linux-kernel - Re: [PATCH v9 6/6] drm: renesas: rz-du: mipi

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Message-ID: <CA+V-a8t7AQH5LpJaMgq9FUnA6qiUH=d5ngp0qr523BUWu88d+A@mail.gmail.com>
Date: Thu, 9 Oct 2025 14:03:06 +0100
From: "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To: Geert Uytterhoeven <geert@...ux-m68k.org>
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>, 
	Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
	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>, 
	Michael Turquette <mturquette@...libre.com>, Stephen Boyd <sboyd@...nel.org>, 
	Biju Das <biju.das.jz@...renesas.com>, Magnus Damm <magnus.damm@...il.com>, 
	dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-renesas-soc@...r.kernel.org, 
	linux-clk@...r.kernel.org, Fabrizio Castro <fabrizio.castro.jz@...esas.com>, 
	Tommaso Merciai <tommaso.merciai.xr@...renesas.com>, 
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v9 6/6] drm: renesas: rz-du: mipi_dsi: Add support for
 RZ/V2H(P) SoC

Hi Geert,

Thank you for the review.

On Mon, Oct 6, 2025 at 1:49 PM Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>
> Hi Prabhakar,
>
> On Thu, 2 Oct 2025 at 18:17, Prabhakar <prabhakar.csengg@...il.com> wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> >
> > Add MIPI DSI support for the Renesas RZ/V2H(P) SoC. Compared to the
> > RZ/G2L family, the RZ/V2H(P) requires dedicated D-PHY PLL programming,
> > different clock configuration, and additional timing parameter handling.
> > The driver introduces lookup tables and helpers for D-PHY timings
> > (TCLK*, THS*, TLPX, and ULPS exit) as specified in the RZ/V2H(P) hardware
> > manual. ULPS exit timing depends on the LPCLK rate and is now handled
> > explicitly.
> >
> > The implementation also adds support for 16 bpp RGB format, updates the
> > clock setup path to use the RZ/V2H PLL divider limits, and provides new
> > .dphy_init, .dphy_conf_clks, and .dphy_startup_late_init callbacks to
> > match the RZ/V2H sequence.
> >
> > With these changes, the RZ/V2H(P) can operate the MIPI DSI interface in
> > compliance with its hardware specification while retaining support for
> > existing RZ/G2L platforms.
> >
> > 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>
> > Reviewed-by: Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>
> > ---
> > v8->v9:
> > - Updated Kconfig to select CLK_RZV2H
> > - Updated to use renesas.h
> > - Added reviewed-by tag from Tomi
>
> Thanks for the update!
>
> > --- a/drivers/gpu/drm/renesas/rz-du/Kconfig
> > +++ b/drivers/gpu/drm/renesas/rz-du/Kconfig
> > @@ -19,6 +19,7 @@ config DRM_RZG2L_USE_MIPI_DSI
> >         depends on DRM_BRIDGE && OF
> >         depends on DRM_RZG2L_DU || COMPILE_TEST
> >         default DRM_RZG2L_DU
> > +       select CLK_RZV2H
>
> As the kernel test robot has already told you, this is not a good idea.
> RZ/V2H support is optional, just rely on (dummy) rzv2h_get_pll_*()
> helpers returning false if CLK_RZV2H is not enabled.
>
Agreed, I will add static inline helpers in renesas.h if !CLK_RZV2H.

Cheers,
Prabhakar

> >         help
> >           Enable support for the RZ/G2L Display Unit embedded MIPI DSI encoders.
> >
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>