[1/2] dt-bindings: display: tegra: Add source clock for SOR

From: Thierry Reding <treding@nvidia.com>

The SOR clock can have various sources, with the most commonly used
being the sor_safe, pll_d2_out0, pll_dp and sor_brick clocks. These
are configured using a three level mux, of which the first 2 levels
can be treated as one. The direct parents of the SOR clock are the
sor_safe, sor_brick and sor_src clocks, whereas the pll_d2_out0 and
pll_dp clocks can be selected as parents of the sor_src clock via a
second mux.

Previous generations of Tegra have only supported eDP and LVDS with
the SOR, where LVDS was never used on publicly available hardware.
Clocking for this only ever required the first level mux (to select
between sor_safe and sor_brick).

Tegra210 has a new revision of the SOR that supports HDMI and hence
needs to support the second level mux to allow selecting pll_d2_out0
as the SOR clock's parent. This second mux is knows as sor_src, and
operating system software needs a reference to it in order to select
the proper parent.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
 .../devicetree/bindings/display/tegra/nvidia,tegra20-host1x.txt          | 1 +
 1 file changed, 1 insertion(+)

On Thu, Jun 23, 2016 at 12:27:59PM +0200, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
> 
> When running in HDMI mode, the sor1 IP block needs to use the sor1_src
> as parent clock, and in turn configure the sor1_src to use pll_d2_out0
> as its parent.
> 
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
>  drivers/gpu/drm/tegra/sor.c | 14 +++++++++++++-
>  1 file changed, 13 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tegra/sor.c b/drivers/gpu/drm/tegra/sor.c
> index 6887e52318e2..7405c39f6db3 100644
> --- a/drivers/gpu/drm/tegra/sor.c
> +++ b/drivers/gpu/drm/tegra/sor.c
> @@ -172,6 +172,7 @@ struct tegra_sor {
>  	struct clk *clk_parent;
>  	struct clk *clk_brick;
>  	struct clk *clk_safe;
> +	struct clk *clk_src;
>  	struct clk *clk_dp;
>  	struct clk *clk;
>  
> @@ -2140,7 +2141,11 @@ static void tegra_sor_hdmi_enable(struct drm_encoder *encoder)
>  	tegra_sor_writel(sor, 0x00000000, SOR_XBAR_POL);
>  
>  	/* switch to parent clock */
> -	err = tegra_sor_set_parent_clock(clk, sor->clk_parent);
> +	err = clk_set_parent(sor->clk_src, sor->clk_parent);
> +	if (err < 0)
> +		dev_err(sor->dev, "failed to set source clock: %d\n", err);
> +
> +	err = tegra_sor_set_parent_clock(sor, sor->clk_src);
>  	if (err < 0)
>  		dev_err(sor->dev, "failed to set parent clock: %d\n", err);
>  
> @@ -2645,6 +2650,13 @@ static int tegra_sor_probe(struct platform_device *pdev)
>  		goto remove;
>  	}
>  
> +	sor->clk_src = devm_clk_get(&pdev->dev, "source");
> +	if (IS_ERR(sor->clk_src)) {
> +		err = PTR_ERR(sor->clk_src);
> +		dev_err(&pdev->dev, "failed to get source clock: %d\n", err);
> +		goto remove;

Shouldn't this fallback to current behavior without this clock?

> +	}
> +
>  	sor->clk_parent = devm_clk_get(&pdev->dev, "parent");
>  	if (IS_ERR(sor->clk_parent)) {
>  		err = PTR_ERR(sor->clk_parent);
> -- 
> 2.8.3
> 
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