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

[Biju Das]

Hi Prabhakar,

> -----Original Message-----
> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> Sent: 31 March 2025 16:27
> Subject: Re: [PATCH 11/17] drm: renesas: rz-du: mipi_dsi: Add OF data support
> 
> Hi Biju,
> 
> On Mon, Mar 31, 2025 at 4:04 PM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Prabhakar,
> >
> > > -----Original Message-----
> > > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > 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@xxxxxxxxxxxxxx> wrote:
> > > >
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > > > Sent: 31 March 2025 14:59
> > > > > To: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
> > > > > Cc: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>; Andrzej Hajda
> > > > > <andrzej.hajda@xxxxxxxxx>; Neil Armstrong
> > > > > <neil.armstrong@xxxxxxxxxx>; Robert Foss <rfoss@xxxxxxxxxx>;
> > > > > laurent.pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>; Jonas
> > > > > Karlman <jonas@xxxxxxxxx>; Jernej Skrabec
> > > > > <jernej.skrabec@xxxxxxxxx>; David Airlie <airlied@xxxxxxxxx>;
> > > > > Simona Vetter <simona@xxxxxxxx>; Maarten Lankhorst
> > > > > <maarten.lankhorst@xxxxxxxxxxxxxxx>; Maxime Ripard
> > > > > <mripard@xxxxxxxxxx>; Thomas Zimmermann <tzimmermann@xxxxxxx>;
> > > > > Rob Herring <robh@xxxxxxxxxx>; Krzysztof Kozlowski
> > > > > <krzk+dt@xxxxxxxxxx>; Conor Dooley <conor+dt@xxxxxxxxxx>; Mauro
> > > > > Carvalho Chehab <mchehab@xxxxxxxxxx>; Kieran Bingham
> > > > > <kieran.bingham+renesas@xxxxxxxxxxxxxxxx>; Stephen Boyd
> > > > > <sboyd@xxxxxxxxxx>; Philipp Zabel <p.zabel@xxxxxxxxxxxxxx>;
> > > > > devicetree@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> > > > > linux-renesas- soc@xxxxxxxxxxxxxxx; linux-media@xxxxxxxxxxxxxxx;
> > > > > linux-clk@xxxxxxxxxxxxxxx; Fabrizio Castro
> > > > > <fabrizio.castro.jz@xxxxxxxxxxx>; Prabhakar Mahadev Lad
> > > > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > > > 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@xxxxxxxxxxxxxx> wrote:
> > > > > >
> > > > > > Hi Prabhakar,
> > > > > >
> > > > > > Thanks for the patch.
> > > > > >
> > > > > > > -----Original Message-----
> > > > > > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > > > > > 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@xxxxxxxxxxxxxx>
> > > > > > >
> > > > > > > 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).

Both OK to me. As DT binding validates optional resets, I would avoid redundant check in
driver as it is anyway like no-op with optional calls.

Cheers,
Biju