linux-kernel - Re: [PATCH v1] ARM: imx6plus: enable internal routing of clk_enet

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Date:   Tue, 23 Jun 2020 19:53:36 +0800
From:   Shawn Guo <shawnguo@...nel.org>
To:     Sven Van Asbroeck <thesven73@...il.com>,
        Fugang Duan <fugang.duan@....com>
Cc:     Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] ARM: imx6plus: enable internal routing of
 clk_enet_ref where possible

Hi Fugang,

Can you take a look at this patch?  Thanks!

Shawn

On Sat, Jun 13, 2020 at 04:17:03PM -0400, Sven Van Asbroeck wrote:
> On imx6, the ethernet reference clock (clk_enet_ref) can be generated
> by either the imx6, or an external source (e.g. an oscillator or the
> PHY). When generated by the imx6, the clock source (from ANATOP)
> must be routed to the input of clk_enet_ref via two pads on the SoC,
> typically via a dedicated track on the PCB.
> 
> On an imx6 plus however, there is a new setting which enables this
> clock to be routed internally on the SoC, from its ANATOP clock
> source, straight to clk_enet_ref, without having to go through
> the SoC pads.
> 
> Board designs where the clock is generated by the imx6 should not
> be affected by routing the clock internally. Therefore on a plus,
> we can enable internal routing by default.
> 
> To: Shawn Guo <shawnguo@...nel.org>
> Cc: Sascha Hauer <s.hauer@...gutronix.de>
> Cc: Pengutronix Kernel Team <kernel@...gutronix.de>
> Cc: Fabio Estevam <festevam@...il.com>
> Cc: NXP Linux Team <linux-imx@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Sven Van Asbroeck <TheSven73@...il.com>
> ---
>  arch/arm/mach-imx/mach-imx6q.c              | 18 ++++++++++++++++++
>  include/linux/mfd/syscon/imx6q-iomuxc-gpr.h |  1 +
>  2 files changed, 19 insertions(+)
> 
> Tree: next-20200613
> 
> diff --git a/arch/arm/mach-imx/mach-imx6q.c b/arch/arm/mach-imx/mach-imx6q.c
> index 85c084a716ab..4d22567bb650 100644
> --- a/arch/arm/mach-imx/mach-imx6q.c
> +++ b/arch/arm/mach-imx/mach-imx6q.c
> @@ -203,6 +203,24 @@ static void __init imx6q_1588_init(void)
>  	else
>  		pr_err("failed to find fsl,imx6q-iomuxc-gpr regmap\n");
>  
> +	/*
> +	 * On imx6 plus, enet_ref from ANATOP/CCM can be internally routed to
> +	 * be the PTP clock source, instead of having to be routed through
> +	 * pads.
> +	 * Board designs which route the ANATOP/CCM clock through pads are
> +	 * unaffected when routing happens internally. So on these designs,
> +	 * route internally by default.
> +	 */
> +	if (clksel == IMX6Q_GPR1_ENET_CLK_SEL_ANATOP && cpu_is_imx6q() &&
> +			imx_get_soc_revision() >= IMX_CHIP_REVISION_2_0) {
> +		if (!IS_ERR(gpr))
> +			regmap_update_bits(gpr, IOMUXC_GPR5,
> +					IMX6Q_GPR5_ENET_TXCLK_SEL,
> +					IMX6Q_GPR5_ENET_TXCLK_SEL);
> +		else
> +			pr_err("failed to find fsl,imx6q-iomuxc-gpr regmap\n");
> +		}
> +
>  	clk_put(enet_ref);
>  put_ptp_clk:
>  	clk_put(ptp_clk);
> diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> index d4b5e527a7a3..eb65d48da0df 100644
> --- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> +++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
> @@ -240,6 +240,7 @@
>  #define IMX6Q_GPR4_IPU_RD_CACHE_CTL		BIT(0)
>  
>  #define IMX6Q_GPR5_L2_CLK_STOP			BIT(8)
> +#define IMX6Q_GPR5_ENET_TXCLK_SEL		BIT(9)
>  #define IMX6Q_GPR5_SATA_SW_PD			BIT(10)
>  #define IMX6Q_GPR5_SATA_SW_RST			BIT(11)
>  
> -- 
> 2.17.1
>