Re: [PATCH 11/17] drm: renesas: rz-du: mipi_dsi: Add OF data support

Lad, Prabhakar
2025-03-31T15:27:49Z

Hi Biju,

On Mon, Mar 31, 2025 at 4:04 PM Biju Das <biju.das.jz@bp.renesas.com> wrote:
>
> Hi Prabhakar,
>
> > -----Original Message-----
> > From: Lad, Prabhakar <prabhakar.csengg@gmail.com>
> > Sent: 31 March 2025 15:44
> > 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@bp.renesas.com> wrote:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Lad, Prabhakar <prabhakar.csengg@gmail.com>
> > > > Sent: 31 March 2025 14:59
> > > > To: Biju Das <biju.das.jz@bp.renesas.com>
> > > > Cc: Geert Uytterhoeven <geert+renesas@glider.be>; Andrzej Hajda
> > > > <andrzej.hajda@intel.com>; Neil Armstrong
> > > > <neil.armstrong@linaro.org>; Robert Foss <rfoss@kernel.org>;
> > > > laurent.pinchart <laurent.pinchart@ideasonboard.com>; Jonas Karlman
> > > > <jonas@kwiboo.se>; Jernej Skrabec <jernej.skrabec@gmail.com>; David
> > > > Airlie <airlied@gmail.com>; Simona Vetter <simona@ffwll.ch>; Maarten
> > > > Lankhorst <maarten.lankhorst@linux.intel.com>; Maxime Ripard
> > > > <mripard@kernel.org>; Thomas Zimmermann <tzimmermann@suse.de>; Rob
> > > > Herring <robh@kernel.org>; Krzysztof Kozlowski <krzk+dt@kernel.org>;
> > > > Conor Dooley <conor+dt@kernel.org>; Mauro Carvalho Chehab
> > > > <mchehab@kernel.org>; Kieran Bingham
> > > > <kieran.bingham+renesas@ideasonboard.com>; Stephen Boyd
> > > > <sboyd@kernel.org>; Philipp Zabel <p.zabel@pengutronix.de>;
> > > > devicetree@vger.kernel.org; linux-kernel@vger.kernel.org;
> > > > linux-renesas- soc@vger.kernel.org; linux-media@vger.kernel.org;
> > > > linux-clk@vger.kernel.org; Fabrizio Castro
> > > > <fabrizio.castro.jz@renesas.com>; Prabhakar Mahadev Lad
> > > > <prabhakar.mahadev-lad.rj@bp.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@bp.renesas.com> wrote:
> > > > >
> > > > > Hi Prabhakar,
> > > > >
> > > > > Thanks for the patch.
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: Prabhakar <prabhakar.csengg@gmail.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@bp.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.
>
> That is strange. It is triggering warning for me, if I just update the example.
>
Ahh right I missed that. The current implementation is based on this
comment received [0] (same being applied for reset). Please let me
know if you still want me to use
devm_reset_control_get_optional_exclusive() (and same for the clk).

[0] https://lore.kernel.org/lkml/20250223181955.GD8330@pendragon.ideasonboard.com/

Cheers,
Prabhakar