[PATCH v4 11/15] drm: renesas: rz-du: mipi_dsi: Add feature flag for 16BPP support

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad...@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...@renesas.com>
Signed-off-by: Fabrizio Castro <fabrizio.castro...@renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad...@bp.renesas.com>
---
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 | 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 a4c0dbae4a46..8c7384b95411 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