Re: [PATCH v3 07/13] drm: renesas: rz-du: Add support for RZ/G3L LVDS encoder

[Philipp Zabel <p.zabel@pengutronix.de>]

On Mi, 2026-08-26 at 18:48 +0100, Biju wrote:
> From: Biju Das <biju.das.jz@bp.renesas.com>
> 
> Add support for the RZ/G3L LVDS encoder driver. It operates in single-link
> mode with 4 lanes (Data) + 1 lane (Clock) and supports pixel clock rates
> from 25 to 87 MHz. The LVDS module cannot be used at the same time as
> MIPI-DSI. However, LVDS and the DSI interface share a peripheral clock and
> the MIPI_DSI_PRESET_N reset signal. Also, the MIPI_DSI_CMN_RSTB and
> MIPI_DSI_ARESET_N reset signals must be asserted before using the LVDS
> module.
> 
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> Tested-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> Reviewed-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
[...]
> ---
>  drivers/gpu/drm/renesas/rz-du/Kconfig         |  13 +
>  drivers/gpu/drm/renesas/rz-du/Makefile        |   1 +
>  drivers/gpu/drm/renesas/rz-du/rzg3l_lvds.c    | 295 ++++++++++++++++++
>  .../gpu/drm/renesas/rz-du/rzg3l_lvds_regs.h   |  25 ++
>  4 files changed, 334 insertions(+)
>  create mode 100644 drivers/gpu/drm/renesas/rz-du/rzg3l_lvds.c
>  create mode 100644 drivers/gpu/drm/renesas/rz-du/rzg3l_lvds_regs.h
> 
[...]
> diff --git a/drivers/gpu/drm/renesas/rz-du/rzg3l_lvds.c b/drivers/gpu/drm/renesas/rz-du/rzg3l_lvds.c
> new file mode 100644
> index 000000000000..2a7ae67ff08d
> --- /dev/null
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg3l_lvds.c
> @@ -0,0 +1,295 @@
[...]
> +static int rzg3l_lvds_probe(struct platform_device *pdev)
> +{
> +	struct reset_control *rstc, *arstc;
> +	struct device *dev = &pdev->dev;
> +	struct rzg3l_lvds *lvds;
> +	void __iomem *base;
> +	int ret;
> +
> +	lvds = devm_drm_bridge_alloc(dev, struct rzg3l_lvds, bridge,
> +				     &rzg3l_lvds_bridge_ops);
> +	if (IS_ERR(lvds))
> +		return PTR_ERR(lvds);
> +
> +	lvds->dev = dev;
> +	lvds->bridge.of_node = pdev->dev.of_node;
> +
> +	base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(base))
> +		return PTR_ERR(base);
> +
> +	lvds->regmap = devm_regmap_init_mmio(dev, base, &rzg3l_lvds_regmap_config);
> +	if (IS_ERR(lvds->regmap))
> +		return dev_err_probe(dev, PTR_ERR(lvds->regmap),
> +				     "failed to init regmap\n");
> +
> +	lvds->dotclk = devm_clk_get(dev, "dotclk");
> +	if (IS_ERR(lvds->dotclk))
> +		return PTR_ERR(lvds->dotclk);
> +
> +	rstc = devm_reset_control_get_exclusive(dev, "rst");
> +	if (IS_ERR(rstc))
> +		return dev_err_probe(dev, PTR_ERR(rstc), "failed to get rst\n");
> +
> +	arstc = devm_reset_control_get_exclusive(dev, "arst");
> +	if (IS_ERR(arstc))
> +		return dev_err_probe(dev, PTR_ERR(arstc),
> +				     "failed to get arst\n");

It would be nice to have a comment about the two MIPI DSI resets having
to be asserted here as well.

Also, it looks like you could pair these two ...

> +
> +	lvds->prstc = devm_reset_control_get_exclusive(dev, "prst");
> +	if (IS_ERR(lvds->prstc))
> +		return dev_err_probe(dev, PTR_ERR(lvds->prstc),
> +				     "failed to get prst\n");
> +
> +	lvds->lvd_rstc = devm_reset_control_get_exclusive(dev, "lvdrst");
> +	if (IS_ERR(lvds->lvd_rstc))
> +		return dev_err_probe(dev, PTR_ERR(lvds->lvd_rstc),
> +				     "failed to get core reset\n");

... and these two into a devm_reset_control_bulk_get_exclusive() each.

regards
Philipp