linux-kernel - Re: [PATCH v5 09/12] drm: renesas: rz-du: mipi

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Message-ID: <20250520142602.GH13321@pendragon.ideasonboard.com>
Date: Tue, 20 May 2025 16:26:02 +0200
From: Laurent Pinchart <laurent.pinchart@...asonboard.com>
To: Prabhakar <prabhakar.csengg@...il.com>
Cc: Biju Das <biju.das.jz@...renesas.com>, David Airlie <airlied@...il.com>,
	Simona Vetter <simona@...ll.ch>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	Magnus Damm <magnus.damm@...il.com>,
	dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	Fabrizio Castro <fabrizio.castro.jz@...esas.com>,
	Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
Subject: Re: [PATCH v5 09/12] drm: renesas: rz-du: mipi_dsi: Add feature flag
 for 16BPP support

Hi Prabhakar,

Thank you for the patch.

On Mon, May 12, 2025 at 07:23:27PM +0100, Prabhakar wrote:
> From: Lad Prabhakar <prabhakar.mahadev-lad.rj@...renesas.com>
> 
> Introduce the `RZ_MIPI_DSI_FEATURE_16BPP` flag in `rzg2l_mipi_dsi_hw_info`
> to indicate support for 16BPP pixel formats. The RZ/V2H(P) SoC supports
> 16BPP, whereas this feature is missing on the RZ/G2L SoC.
> 
> Update the `mipi_dsi_host_attach()` function to check this flag before
> allowing 16BPP formats. If the SoC does not support 16BPP, return an error
> to prevent incorrect format selection.
> 
> This change enables finer-grained format support control for different
> SoC variants.
> 
> 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: Biju Das <biju.das.jz@...renesas.com>

Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>

> ---
> v4->v5:
> - Updated RZ_MIPI_DSI_FEATURE_16BPP macro to use BIT(0)
> - Added Reviewed tag from Biju
> 
> v3->v4:
> - No changes
> 
> v2->v3:
> - No changes
> 
> v1->v2:
> - Renamed RZ_MIPI_DSI_FEATURE_16BPP
> ---
>  drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 11 +++++++++++
>  1 file changed, 11 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 f93519613662..55a1c1b043c8 100644
> --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
> @@ -28,6 +28,8 @@
>  
>  #include "rzg2l_mipi_dsi_regs.h"
>  
> +#define RZ_MIPI_DSI_FEATURE_16BPP	BIT(0)
> +
>  struct rzg2l_mipi_dsi;
>  
>  struct rzg2l_mipi_dsi_hw_info {
> @@ -37,6 +39,7 @@ struct rzg2l_mipi_dsi_hw_info {
>  	u32 link_reg_offset;
>  	unsigned long max_dclk;
>  	unsigned long min_dclk;
> +	u8 features;
>  };
>  
>  struct rzg2l_mipi_dsi {
> @@ -643,8 +646,16 @@ static int rzg2l_mipi_dsi_host_attach(struct mipi_dsi_host *host,
>  
>  	switch (mipi_dsi_pixel_format_to_bpp(device->format)) {
>  	case 24:
> +		break;
>  	case 18:
>  		break;
> +	case 16:
> +		if (!(dsi->info->features & RZ_MIPI_DSI_FEATURE_16BPP)) {
> +			dev_err(dsi->dev, "Unsupported format 0x%04x\n",
> +				device->format);
> +			return -EINVAL;
> +		}
> +		break;
>  	default:
>  		dev_err(dsi->dev, "Unsupported format 0x%04x\n", device->format);
>  		return -EINVAL;

-- 
Regards,

Laurent Pinchart