[PATCH 2/4] drm/panel: ilitek-ili9881c: Add support for two-lane configuration

[Kory Maincent]

Enable support for two-lane configuration which is done by setting the
LANSEL_SW_EN and LANSEL_SW bits in the Pad Control register.

Use the dsi-lanes device tree parameter to configure the number of lanes.
The default configuration remains set to four lanes.

Signed-off-by: Kory Maincent <kory.mainc...@bootlin.com>
---
 drivers/gpu/drm/panel/panel-ilitek-ili9881c.c | 35 +++++++++++++++++++++++++--
 1 file changed, 33 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/panel/panel-ilitek-ili9881c.c 
b/drivers/gpu/drm/panel/panel-ilitek-ili9881c.c
index 
28cd7560e5db1d5734b10babdb4e4e553c6e07d0..5c429715159755df2461063dad0971642e2b9041
 100644
--- a/drivers/gpu/drm/panel/panel-ilitek-ili9881c.c
+++ b/drivers/gpu/drm/panel/panel-ilitek-ili9881c.c
@@ -1263,6 +1263,21 @@ static int ili9881c_send_cmd_data(struct ili9881c *ctx, 
u8 cmd, u8 data)
        return 0;
 }
 
+static int ili9881c_set_lanes_cfg(struct ili9881c *ctx)
+{
+       int ret;
+
+       if (ctx->dsi->lanes != 2)
+               /* Nothing to do */
+               return 0;
+
+       ret = ili9881c_switch_page(ctx, 1);
+       if (ret)
+               return ret;
+
+       return ili9881c_send_cmd_data(ctx, 0xB7, 0x3);
+}
+
 static int ili9881c_prepare(struct drm_panel *panel)
 {
        struct ili9881c *ctx = panel_to_ili9881c(panel);
@@ -1295,6 +1310,10 @@ static int ili9881c_prepare(struct drm_panel *panel)
                        return ret;
        }
 
+       ret = ili9881c_set_lanes_cfg(ctx);
+       if (ret)
+               return ret;
+
        ret = ili9881c_switch_page(ctx, 0);
        if (ret)
                return ret;
@@ -1504,7 +1523,7 @@ static const struct drm_panel_funcs ili9881c_funcs = {
 static int ili9881c_dsi_probe(struct mipi_dsi_device *dsi)
 {
        struct ili9881c *ctx;
-       int ret;
+       int ret, lanes;
 
        ctx = devm_kzalloc(&dsi->dev, sizeof(*ctx), GFP_KERNEL);
        if (!ctx)
@@ -1545,11 +1564,23 @@ static int ili9881c_dsi_probe(struct mipi_dsi_device 
*dsi)
        if (ret)
                return ret;
 
+       ret = of_property_read_u32(dsi->dev.of_node, "dsi-lanes", &lanes);
+       if (ret == -EINVAL) {
+               lanes = 4;
+       } else if (ret) {
+               dev_err(&dsi->dev, "Failed to get dsi-lanes property (%d)\n",
+                       ret);
+               return ret;
+       } else if (lanes < 2 || 4 < lanes) {
+               dev_err(&dsi->dev, "Wrong number of dsi-lanes (%d)\n", lanes);
+               return -EINVAL;
+       }
+
        drm_panel_add(&ctx->panel);
 
        dsi->mode_flags = ctx->desc->mode_flags;
        dsi->format = MIPI_DSI_FMT_RGB888;
-       dsi->lanes = 4;
+       dsi->lanes = lanes;
 
        return mipi_dsi_attach(dsi);
 }

-- 
2.34.1