[PATCH v2 14/15] drm: renesas: rz-du: mipi_dsi: Add support for LPCLK handling

[Prabhakar]

From: Lad Prabhakar <prabhakar.mahadev-lad.rj at 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.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:
- 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 a9dad3b1974f..6c6bc59eabbc 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;
@@ -791,6 +793,12 @@ 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