linux-kernel - Re: [PATCH 1/2] ARM: tegra: Add Tegra20 host1x support

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Message-ID: <20121113080456.GB15983@avionic-0098.mockup.avionic-design.de>
Date:	Tue, 13 Nov 2012 09:04:56 +0100
From:	Thierry Reding <thierry.reding@...onic-design.de>
To:	Mark Zhang <markz@...dia.com>
Cc:	Stephen Warren <swarren@...dotorg.org>,
	"linux-tegra@...r.kernel.org" <linux-tegra@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] ARM: tegra: Add Tegra20 host1x support

On Tue, Nov 13, 2012 at 04:00:47PM +0800, Mark Zhang wrote:
> On 11/13/2012 03:52 PM, Thierry Reding wrote:
> > * PGP Signed by an unknown key
> > 
> > On Tue, Nov 13, 2012 at 03:45:00PM +0800, Mark Zhang wrote:
> >> On 11/09/2012 09:20 PM, Thierry Reding wrote:
> >>> @@ -116,6 +122,9 @@ static __initdata struct tegra_clk_init_table tegra_dt_clk_init_table[] = {
> >>>         { "sbc2",       "pll_p",        100000000,      false },
> >>>         { "sbc3",       "pll_p",        100000000,      false },
> >>>         { "sbc4",       "pll_p",        100000000,      false },
> >>> +       { "host1x",     "pll_c",        144000000,      false },
> >>> +       { "disp1",      "pll_p",        600000000,      false },
> >>> +       { "disp2",      "pll_p",        600000000,      false },
> >>
> >> I think here the parent of disp2 should be "pll_d_out0", not "pll_p".
> >> Right now pll_p has not a proper clock setting to make 148.5MHz 1080p
> >> HDMI happy. In addition, you add the 297MHz in pll_d frequency table
> >> next and I think this is for disp2 has a proper clock rate to support HDMI.
> > [...]
> >>> @@ -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"),
> >>>  };
> >>
> >> The same with my above comments, the tegra-dc.1's parent should be
> >> pll_d_out0.
> > 
> > The way this works is that for HDMI it is required that the DC and HDMI
> > blocks have the same parent. So what really happens is that once you
> > setup one of the DCs to work with HDMI, its clock will automatically be
> > reparented to the HDMI parent clock, which in this case is "pll_d_out0".
> > 
> 
> Are you sure about this? Is this a hardware feature? I know the dc and
> hdmi controller should have the same clock parent but I think this
> should be ensured by device driver...

It's implemented in tegra_output_hdmi_setup_clock().

Thierry

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