > On Mon, Mar 31, 2025 at 1:38 PM Biju Das <biju.das.jz@...renesas.com> wrote:
> > >
> > > Hi Prabhakar,
> > >
> > > Thanks for the patch.
> > >
> > > > -----Original Message-----
> > > > From: Prabhakar <prabhakar.csengg@...il.com>
> > > > Sent: 30 March 2025 22:07
> > > > Subject: [PATCH 11/17] drm: renesas: rz-du: mipi_dsi: Add OF data
> > > > support
> > > >
> > > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > > >
> > > > In preparation for adding support for the Renesas RZ/V2H(P) SoC,
> > > > this patch introduces a mechanism to pass SoC-specific information
> > > > via OF data in the DSI driver. This enables the driver to adapt dynamically to various SoC-
> > specific requirements without hardcoding configurations.
> > > >
> > > > The MIPI DSI interface on the RZ/V2H(P) SoC is nearly identical to
> > > > the one on the RZ/G2L SoC. While the LINK registers are shared
> > > > between the two SoCs, the D-PHY registers differ. Also the VCLK
> > > > range differs on both these SoCs. To accommodate these differences `struct rzg2l_mipi_dsi_hw_info`
> > is introduced and as now passed as OF data.
> > > >
> > > > These changes lay the groundwork for the upcoming RZ/V2H(P) SoC
> > > > support by allowing SoC-specific data to be passed through OF.
> > > >
> > <snip>
> > > > +
> > > >       ret = drm_of_get_data_lanes_count_ep(dsi->dev->of_node, 1, 0, 1, 4);
> > > >       if (ret < 0)
> > > >               return dev_err_probe(dsi->dev, ret, @@ -729,10 +750,12
> > > > @@ static int rzg2l_mipi_dsi_probe(struct platform_device *pdev)
> > > >       if (IS_ERR(dsi->vclk))
> > > >               return PTR_ERR(dsi->vclk);
> > > >
> > > > -     dsi->rstc = devm_reset_control_get_exclusive(dsi->dev, "rst");
> > > > -     if (IS_ERR(dsi->rstc))
> > > > -             return dev_err_probe(dsi->dev, PTR_ERR(dsi->rstc),
> > > > -                                  "failed to get rst\n");
> > > > +     if (dsi->info->has_dphy_rstc) {
> > > > +             dsi->rstc = devm_reset_control_get_exclusive(dsi->dev,
> > > > + "rst");
> > >
> > > Maybe use devm_reset_control_get_optional_exclusive by dropping has_dphy_rstc.
> > >
> > As the dtbs_check doesn't enforce this,  `has_dphy_rstc` flag was added. Recently the same was done
> > for the CRU [0] based on the recent comment received.
> >
>
> RZ/V2H has "arst" and "prst". So, If you add "rst" for RZ/V2H then you should get dtbs warning, right?
>
No we dont [0], note DT binding is written based on the recent
feedback received.

[0] https://patchwork.kernel.org/project/linux-renesas-soc/patch/20250330210717.46080-7-prabhakar.mahadev-lad.rj@bp.renesas.com/

Cheers,
Prabhakar