linux-kernel - Re: [PATCH v7 06/10] PCI: imx6: Fix the missing reference clock disable logic

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Message-ID: <Z4lFrNNkwhl+PuXz@lizhi-Precision-Tower-5810>
Date: Thu, 16 Jan 2025 12:45:16 -0500
From: Frank Li <Frank.li@....com>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Richard Zhu <hongxing.zhu@....com>, l.stach@...gutronix.de,
	bhelgaas@...gle.com, lpieralisi@...nel.org, kw@...ux.com,
	manivannan.sadhasivam@...aro.org, robh@...nel.org,
	krzk+dt@...nel.org, conor+dt@...nel.org, shawnguo@...nel.org,
	s.hauer@...gutronix.de, festevam@...il.com, imx@...ts.linux.dev,
	kernel@...gutronix.de, linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 06/10] PCI: imx6: Fix the missing reference clock
 disable logic

On Thu, Jan 16, 2025 at 11:01:14AM -0600, Bjorn Helgaas wrote:
> On Tue, Nov 26, 2024 at 03:56:58PM +0800, Richard Zhu wrote:
> > Ensure the *_enable_ref_clk() function is symmetric by addressing missing
> > disable parts on some platforms.
> >
> > Fixes: d0a75c791f98 ("PCI: imx6: Factor out ref clock disable to match enable")
>
> The patch below looks fine to me, and I guess it's more than just
> making the code prettier; it also actually *fixes* something, right?
>
> It looks like a functional change because imx_pcie_clk_enable() will
> now enable the IMX7D refclk when it didn't before, and
> imx_pcie_clk_disable() will disable the IMX6SX and IMX8M* refclk when
> it didn't before?
>
> But I don't think the Fixes: tag is correct.  I looked at uses of
> these symbols:
>
>   IMX6SX_GPR12_PCIE_TEST_POWERDOWN
>     enabled by imx6_pcie_enable_ref_clk()
>     disabled by imx6_pcie_assert_core_reset()
>
>   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL
>     enabled by imx6_pcie_init_phy()
>     disabled by imx6_pcie_clk_disable()
>
>   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE
>     enabled by imx6_pcie_enable_ref_clk()
>
> As far as I can tell, these uses are identical before and after
> d0a75c791f98 ("PCI: imx6: Factor out ref clock disable to match
> enable").

You can drop fixes tags

Frank
>
> > Signed-off-by: Richard Zhu <hongxing.zhu@....com>
> > Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > Reviewed-by: Frank Li <Frank.Li@....com>
> > ---
> >  drivers/pci/controller/dwc/pci-imx6.c | 24 ++++++++++++------------
> >  1 file changed, 12 insertions(+), 12 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> > index 413db182ce9f..ab2c97a8c327 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -599,10 +599,9 @@ static int imx_pcie_attach_pd(struct device *dev)
> >
> >  static int imx6sx_pcie_enable_ref_clk(struct imx_pcie *imx_pcie, bool enable)
> >  {
> > -	if (enable)
> > -		regmap_clear_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > -				  IMX6SX_GPR12_PCIE_TEST_POWERDOWN);
> > -
> > +	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > +			   IMX6SX_GPR12_PCIE_TEST_POWERDOWN,
> > +			   enable ? 0 : IMX6SX_GPR12_PCIE_TEST_POWERDOWN);
> >  	return 0;
> >  }
> >
> > @@ -631,19 +630,20 @@ static int imx8mm_pcie_enable_ref_clk(struct imx_pcie *imx_pcie, bool enable)
> >  {
> >  	int offset = imx_pcie_grp_offset(imx_pcie);
> >
> > -	if (enable) {
> > -		regmap_clear_bits(imx_pcie->iomuxc_gpr, offset, IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE);
> > -		regmap_set_bits(imx_pcie->iomuxc_gpr, offset, IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN);
> > -	}
> > -
> > +	regmap_update_bits(imx_pcie->iomuxc_gpr, offset,
> > +			   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE,
> > +			   enable ? 0 : IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE);
> > +	regmap_update_bits(imx_pcie->iomuxc_gpr, offset,
> > +			   IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN,
> > +			   enable ? IMX8MQ_GPR_PCIE_CLK_REQ_OVERRIDE_EN : 0);
> >  	return 0;
> >  }
> >
> >  static int imx7d_pcie_enable_ref_clk(struct imx_pcie *imx_pcie, bool enable)
> >  {
> > -	if (!enable)
> > -		regmap_set_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > -				IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> > +	regmap_update_bits(imx_pcie->iomuxc_gpr, IOMUXC_GPR12,
> > +			   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
> > +			   enable ? 0 : IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
> >  	return 0;
> >  }
> >
> > --
> > 2.37.1
> >