On Tue, Nov 13, 2012 at 12:38:34PM +0800, Mark Zhang wrote:
> On 11/12/2012 05:39 PM, Mark Zhang wrote:
> > On 11/09/2012 09:20 PM, Thierry Reding wrote:
[...]
> >> @@ -1036,9 +1041,6 @@ static struct clk_duplicate tegra_clk_duplicates[] = {
> >> CLK_DUPLICATE("usbd", "utmip-pad", NULL),
> >> CLK_DUPLICATE("usbd", "tegra-ehci.0", NULL),
> >> CLK_DUPLICATE("usbd", "tegra-otg", NULL),
> >> - CLK_DUPLICATE("hdmi", "tegradc.0", "hdmi"),
> >> - CLK_DUPLICATE("hdmi", "tegradc.1", "hdmi"),
> >> - CLK_DUPLICATE("host1x", "tegra_grhost", "host1x"),
> >> CLK_DUPLICATE("2d", "tegra_grhost", "gr2d"),
> >> CLK_DUPLICATE("3d", "tegra_grhost", "gr3d"),
> >> CLK_DUPLICATE("epp", "tegra_grhost", "epp"),
> >> @@ -1051,6 +1053,9 @@ static struct clk_duplicate tegra_clk_duplicates[] = {
> >> CLK_DUPLICATE("pll_p_out3", "tegra-i2c.1", "fast-clk"),
> >> CLK_DUPLICATE("pll_p_out3", "tegra-i2c.2", "fast-clk"),
> >> CLK_DUPLICATE("pll_p_out3", "tegra-i2c.3", "fast-clk"),
> >> + CLK_DUPLICATE("pll_p", "tegra-dc.0", "parent"),
> >> + CLK_DUPLICATE("pll_p", "tegra-dc.1", "parent"),
> >> + CLK_DUPLICATE("pll_d_out0", "tegra-hdmi", "parent"),
> >> };
>
> Why we need this "CLK_DUPLICATE"? Set the clock parent of the dc
> controllers to pll_p?
This was the method proposed by Stephen to abstract away the clock tree
differences between Tegra20 and Tegra30. The way this works is that we
can {devm_,}clk_get(&pdev->dev, "parent") in the display and HDMI
controllers' .probe() and it'll obtain the correct parent clock
independent of which version of Tegra is used.
Thierry
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