[PATCH v4 14/15] drm: renesas: rz-du: mipi_dsi: Add support for LPCLK handling

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad...@bp.renesas.com>

Introduce the `RZ_MIPI_DSI_FEATURE_LPCLK` feature flag in
`rzg2l_mipi_dsi_hw_info` to indicate the need for LPCLK configuration.

On the RZ/V2H(P) SoC, the LPCLK clock rate influences the required
DPHY register configuration, whereas on the RZ/G2L SoC, this clock
is not present. To accommodate this difference, add an `lpclk`
clock handle in `rzg2l_mipi_dsi` and update the probe function to
conditionally acquire LPCLK if the SoC supports it.

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:
- Added LPCLK as feature flag
---
 drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c | 8 ++++++++
 1 file changed, 8 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 df43ff59e08e..22a386ca8ae3 100644
--- a/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
+++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_mipi_dsi.c
@@ -30,6 +30,7 @@
 
 #define RZ_MIPI_DSI_FEATURE_DPHY_RST   BIT(0)
 #define RZ_MIPI_DSI_FEATURE_16BPP      BIT(1)
+#define RZ_MIPI_DSI_FEATURE_LPCLK      BIT(2)
 
 struct rzg2l_mipi_dsi;
 
@@ -63,6 +64,7 @@ struct rzg2l_mipi_dsi {
        struct drm_bridge *next_bridge;
 
        struct clk *vclk;
+       struct clk *lpclk;
 
        enum mipi_dsi_pixel_format format;
        unsigned int num_data_lanes;
@@ -788,6 +790,12 @@ static int rzg2l_mipi_dsi_probe(struct platform_device 
*pdev)
        if (IS_ERR(dsi->vclk))
                return PTR_ERR(dsi->vclk);
 
+       if (dsi->info->features & RZ_MIPI_DSI_FEATURE_LPCLK) {
+               dsi->lpclk = devm_clk_get(dsi->dev, "lpclk");
+               if (IS_ERR(dsi->lpclk))
+                       return PTR_ERR(dsi->lpclk);
+       }
+
        if (dsi->info->features & RZ_MIPI_DSI_FEATURE_DPHY_RST) {
                dsi->rstc = devm_reset_control_get_exclusive(dsi->dev, "rst");
                if (IS_ERR(dsi->rstc))
-- 
2.49.0