linux-kernel - Re: [PATCH v4 14/15] drm: renesas: rz-du: mipi

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Message-ID: <CA+V-a8vz-7o96s0ok2ap+Kg2=BKMv8O8Zk667bYi+0Cu8F399Q@mail.gmail.com>
Date: Mon, 12 May 2025 16:58:05 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Biju Das <biju.das.jz@...renesas.com>
Cc: 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>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Michael Turquette <mturquette@...libre.com>, 
	Stephen Boyd <sboyd@...nel.org>, Philipp Zabel <p.zabel@...gutronix.de>, 
	Magnus Damm <magnus.damm@...il.com>, 
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>, 
	"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-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 v4 14/15] drm: renesas: rz-du: mipi_dsi: Add support for
 LPCLK handling

Hi Biju,

Thank you for the review.

On Sun, May 4, 2025 at 2:00 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 April 2025 21:41
> > Subject: [PATCH v4 14/15] drm: renesas: rz-du: mipi_dsi: Add support for LPCLK handling
> >
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Introduce the `RZ_MIPI_DSI_FEATURE_LPCLK` feature flag in `rzg2l_mipi_dsi_hw_info` to indicate the
> > need for LPCLK configuration.
> >
> > On the RZ/V2H(P) SoC, the LPCLK clock rate influences the required DPHY register configuration,
> > whereas on the RZ/G2L SoC, this clock is not present. To accommodate this difference, add an `lpclk`
> > clock handle in `rzg2l_mipi_dsi` and update the probe function to conditionally acquire LPCLK if the
> > SoC supports it.
> >
> > Co-developed-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> > Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@...esas.com>
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> > ---
> > v3->v4
> > - No changes
> >
> > v2->v3:
> > - No changes
> >
> > v1->v2:
> > - Added LPCLK as feature flag
> > ---
> >  drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c b/drivers/gpu/drm/renesas/rz-
> > du/rzg2l_mipi_dsi.c
> > index df43ff59e08e..22a386ca8ae3 100644
> > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> > @@ -30,6 +30,7 @@
> >
> >  #define RZ_MIPI_DSI_FEATURE_DPHY_RST BIT(0)
> >  #define RZ_MIPI_DSI_FEATURE_16BPP    BIT(1)
> > +#define RZ_MIPI_DSI_FEATURE_LPCLK    BIT(2)
> >
> >  struct rzg2l_mipi_dsi;
> >
> > @@ -63,6 +64,7 @@ struct rzg2l_mipi_dsi {
> >       struct drm_bridge *next_bridge;
> >
> >       struct clk *vclk;
> > +     struct clk *lpclk;
> >
> >       enum mipi_dsi_pixel_format format;
> >       unsigned int num_data_lanes;
> > @@ -788,6 +790,12 @@ static int rzg2l_mipi_dsi_probe(struct platform_device *pdev)
> >       if (IS_ERR(dsi->vclk))
> >               return PTR_ERR(dsi->vclk);
> >
> > +     if (dsi->info->features & RZ_MIPI_DSI_FEATURE_LPCLK) {
> > +             dsi->lpclk = devm_clk_get(dsi->dev, "lpclk");
> > +             if (IS_ERR(dsi->lpclk))
> > +                     return PTR_ERR(dsi->lpclk);
> > +     }
> > +
>
> Can we use devm_clk_get_optional() and get rid of this Feature bit check
> as DT binding check validates for a particular SoC this clk is required or not?
> Otherwise, there is no usage for optional API's?
>
OK, I'll switch to devm_clk_get_optional().

Cheers,
Prabhakar