Adds support for limitation of maximal pixel clock of HDMI
signal. This feature is needed on boards that contains
lines or bridges with frequency limitations.
Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
---
.../devicetree/bindings/video/exynos_hdmi.txt | 4 ++++
drivers/gpu/drm/exynos/exynos_hdmi.c | 11 +++++++++++
2 files changed, 15 insertions(+)
diff --git a/Documentation/devicetree/bindings/video/exynos_hdmi.txt b/Documentation/devicetree/bindings/video/exynos_hdmi.txt
index f9187a2..8718f8d 100644
--- a/Documentation/devicetree/bindings/video/exynos_hdmi.txt
+++ b/Documentation/devicetree/bindings/video/exynos_hdmi.txt
@@ -28,6 +28,10 @@ Required properties:
- ddc: phandle to the hdmi ddc node
- phy: phandle to the hdmi phy node
+Optional properties:
+- max-pixel-clock: used to limit the maximal pixel clock if a board has lines,
+ connectors or bridges not capable of carring higher frequencies
+
Example:
hdmi {
diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
index 9adbd34..e012ba9 100644
--- a/drivers/gpu/drm/exynos/exynos_hdmi.c
+++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
@@ -194,6 +194,7 @@ struct hdmi_context {
struct hdmi_resources res;
int hpd_gpio;
+ u32 max_pixel_clock;
enum hdmi_type type;
};
@@ -886,6 +887,9 @@ static int hdmi_mode_valid(struct drm_connector *connector,
if (ret)
return MODE_BAD;
+ if (mode->clock * 1000 > hdata->max_pixel_clock)
+ return MODE_CLOCK_HIGH;
+
ret = hdmi_find_phy_conf(hdata, mode->clock * 1000);
if (ret < 0)
return MODE_BAD;
@@ -2022,6 +2026,13 @@ static int drm_hdmi_dt_parse(struct hdmi_context *hdata, struct device_node *np)
return -ENOENT;
}
+ of_property_read_u32(np, "max-pixel-clock", &hdata->max_pixel_clock);
+ if (!hdata->max_pixel_clock) {
+ DRM_INFO("max-pixel-clock is zero, using INF\n");
+ hdata->max_pixel_clock = U32_MAX;
+ }
+
+
return 0;
}
--
1.7.9.5
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