video: tegra: refuse to bind to disabled dcs

This prevents the following boot-time message on any board where only the
first DC is in use, yet the DC's DT node is enabled:

stdio_add_devices: Video device failed (ret=-22)

(This happens on at least Harmony, Ventana, and likely any other Tegra20
board with display enabled other than Seaboard).

The Tegra DC's DT node represents a display controller. It may itself
drive an integrated RGB display output, or be used by some other display
controller such as HDMI. For this reason the DC node itself is not
enabled/disabled in DT; the DC itself is considered a shared resource, not
the final (board-specific) display output. The node should instantiate a
display output driver only if the rgb subnode is enabled. Other output
drivers are free to use the DC if they are enabled and their DT node
references the DC's DT node. Adapt the Tegra display drivers' bind()
routine to only bind to the DC's DT node if the RGB subnode is enabled.

Now that the display driver does the right thing, remove the workaround
for this issue from Seaboard's DT file.

Cc: Thierry Reding <treding@nvidia.com>
Signed-off-by: Stephen Warren <swarren@nvidia.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

diff --git a/arch/arm/dts/tegra20-seaboard.dts b/arch/arm/dts/tegra20-seaboard.dts
index eada59073efcfd8d41f70e1010a30496ac04b5e0..5893d2a3f84e67ad68d21ab108e442873011710c 100644 (file)
--- a/arch/arm/dts/tegra20-seaboard.dts
+++ b/arch/arm/dts/tegra20-seaboard.dts
@@ -40,10 +40,6 @@
                                nvidia,panel = <&lcd_panel>;
                        };
                };
-
-               dc@54240000 {
-                       status = "disabled";
-               };
        };
 
        /* This is not used in U-Boot, but is expected to be in kernel .dts */

diff --git a/drivers/video/tegra.c b/drivers/video/tegra.c
index 7fd10e6af35e9b80f624c6f6aec04ffb906e1e1f..c01809e89e142a0de3a3b609e478e55c19f03bbb 100644 (file)
--- a/drivers/video/tegra.c
+++ b/drivers/video/tegra.c
@@ -620,6 +620,13 @@ static int tegra_lcd_ofdata_to_platdata(struct udevice *dev)
 static int tegra_lcd_bind(struct udevice *dev)
 {
        struct video_uc_platdata *plat = dev_get_uclass_platdata(dev);
+       const void *blob = gd->fdt_blob;
+       int node = dev->of_offset;
+       int rgb;
+
+       rgb = fdt_subnode_offset(blob, node, "rgb");
+       if ((rgb < 0) || !fdtdec_get_is_enabled(blob, rgb))
+               return -ENODEV;
 
        plat->size = LCD_MAX_WIDTH * LCD_MAX_HEIGHT *
                (1 << LCD_MAX_LOG2_BPP) / 8;