linux-kernel - Re: [PATCH v2] soc: imx: imx8mp-blk-ctrl: Add PCIe SYSPLL configurations

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Message-ID: <aacc40f4d8f727a8e1be97c094d1e391a8f72012.camel@toradex.com>
Date:   Fri, 18 Nov 2022 10:47:52 +0000
From:   Marcel Ziswiler <marcel.ziswiler@...adex.com>
To:     "alexander.stein@...tq-group.com" <alexander.stein@...tq-group.com>,
        "lorenzo.pieralisi@....com" <lorenzo.pieralisi@....com>,
        "l.stach@...gutronix.de" <l.stach@...gutronix.de>,
        "hongxing.zhu@....com" <hongxing.zhu@....com>,
        "marex@...x.de" <marex@...x.de>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "tharvey@...eworks.com" <tharvey@...eworks.com>,
        "bhelgaas@...gle.com" <bhelgaas@...gle.com>,
        "richard.leitner@...ux.dev" <richard.leitner@...ux.dev>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-imx@....com" <linux-imx@....com>
Subject: Re: [PATCH v2] soc: imx: imx8mp-blk-ctrl: Add PCIe SYSPLL
 configurations

Hi Richard

On Fri, 2022-11-18 at 10:56 +0800, Richard Zhu wrote:
> Add PCIe SYSPLL configurations, thus the internal SYSPLL can be used as
> i.MX8MP PCIe reference clock.
> 
> The following properties of PHY dts node should be changed accordingly.
>   - Set 'fsl,refclk-pad-mode' as '<IMX8_PCIE_REFCLK_PAD_OUTPUT>'.
>   - Change 'clocks' to '<&clk IMX8MP_CLK_HSIO_AXI>'.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@....com>

Tested-by: Marcel Ziswiler <marcel.ziswiler@...adex.com>

This works perfectly fine on Verdin iMX8M Plus as well. I will update my previous PCIe-enablement commit
(device tree part) in that respect and (re-)submit it.

Thanks!

Cheers

Marcel

> ---
> v1->v2:
> Refer to Lucas' comments, don't expose IMX8MP_CLK_HSIO_ROOT to dts node.
> https://patchwork.ozlabs.org/project/linux-pci/patch/1666590189-1364-1-git-send-email-hongxing.zhu@nxp.com/
> 
> Use <&clk IMX8MP_CLK_HSIO_AXI> as referrence clock source when internal
> clock mode is used by i.MX8MP PCIe module.
> 
> Verified on i.MX8MP EVK board with removing R131/R132/R137/R138, and
> populating R135/R136.
> ---
>  drivers/soc/imx/imx8mp-blk-ctrl.c | 22 ++++++++++++++++++++++
>  1 file changed, 22 insertions(+)
> 
> diff --git a/drivers/soc/imx/imx8mp-blk-ctrl.c b/drivers/soc/imx/imx8mp-blk-ctrl.c
> index 0e3b6ba22f94..5ad20a8ea25e 100644
> --- a/drivers/soc/imx/imx8mp-blk-ctrl.c
> +++ b/drivers/soc/imx/imx8mp-blk-ctrl.c
> @@ -21,6 +21,16 @@
>  #define  USB_CLOCK_MODULE_EN   BIT(1)
>  #define  PCIE_PHY_APB_RST      BIT(4)
>  #define  PCIE_PHY_INIT_RST     BIT(5)
> +#define GPR_REG2               0x8
> +#define  P_PLL_MASK            GENMASK(5, 0)
> +#define  M_PLL_MASK            GENMASK(15, 6)
> +#define  S_PLL_MASK            GENMASK(18, 16)
> +#define  P_PLL                 (0xc << 0)
> +#define  M_PLL                 (0x320 << 6)
> +#define  S_PLL                 (0x4 << 16)
> +#define GPR_REG3               0xc
> +#define  PLL_CKE               BIT(17)
> +#define  PLL_RST               BIT(31)
>  
>  struct imx8mp_blk_ctrl_domain;
>  
> @@ -86,6 +96,18 @@ static void imx8mp_hsio_blk_ctrl_power_on(struct imx8mp_blk_ctrl *bc,
>         case IMX8MP_HSIOBLK_PD_PCIE_PHY:
>                 regmap_set_bits(bc->regmap, GPR_REG0,
>                                 PCIE_PHY_APB_RST | PCIE_PHY_INIT_RST);
> +
> +               /* Set the PLL configurations, P = 12, M = 800, S = 4. */
> +               regmap_update_bits(bc->regmap, GPR_REG2,
> +                                  P_PLL_MASK | M_PLL_MASK | S_PLL_MASK,
> +                                  P_PLL | M_PLL | S_PLL);
> +               udelay(1);
> +
> +               regmap_update_bits(bc->regmap, GPR_REG3, PLL_RST, PLL_RST);
> +               udelay(10);
> +
> +               /* Set 1b'1 to pll_cke of GPR_REG3 */
> +               regmap_update_bits(bc->regmap, GPR_REG3, PLL_CKE, PLL_CKE);
>                 break;
>         default:
>                 break;