[PATCH v7 7/9] drm: renesas: rz-du: mipi_dsi: Add feature flag for 16BPP support

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>

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@xxxxxxxxxxx>
Signed-off-by: Fabrizio Castro <fabrizio.castro.jz@xxxxxxxxxxx>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
Reviewed-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
Reviewed-by: Laurent Pinchart <laurent.pinchart+renesas@xxxxxxxxxxxxxxxx>
---
v6->v7:
- No changes

v5->v6:
- Added Reviewed-by tag from Laurent

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 004911240cef..afb427e678bd 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -34,6 +34,8 @@
 
 #define RZG2L_DCS_BUF_SIZE	128 /* Maximum DCS buffer size in external memory. */
 
+#define RZ_MIPI_DSI_FEATURE_16BPP	BIT(0)
+
 struct rzg2l_mipi_dsi;
 
 struct rzg2l_mipi_dsi_hw_info {
@@ -43,6 +45,7 @@ struct rzg2l_mipi_dsi_hw_info {
 	u32 link_reg_offset;
 	unsigned long min_dclk;
 	unsigned long max_dclk;
+	u8 features;
 };
 
 struct rzg2l_mipi_dsi {
@@ -672,8 +675,16 @@ 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