On 29.11.2018 19:24, Thierry Reding wrote:
> 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;
> + }
I'm not sure that it's really worth to check that child is NULL here, we already know the exact number of children nodes. It could be omitted safely.
> +
> + 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;
> };
>
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