[PATCH v2 11/15] drm: renesas: rz-du: mipi_dsi: Add feature flag for 16BPP support

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.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 at renesas.com>
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz at renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj at bp.renesas.com>
---
v1->v2:
- Renamed RZ_MIPI_DSI_FEATURE_16BPP
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 9 +++++++++
 1 file changed, 9 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 4a8fe52e9752..c8be7428c4d7 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -29,6 +29,7 @@
 #include "rzg2l_mipi_dsi_regs.h"
 
 #define RZ_MIPI_DSI_FEATURE_DPHY_RST	BIT(0)
+#define RZ_MIPI_DSI_FEATURE_16BPP	BIT(1)
 
 struct rzg2l_mipi_dsi;
 
@@ -643,8 +644,16 @@ 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;
-- 
2.49.0