From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawn.guo@freescale.com (Shawn Guo) Date: Tue, 5 Aug 2014 15:30:01 +0800 Subject: [PATCH V1 3/3] ARM: imx6q: Add the clock route from external OSC to ESAI clock In-Reply-To: References: Message-ID: <20140805073000.GI2167@dragon> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, Aug 04, 2014 at 07:11:15PM +0800, Shengjiu Wang wrote: > This patch mainly adds the clock route from external 24.576MHz OSC to internal > ESAI clock via analog clock2 PADs on the SoC and pll4 so that ESAI can get an > entirely synchronous clock source against CS42888. > > [ 1, We found if using pll4 to generate a 24.576MHz from inernal 24.0MHz OSC, > we would get noise during the audio playback via ESAI->CS42888 even though > this generated clock's rate is equal to the external one statistically. It > might be resulted from the tiny difference between two clock source, which > might be crucial to the sensitive CODEC we use -- CS42888. So we here apply > the old 3.0.35 way to feed ESAI the same clock source as CS42888. > > 2, Ideally, we should use bypass mode for pll4 since we only need to get > the raw rate (24.576MHz) while currently bypass mode in clk-pllv3.c isn't > entirely supported: The clock rate would be fixed to 24.0MHz if setting to > bypass, which would cause child clock get an incorrect rate and the driver > who uses the child clock fail to derive a needed clock rate, and it might > be dangerous to involve the clk-pllv3.c driver to this fix. Thus we here > apply 3.0.35 way provisionally. ] Instead of hacking it around, I consider it's time to properly implement PLL bypass mode. It's essentially just another multiplexer. Shawn > > Expected result: > > anaclk2 0 1 24576000 > lvds2_in 0 1 24576000 > pll4_sel 0 1 24576000 > pll4_audio 0 1 786432000 > pll4_post_div 0 1 786432000 > pll4_audio_div 0 1 786432000 > esai_sel 0 1 786432000 > esai_pred 0 1 98304000 > esai_podf 0 1 24576000 > esai 0 1 24576000 > > Signed-off-by: Nicolin Chen > Signed-off-by: Shengjiu Wang > --- > arch/arm/mach-imx/clk-imx6q.c | 5 +++++ > arch/arm/mach-imx/mach-imx6q.c | 28 ++++++++++++++++++++++++++++ > 2 files changed, 33 insertions(+) > > diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c > index 927a062..2d3634f 100644 > --- a/arch/arm/mach-imx/clk-imx6q.c > +++ b/arch/arm/mach-imx/clk-imx6q.c > @@ -413,6 +413,10 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node) > of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data); > > clk_register_clkdev(clk[IMX6QDL_CLK_ENET_REF], "enet_ref", NULL); > + clk_register_clkdev(clk[IMX6QDL_CLK_PLL4_AUDIO_DIV], "pll4_audio_div", NULL); > + clk_register_clkdev(clk[IMX6QDL_CLK_PLL4_SEL], "pll4_sel", NULL); > + clk_register_clkdev(clk[IMX6QDL_CLK_LVDS2_IN], "lvds2_in", NULL); > + clk_register_clkdev(clk[IMX6QDL_CLK_ESAI_EXTAL], "esai_extal", NULL); > > if ((imx_get_soc_revision() != IMX_CHIP_REVISION_1_0) || > cpu_is_imx6dl()) { > @@ -456,6 +460,7 @@ static void __init imx6q_clocks_init(struct device_node *ccm_node) > > /* Audio-related clocks configuration */ > clk_set_parent(clk[IMX6QDL_CLK_SPDIF_SEL], clk[IMX6QDL_CLK_PLL3_PFD3_454M]); > + clk_set_parent(clk[IMX6QDL_CLK_ESAI_SEL], clk[IMX6QDL_CLK_PLL4_AUDIO_DIV]); > > /* All existing boards with PCIe use LVDS1 */ > if (IS_ENABLED(CONFIG_PCI_IMX6)) > diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c > index d51c6e9..ea24a96 100644 > --- a/arch/arm/mach-imx/mach-imx6q.c > +++ b/arch/arm/mach-imx/mach-imx6q.c > @@ -362,6 +362,28 @@ put_node: > of_node_put(np); > } > > +#define ESAI_AUDIO_MCLK 24576000 > + > +static void __init imx6q_audio_lvds2_init(void) > +{ > + struct clk *pll4_sel, *lvds2_in, *pll4_audio_div, *esai_extal; > + > + pll4_audio_div = clk_get_sys(NULL, "pll4_audio_div"); > + pll4_sel = clk_get_sys(NULL, "pll4_sel"); > + lvds2_in = clk_get_sys(NULL, "lvds2_in"); > + esai_extal = clk_get_sys(NULL, "esai_extal"); > + if (IS_ERR(pll4_audio_div) || IS_ERR(pll4_sel) || > + IS_ERR(lvds2_in) || IS_ERR(esai_extal)) > + return; > + > + if (clk_get_rate(lvds2_in) != ESAI_AUDIO_MCLK) > + return; > + > + clk_set_parent(pll4_sel, lvds2_in); > + clk_set_rate(pll4_audio_div, 786432000); > + clk_set_rate(esai_extal, ESAI_AUDIO_MCLK); > +} > + > static struct platform_device imx6q_cpufreq_pdev = { > .name = "imx6q-cpufreq", > }; > @@ -379,6 +401,12 @@ static void __init imx6q_init_late(void) > imx6q_opp_init(); > platform_device_register(&imx6q_cpufreq_pdev); > } > + > + if (of_machine_is_compatible("fsl,imx6q-sabreauto") > + || of_machine_is_compatible("fsl,imx6dl-sabreauto")) { > + imx6q_audio_lvds2_init(); > + } > + > } > > static void __init imx6q_map_io(void) > -- > 1.7.9.5 >