From: Thierry Reding <treding@xxxxxxxxxx>
The display architecture on Tegra186 and Tegra194 requires that there be
some valid clock on all domains before accessing any display register. A
further requirement is that in addition to the host1x, hub, disp and dsc
clocks, all the head clocks (pclk0-2 on Tegra186 or pclk0-3 on Tegra194)
must also be enabled.
Implement this logic within the display hub driver to ensure the clocks
are always enabled at the right time.
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
Changes in v2:
- reverse order in which clocks are disabled for symmetry
- don't leak child device tree node
drivers/gpu/drm/tegra/hub.c | 48 +++++++++++++++++++++++++++++++++++--
drivers/gpu/drm/tegra/hub.h | 3 +++
2 files changed, 49 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/tegra/hub.c b/drivers/gpu/drm/tegra/hub.c
index 6112d9042979..922a48d5a483 100644
--- a/drivers/gpu/drm/tegra/hub.c
+++ b/drivers/gpu/drm/tegra/hub.c
@@ -742,7 +742,9 @@ static const struct host1x_client_ops tegra_display_hub_ops = {
static int tegra_display_hub_probe(struct platform_device *pdev)
{
+ struct device_node *child = NULL;
struct tegra_display_hub *hub;
+ struct clk *clk;
unsigned int i;
int err;
@@ -801,6 +803,34 @@ static int tegra_display_hub_probe(struct platform_device *pdev)
return err;
}
+ hub->num_heads = of_get_child_count(pdev->dev.of_node);
+
+ hub->clk_heads = devm_kcalloc(&pdev->dev, hub->num_heads, sizeof(clk),
+ GFP_KERNEL);
+ if (!hub->clk_heads)
+ return -ENOMEM;
+
+ for (i = 0; i < hub->num_heads; i++) {
+ child = of_get_next_child(pdev->dev.of_node, child);
+ if (!child) {
+ dev_err(&pdev->dev, "failed to find node for head %u\n",
+ i);
+ return -ENODEV;
+ }
+
+ clk = devm_get_clk_from_child(&pdev->dev, child, "dc");
+ if (IS_ERR(clk)) {
+ dev_err(&pdev->dev, "failed to get clock for head %u\n",
+ i);
+ of_node_put(child);
+ return PTR_ERR(clk);
+ }
+
+ hub->clk_heads[i] = clk;
+ }
+
+ of_node_put(child);
+
/* XXX: enable clock across reset? */
err = reset_control_assert(hub->rst);
if (err < 0)
@@ -840,12 +870,16 @@ static int tegra_display_hub_remove(struct platform_device *pdev)
static int __maybe_unused tegra_display_hub_suspend(struct device *dev)
{
struct tegra_display_hub *hub = dev_get_drvdata(dev);
+ unsigned int i = hub->num_heads;
int err;
err = reset_control_assert(hub->rst);
if (err < 0)
return err;
+ while (i--)
+ clk_disable_unprepare(hub->clk_heads[i]);
+
clk_disable_unprepare(hub->clk_hub);
clk_disable_unprepare(hub->clk_dsc);
clk_disable_unprepare(hub->clk_disp);
@@ -856,6 +890,7 @@ static int __maybe_unused tegra_display_hub_suspend(struct device *dev)
static int __maybe_unused tegra_display_hub_resume(struct device *dev)
{
struct tegra_display_hub *hub = dev_get_drvdata(dev);
+ unsigned int i;
int err;
err = clk_prepare_enable(hub->clk_disp);
@@ -870,13 +905,22 @@ static int __maybe_unused tegra_display_hub_resume(struct device *dev)
if (err < 0)
goto disable_dsc;
+ for (i = 0; i < hub->num_heads; i++) {
+ err = clk_prepare_enable(hub->clk_heads[i]);
+ if (err < 0)
+ goto disable_heads;
+ }
+
err = reset_control_deassert(hub->rst);
if (err < 0)
- goto disable_hub;
+ goto disable_heads;
return 0;
-disable_hub:
+disable_heads:
+ while (i--)
+ clk_disable_unprepare(hub->clk_heads[i]);
+
clk_disable_unprepare(hub->clk_hub);
disable_dsc:
clk_disable_unprepare(hub->clk_dsc);
diff --git a/drivers/gpu/drm/tegra/hub.h b/drivers/gpu/drm/tegra/hub.h
index 6696a85fc1f2..479087c0705a 100644
--- a/drivers/gpu/drm/tegra/hub.h
+++ b/drivers/gpu/drm/tegra/hub.h
@@ -49,6 +49,9 @@ struct tegra_display_hub {
struct clk *clk_hub;
struct reset_control *rst;
+ unsigned int num_heads;
+ struct clk **clk_heads;
+
const struct tegra_display_hub_soc *soc;
struct tegra_windowgroup *wgrps;
};
--
2.19.1
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