RE: [PATCH v3 0/9] add the imx8m pcie phy driver and imx8mm pcie support

From: Richard Zhu
Date: Wed Oct 27 2021 - 21:51:52 EST

> -----Original Message-----
> From: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> Sent: Wednesday, October 27, 2021 11:41 PM
> To: Richard Zhu <hongxing.zhu@xxxxxxx>
> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>; Kishon Vijay Abraham I
> <kishon@xxxxxx>; vkoul@xxxxxxxxxx; Rob Herring <robh@xxxxxxxxxx>;
> galak@xxxxxxxxxxxxxxxxxxx; Shawn Guo <shawnguo@xxxxxxxxxx>;
> linux-phy@xxxxxxxxxxxxxxxxxxx; Device Tree Mailing List
> <devicetree@xxxxxxxxxxxxxxx>; Linux ARM Mailing List
> <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list
> <linux-kernel@xxxxxxxxxxxxxxx>; Sascha Hauer <kernel@xxxxxxxxxxxxxx>;
> dl-linux-imx <linux-imx@xxxxxxx>
> Subject: Re: [PATCH v3 0/9] add the imx8m pcie phy driver and imx8mm
> pcie support
>
> On Tue, Oct 26, 2021 at 11:18 PM Richard Zhu <hongxing.zhu@xxxxxxx>
> wrote:
> >
> > > -----Original Message-----
> > > From: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> > > Sent: Wednesday, October 27, 2021 12:06 AM
> > > To: Richard Zhu <hongxing.zhu@xxxxxxx>
> > > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>; Kishon Vijay Abraham I
> > > <kishon@xxxxxx>; vkoul@xxxxxxxxxx; Rob Herring <robh@xxxxxxxxxx>;
> > > galak@xxxxxxxxxxxxxxxxxxx; Shawn Guo <shawnguo@xxxxxxxxxx>;
> > > linux-phy@xxxxxxxxxxxxxxxxxxx; Device Tree Mailing List
> > > <devicetree@xxxxxxxxxxxxxxx>; Linux ARM Mailing List
> > > <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list
> > > <linux-kernel@xxxxxxxxxxxxxxx>; Sascha Hauer
> > > <kernel@xxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>
> > > Subject: Re: [PATCH v3 0/9] add the imx8m pcie phy driver and
> imx8mm
> > > pcie support
> > >
> > > On Mon, Oct 25, 2021 at 10:41 PM Richard Zhu
> <hongxing.zhu@xxxxxxx>
> > > wrote:
> > > >
> > > > > -----Original Message-----
> > > > > From: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> > > > > Sent: Tuesday, October 26, 2021 1:15 AM
> > > > > To: Richard Zhu <hongxing.zhu@xxxxxxx>
> > > > > Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>; Kishon Vijay Abraham I
> > > > > <kishon@xxxxxx>; vkoul@xxxxxxxxxx; Rob Herring
> > > > > <robh@xxxxxxxxxx>; galak@xxxxxxxxxxxxxxxxxxx; Shawn Guo
> > > > > <shawnguo@xxxxxxxxxx>; linux-phy@xxxxxxxxxxxxxxxxxxx; Device
> > > > > Tree Mailing List <devicetree@xxxxxxxxxxxxxxx>; Linux ARM
> > > > > Mailing List <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; open list
> > > > > <linux-kernel@xxxxxxxxxxxxxxx>; Sascha Hauer
> > > > > <kernel@xxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>
> > > > > Subject: Re: [PATCH v3 0/9] add the imx8m pcie phy driver and
> > > > > imx8mm pcie support
> > > > >
> > > > > On Mon, Oct 25, 2021 at 12:23 AM Richard Zhu
> > > > > <hongxing.zhu@xxxxxxx>
> > > > > wrote:
> > > > > >
> > > > > > Snipped...
> > > > > >
> > > > > > > > > > > > > My boards do not use CLKREQ# so I do not have
> > > > > > > > > > > > > that defined in pinmux and I found that if I add
> > > > > > > > > > > > > MX8MM_IOMUXC_I2C4_SCL_PCIE1_CLKREQ_B
> > > > > > > > > > > PCIe
> > > > > > > > > > > > > works on my board but this isn't a solution just
> > > > > > > > > > > > > a work-around (I have boards that use the only
> > > > > > > > > > > > > two possible pins for CLKREQ as other
> > > > > > > > > > > features).
> > > > > > > > > > > > >
> > > > > > > > > > > > > Similarly you will find on the imx8mm-evk if you
> > > > > > > > > > > > > comment out the CLKREQ (which isn't required)
> > > > > > > > > > > > > the imx8mmevk will end up hanging like my
> > > > > > > > > > > boards:
> > > > > > > > > > > > [Richard Zhu] Hi Tim:
> > > > > > > > > > > > Regarding the SPEC, the CLKREQ# is mandatory
> > > > > > > > > > > > required, and should be
> > > > > > > > > > > configured as an open drain, active low signal.
> > > > > > > > > > > > And this signal should be driven low by the PCIe
> > > > > > > > > > > > M.2 device to request the
> > > > > > > > > > > REF clock be available(active low).
> > > > > > > > > > > > So, there is such kind of CLKREQ# pin definition
> > > > > > > > > > > > on i.MX8MM EVK
> > > > > > > > board.
> > > > > > > > > > > >
> > > > > > > > > > > > Anyway, I think the external OSC circuit should be
> > > > > > > > > > > > always running if there is
> > > > > > > > > > > no CLKREQ# on your HW board design.
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > The way I understand it is CLKREQ# allows the host
> > > > > > > > > > > to disable the REFCLK when not needed for power
> > > > > > > > > > > savings so it would seem optional to implement that
> > > > > > > > > > > and if not implemented should be left unconnected on
> > > > > > > > the card.
> > > > > > > > > > >
> > > > > > > > > > [Richard Zhu] No, not that way. Regarding the SPEC,
> > > > > > > > > > this signal is
> > > > > > > > mandatory required.
> > > > > > > > > > Especially for the L1ss usages. This signal would be
> > > > > > > > > > OD(open drain), bi-directional, and might be driven
> > > > > > > > > > low/high by RC or EP automatically if
> > > > > > > > L1ss modes are enabled.
> > > > > > > > > > You can make reference to the
> > > > > > > > > >
> "ECN_L1_PM_Substates_with_CLKREQ_31_May_2013_Rev10a",
> > > or
> > > > > the
> > > > > > > > chapter 5.5 L1 PM Substates of "PCI Express Base
> Specification, Rev.
> > > > > > > > 4.0 Version 1.0".
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > CLKREQ is only mandatory if you wish to support clock
> > > > > > > > > power management. Many boards with a PCI host
> controller
> > > > > > > > > do not support this.
> > > > > > > [Richard Zhu] Okay, understood.
> > > > > > >
> > > > > > > > >
> > > > > > > > > > > > > diff --git
> > > > > > > > > > > > > a/arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi
> > > > > > > > > > > > > b/arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi
> > > > > > > > > > > > > index 5ce43daa0c8b..f0023b48f475 100644
> > > > > > > > > > > > > ---
> > > > > > > > > > > > > a/arch/arm64/boot/dts/freescale/imx8mm-evk.dtsi
> > > > > > > > > > > > > +++
> b/arch/arm64/boot/dts/freescale/imx8mm-evk.d
> > > > > > > > > > > > > +++ tsi
> > > > > > > > > > > > > @@ -448,7 +448,9 @@
> > > > > > > > > > > > >
> > > > > > > > > > > > > pinctrl_pcie0: pcie0grp {
> > > > > > > > > > > > > fsl,pins = <
> > > > > > > > > > > > > +/*
> > > > > > > > > > > > >
> > > > > > > > > > > > > MX8MM_IOMUXC_I2C4_SCL_PCIE1_CLKREQ_B
> 0x61
> > > > > > > > > > > > > +*/
> > > > > > > > > > > > >
> > > > > > > > > > > MX8MM_IOMUXC_SAI2_RXFS_GPIO4_IO21
> > > > > > > > > > > > > 0x41
> > > > > > > > > > > > > >;
> > > > > > > > > > > > > };
> > > > > > > > > > > > >
> > > > > > > > > > > > > I have PCIe working with a driver that I ported
> > > > > > > > > > > > > from NXP's kernel which differs from your driver
> > > > > > > > > > > > > in that the PCIe PHY is not abstracted to its
> > > > > > > > > > > > > own driver so I think this has something to do
> > > > > > > > > > > > > with the order in which the phy is reset or
> > > > > > > initialized?
> > > > > > > > > > > > > The configuration of
> > > > > > > > > > > gpr14 bits looks correct to me.
> > > > > > > > > > > > [Richard Zhu] The CLKREQ# PIN definition shouldn't
> > > > > > > > > > > > be
> > > masked.
> > > > > > > > > > > > In the NXP's local BSP kernel, I just force
> > > > > > > > > > > > CLKREQ# low to level up the HW
> > > > > > > > > > > compatibility.
> > > > > > > > > > > > That's might the reason why the PCIe works on your
> > > > > > > > > > > > HW board although the
> > > > > > > > > > > CLKREQ# PIN is not defined.
> > > > > > > > > > > > This method is a little rude and violate the SPEC,
> > > > > > > > > > > > and not recommended
> > > > > > > > > > > although it levels up the HW compatibility.
> > > > > > > > > > > > So I drop this method in this series.
> > > > > > > > > > > >
> > > > > > > > > > >
> > > > > > > > > > > Sorry, I don't understand what you are saying here.
> > > > > > > > > > > Is there a change you are going to make to v4 that
> > > > > > > > > > > will make this work for the evk and my boards? What
> > > > > > > > > > > is that change
> > > exactly?
> > > > > > > > > > [Richard Zhu] No. What I said above is that the
> > > > > > > > > > CLKREQ# is forced to be low in NXP local BSP kernel. I
> > > > > > > > > > guess this might be the reason why your
> > > > > > > > board works.
> > > > > > > > > >
> > > > > > > > > > BIT11 and BIT10 of IOMUXC_GPR14 can be used to force
> > > > > > > > > > the CLKREQ# to
> > > > > > > > be low.
> > > > > > > > > > Set CLKREQ_OVERRIDE_EN(bit10) 1b1, then write one
> zero
> > > > > > > > > > to
> > > > > > > > CLKREQ_OVERRIDE(bit11).
> > > > > > > > > >
> > > > > > > > >
> > > > > > > > > Ok, that makes sense. Those bits are not explained well
> > > > > > > > > in the IMX8MMRM. As my board's external REFCLK is
> always
> > > > > > > > > enabled that must gate the clock internally to the host
> > > > > > > > > controller
> > > block.
> > > > > > > > >
> > > > > > > > > I can confirm that asserting those GPR14 bits does
> > > > > > > > > resolve my
> > > issue:
> > > > > > > > >
> > > > > > > > > #define IMX8MM_GPR_PCIE_CLKREQ_OVERRIDE_VAL
> BIT(11)
> > > > > > > > > #define IMX8MM_GPR_PCIE_CLKREQ_OVERRIDE_EN
> > > BIT(10)
> > > > > > > > >
> > > > > > > > > /*
> > > > > > > > > * for boards that do not connect CLKREQ#,
> > > > > > > > > * override CLKREQ# and drive it low internally
> > > > > > > > > */
> > > > > > > > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> > > > > IOMUXC_GPR14,
> > > > > > > > >
> > > > > > > > IMX8MM_GPR_PCIE_CLKREQ_OVERRIDE_VAL, 0);
> > > > > > > > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> > > > > IOMUXC_GPR14,
> > > > > > > > >
> > > > > > > > IMX8MM_GPR_PCIE_CLKREQ_OVERRIDE_EN, 1);
> > > > > > > [Richard Zhu] regmap bits operations should manipulate
> > > > > > > according
> > > bits.
> > > > > > > The BIT(10) and BIT(11) should be touched actually.
> > > > > > >
> > > > > > > > >
> > > > > > > > > Should this be added as a 'fsl,clkreq-unsupported' flag
> > > > > > > > > that needs to be set true to implement the above code?
> > > > > > > > >
> > > > > > > >
> > > > > > > > Richard,
> > > > > > > >
> > > > > > > > Sorry - spoke too soon. My test was flawed as I still was
> > > > > > > > pinmuxing CLKREQ in my dt to work around the issue and
> > > > > > > > after removed the above did not resolve my issue. The
> > > > > > > > setting of OVERRIDE_EN was wrong above (should not be set
> > > > > > > > to '1' but
> > > > > > > > BIT(10)
> > > > > > > > instead) but this code already exists in
> > > > > > > > imx6_pcie_enable_ref_clk and is used for IMX8MM per your
> > > > > > > > patch
> > > so this is not the issue.
> > > > > > > >
> > > > > > > > What makes my board work is to clear GPR14 bit9 (like the
> > > > > > > > NXP kernel
> > > > > > > > does) so I don't think this bit does what we think it does
> > > > > > > > (select between internal and ext clk). I think setting it
> > > > > > > > enables clock gating via
> > > > > > > CLKREQ#.
> > > > > > > >
> > > > > > > > This also points out that perhaps the CLKREQ_OVERRIDE
> > > > > > > > logic should be moved to the new phy driver for IMX8MM.
> > > > > > > [Richard Zhu] It sounds reasonable to consider to force the
> > > > > > > CLKREQ# to be low.
> > > > > > > I will think about that and add this in later v5 patch-set
> > > > > > > if nobody has different concerns.
> > > > > > > Thanks.
> > > > > > [Richard Zhu] Hi Tim:
> > > > > > As you mentioned above, the CLKREQ# GPIO PIN is not used for
> > > > > > PCIe on
> > > > > your board, right?
> > > > > > " (I have boards that use the only two possible pins for
> > > > > > CLKREQ as other
> > > > > features)"
> > > > > >
> > > > > > Did the override configuration of the clkreq# will bring
> > > > > > unexpected results
> > > > > for other features on your board?
> > > > > >
> > > > >
> > > > > What I mean is that imx8mm-venice-gw7901.dts uses both I2C4
> and
> > > > > UART4 and because I2C4_SCL and UART4_RXD are the only two
> pads
> > > > > that could be pinmuxed for CLKREQ# I can't use the workaround of
> > > > > pin muxing
> > > it.
> > > > >
> > > > > Currently your driver only works on my imx8mm-venice-* boards if
> > > > > I add one of the following on boards that don't connect those
> > > > > pads (or if I clear
> > > > > IMX8MM_GPR_PCIE_REF_USE_PAD):
> > > > > MX8MM_IOMUXC_I2C4_SCL_PCIE1_CLKREQ_B
> > > > > MX8MM_IOMUXC_UART4_RXD_PCIE1_CLKREQ_B
> > > > >
> > > > > Note your 'PCI: imx: add the imx8mm pcie support' patch [1] does
> > > > > enable this code already in the imx6_pcie_enable_ref_clk
> > > > > function to override REF_CLK and drive it low:
> > > > >
> > > > > offset = imx6_pcie_grp_offset(imx6_pcie);
> > > > > /*
> > > > > * Set the over ride low and enabled
> > > > > * make sure that REF_CLK is turned on.
> > > > > */
> > > > > regmap_update_bits(imx6_pcie->iomuxc_gpr, offset,
> > > > > IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE,
> > > > > 0);
> > > > > regmap_update_bits(imx6_pcie->iomuxc_gpr, offset,
> > > > > IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN,
> > > > > IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN);
> > > > >
> > > > > So this is already being run and yet my boards still do not work
> > > > > unless I clr IMX8MM_GPR_PCIE_REF_USE_PAD like this which is
> what
> > > > > the NXP downstream driver does:
> > > > > regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> > > > > IMX8MM_GPR_PCIE_REF_USE_PAD, 0);
> > > > >
> > > > > This is why I'm not sure that bit does what you think it does...
> > > > > I feel like that bit enables 'Use CLKREQ# to enable CLK'.
> > > > >
> > > > > You tell me the descriptions for GPR14 are wrong in the reference
> manual.
> > > > > Please provide correct descriptions for us so we can sort this out.
> > > > >
> > > > [Richard Zhu] Hi Tim:
> > > > The BIT9 of GPR14 is used as
> "GPR_PCIE1_PHY_I_AUX_EN_OVERRIDE_EN"
> > > > and BIT19 is used as "GPR_PCIE1_PHY_FUNC_I_AUX_EN" on
> i.MX8MM.
> > > > I think the two bits descriptions are used to describe the BIT19
> > > > and BIT9
> > > together refer to my guess.
> > > > {GPR_PCIE1_PHY_I_AUX_EN_OVERRIDE_EN(BIT9),
> > > > GPR_PCIE1_PHY_FUNC_I_AUX_EN(BIT19) }
> > > > 2'b00: External Reference Clock I/O (for PLL) Disable
> > > > 2'b01: External Reference Clock I/O (for PLL) Enable
> > > > 2'b10: External Reference Clock I/O (for PLL) Disable
> > > > 2'b11: External Reference Clock I/O (for PLL) output is controlled
> > > > by CLKREQ#
> > > >
> > > > The option1&3 should be forbidden, since the external REF CLK I/O
> > > > should
> > > be enabled on your board and EVK board.
> > > > In the option2&4, the BIT19 should be set to be 1'b1.'
> > > >
> > > > So, regarding my understand, if the CLKREQ# is not pinmuxed in
> > > > your use
> > > case, the IMX8MM_GPR_PCIE_REF_USE_PAD (BIT9) should be 1'b0.
> > > >
> > >
> > > Richard,
> > >
> > > Ok, if this is the case then drivers/pci/controller/dwc/pci-imx6.c
> > > for IMX8MM should not touch GPR14 and '[v3,9/9] PCI: imx: add the
> imx8mm pcie support'
> > > should have this on top and squashed:
> > > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > > b/drivers/pci/controller/dwc/pci-imx6.c
> > > index 7c89bd1a6441..458d54c8e385 100644
> > > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > > @@ -452,8 +452,12 @@ static int imx6_pcie_enable_ref_clk(struct
> > > imx6_pcie *imx6_pcie)
> > > break;
> > > case IMX7D:
> > > break;
> > > - case IMX8MQ:
> > > case IMX8MM:
> > > + ret = clk_prepare_enable(imx6_pcie->pcie_aux);
> > > + if (ret)
> > > + dev_err(dev, "unable to enable
> pcie_aux
> > > clock\n");
> > > + break;
> > > + case IMX8MQ:
> > > ret = clk_prepare_enable(imx6_pcie->pcie_aux);
> > > if (ret) {
> > > dev_err(dev, "unable to enable
> pcie_aux
> > > clock\n");
> > >
> > [Richard Zhu] Sorry, I might don't understand what's meaning of the
> changes.
> > What're the differences between before and after the changes?
> >
>
> The above change to your patch 'only' calls clk_prepare_enable for
> IMX8MM and does not touch GPR14 bits as the IMX8MQ case does
> (because as you point out the GPR14 bits differ between IMX8MM and
> IMX8MQ).
[Richard Zhu] Got that, thanks a lot.

>
> > >
> > > And your '[v3,5/9] phy: freescale: pcie: initialize the imx8 pcie
> > > standalone phy driver' should have this on top and squashed:
> > > diff --git a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > > b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > > index 317cf61bff37..27ca0b9f1d92 100644
> > > --- a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > > +++ b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > > @@ -43,7 +43,7 @@
> > > #define IMX8MM_GPR_PCIE_CMN_RST BIT(18)
> > > #define IMX8MM_GPR_PCIE_POWER_OFF BIT(17)
> > > #define IMX8MM_GPR_PCIE_SSC_EN BIT(16)
> > > -#define IMX8MM_GPR_PCIE_REF_USE_PAD BIT(9)
> > > +#define IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE BIT(9)
> > >
> > > struct imx8_pcie_phy {
> > > u32 refclk_pad_mode;
> > > @@ -63,12 +63,12 @@ static int imx8_pcie_phy_init(struct phy *phy)
> > > reset_control_assert(imx8_phy->reset);
> > >
> > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > > - IMX8MM_GPR_PCIE_REF_USE_PAD,
> > > - imx8_phy->refclk_pad_mode == 1 ?
> > > - IMX8MM_GPR_PCIE_REF_USE_PAD :
> 0);
> > > +
> IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE,
> > > + 0);
> > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > > IMX8MM_GPR_PCIE_AUX_EN,
> > > - IMX8MM_GPR_PCIE_AUX_EN);
> > > + imx8_phy->refclk_pad_mode ==
> > > IMX8_PCIE_REFCLK_PAD_INPUT ?
> > > + IMX8MM_GPR_PCIE_AUX_EN : 0);
> > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > > IMX8MM_GPR_PCIE_POWER_OFF,
> 0);
> > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14, @@
> > > -76,7 +76,7 @@ static int imx8_pcie_phy_init(struct phy *phy)
> > >
> > > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > >
> IMX8MM_GPR_PCIE_REF_CLK_SEL,
> > > - imx8_phy->refclk_pad_mode == 1 ?
> > > + imx8_phy->refclk_pad_mode ==
> > > IMX8_PCIE_REFCLK_PAD_INPUT ?
> > >
> IMX8MM_GPR_PCIE_REF_CLK_EXT :
> > >
> IMX8MM_GPR_PCIE_REF_CLK_PLL);
> > > usleep_range(100, 200);
> > >
> > > I tested this and it works both on imx8mm-evk and imx8mm-venice-*
> > > which both have external clkgen.
> > >
> > > However, the above does not set
> IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE for
> > > the case where CLKREQ# is connected and thus should be used so I
> > > think we need to add a property for that to define if CLKREQ# is
> > > hooked up or not. I tested enabling
> IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE
> > > and as expected that worked on the imx8mm-evk which hooks up
> CLKREQ#
> > > but not imx8mm-venice which does not hook up CLKREQ#.
> > >
> > > What do you think about adding a property for this?
> > [Richard Zhu] First of all, thanks a lot for your help to figure out the
> details.
> > Agree with your proposal.
> > One optional property "fsl,clkreq-unsupported" would be added for the
> CLKREQ# not hooked case later.
> >
> > diff --git
> > a/Documentation/devicetree/bindings/phy/fsl,imx8-pcie-phy.yaml
> > b/Documentation/devicetree/bindings/phy/fsl,imx8-pcie-phy.yaml
> > index 097ba2a28fb4..2264452924cc 100644
> > --- a/Documentation/devicetree/bindings/phy/fsl,imx8-pcie-phy.yaml
> > +++ b/Documentation/devicetree/bindings/phy/fsl,imx8-pcie-phy.yaml
> > @@ -58,6 +58,11 @@ properties:
> > $ref: /schemas/types.yaml#/definitions/uint32
> > default: 0
> >
> > + fsl,clkreq-unsupported:
> > + type: boolean
> > + description: A boolean property whoes presence indicates the
> CLKREQ#
> > + signal isn't supported in the HW board design (optional
> required).
> > +
>
> A boolean property indicating the CLKREQ# signal is not supported in the
> board design (optional)
[Richard Zhu] Okay, would be updated later.

>
> >
> > diff --git a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > index 07eea39283ed..4b4402eaddcc 100644
> > --- a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > +++ b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> > @@ -43,7 +43,7 @@
> > #define IMX8MM_GPR_PCIE_CMN_RST BIT(18)
> > #define IMX8MM_GPR_PCIE_POWER_OFF BIT(17)
> > #define IMX8MM_GPR_PCIE_SSC_EN BIT(16)
> > -#define IMX8MM_GPR_PCIE_REF_USE_PAD BIT(9)
> > +#define IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE BIT(9)
> >
> > struct imx8_pcie_phy {
> > void __iomem *base;
> > @@ -54,6 +54,7 @@ struct imx8_pcie_phy {
> > u32 refclk_pad_mode;
> > u32 tx_deemph_gen1;
> > u32 tx_deemph_gen2;
> > + bool clkreq_unused;
> > };
> >
> > static int imx8_pcie_phy_init(struct phy *phy) @@ -65,13 +66,15 @@
> > static int imx8_pcie_phy_init(struct phy *phy)
> > reset_control_assert(imx8_phy->reset);
> >
> > pad_mode = imx8_phy->refclk_pad_mode;
> > + /* Set AUX_EN_OVERRIDE 1'b0, when the CLKREQ# isn't
> hooked */
> > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > - IMX8MM_GPR_PCIE_REF_USE_PAD,
> > - pad_mode ==
> IMX8MM_GPR_PCIE_REF_USE_PAD ?
> > - IMX8MM_GPR_PCIE_REF_USE_PAD :
> 0);
> > +
> IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE,
> > + imx8_phy->clkreq_unused ?
> > + 0 :
> IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE);
> > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > IMX8MM_GPR_PCIE_AUX_EN,
> > - IMX8MM_GPR_PCIE_AUX_EN);
> > + pad_mode ==
> IMX8_PCIE_REFCLK_PAD_INPUT ?
> > + IMX8MM_GPR_PCIE_AUX_EN : 0);
> > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14,
> > IMX8MM_GPR_PCIE_POWER_OFF,
> 0);
> > regmap_update_bits(imx8_phy->iomuxc_gpr,
> IOMUXC_GPR14, @@
> > -171,6 +174,11 @@ static int imx8_pcie_phy_probe(struct
> platform_device *pdev)
> >
> &imx8_phy->tx_deemph_gen2))
> > imx8_phy->tx_deemph_gen2 = 0;
> >
> > + if (of_property_read_bool(np, "fsl,clkreq-unsupported"))
> > + imx8_phy->clkreq_unused = true;
> > + else
> > + imx8_phy->clkreq_unused = false;
> > +
> > imx8_phy->clk = devm_clk_get(dev, "ref");
> > if (IS_ERR(imx8_phy->clk)) {
> > dev_err(dev, "failed to get imx pcie phy clock\n");
> >
>
> Yes this looks good and works both on venice (with
> 'fsl,clkreq-unsupported' added) and on imx8mm-evk.
>
> Thanks for working through this with me and please cc me on your v4
> submission.
[Richard Zhu] Welcome. I'm glad to have your help. Thanks a lot.
>
> Best regards,
>
> Tim