RE: [RESEND v2 4/5] PCI: imx6: Fix the clock reference handling unbalance when link never came up

-----Original Message-----
From: Bjorn Helgaas <helgaas@kernel.org>
Sent: Wednesday, October 27, 2021 12:39 AM
To: Richard Zhu <hongxing.zhu@nxp.com>
Cc: l.stach@pengutronix.de; bhelgaas@google.com;
lorenzo.pieralisi@arm.com; linux-pci@vger.kernel.org; dl-linux-imx
[off-list ref]; linux-arm-kernel@lists.infradead.org;
linux-kernel@vger.kernel.org; kernel@pengutronix.de
Subject: Re: [RESEND v2 4/5] PCI: imx6: Fix the clock reference handling
unbalance when link never came up

On Fri, Oct 22, 2021 at 08:02:17AM +0000, Richard Zhu wrote:

quoted

<snipped ...>

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-static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie) -{
-	clk_disable_unprepare(imx6_pcie->pcie);
-	clk_disable_unprepare(imx6_pcie->pcie_phy);
-	clk_disable_unprepare(imx6_pcie->pcie_bus);
-
-	switch (imx6_pcie->drvdata->variant) {
-	case IMX6SX:
-		clk_disable_unprepare(imx6_pcie->pcie_inbound_axi);
-		break;
-	case IMX7D:
-		regmap_update_bits(imx6_pcie->iomuxc_gpr,

IOMUXC_GPR12,

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-				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
-				   IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
-		break;
-	case IMX8MQ:
-		clk_disable_unprepare(imx6_pcie->pcie_aux);
-		break;
-	default:
-		break;

While you're at it, this "default: break;" thing is pointless.
Normally it's better to just *move* something without changing it
at all, but this is such a simple thing I think you could drop
this at the same time as the move.

[Richard Zhu] Okay, got that. Would remove the "default:break" later.

Thanks.

quoted

[Richard Zhu] I figure out that the default:break is required by
IMX6Q/IMX6QP.  So I just don't drop them in v3 patch-set.

That makes no sense.  The code is:

  +static void imx6_pcie_clk_disable(struct imx6_pcie *imx6_pcie)
  +{
  +       clk_disable_unprepare(imx6_pcie->pcie);
  +       clk_disable_unprepare(imx6_pcie->pcie_phy);
  +       clk_disable_unprepare(imx6_pcie->pcie_bus);
  +
  +       switch (imx6_pcie->drvdata->variant) {
  +       case IMX6SX:
  +               clk_disable_unprepare(imx6_pcie->pcie_inbound_axi);
  +               break;
  +       case IMX7D:
  +               regmap_update_bits(imx6_pcie->iomuxc_gpr,
IOMUXC_GPR12,
  +
IMX7D_GPR12_PCIE_PHY_REFCLK_SEL,
  +
IMX7D_GPR12_PCIE_PHY_REFCLK_SEL);
  +               break;
  +       case IMX8MQ:
  +               clk_disable_unprepare(imx6_pcie->pcie_aux);
  +               break;
  +       default:
  +               break;
  +       }
  +}

Why do you think it makes a difference to remove the
"default: break;"?  There is no executable code after it.
I don't see how IMX6Q/IMX6QP could depend on the default case.

BTW, I feel like a broken record, but your v3 posting still has inconsistent
subject line capitalization:

  PCI: imx6: move the clock disable function to a proper place
  PCI: dwc: add a new callback host exit function into host ops

It would be nice if they were consistent and contained more specific
information, e.g.,

  PCI: imx6: Move imx6_pcie_clk_disable() earlier
  PCI: dwc: Add dw_pcie_host_ops.host_exit() callback

[Richard Zhu] Got that, would change to be consistent and more specific information. Thanks a lot.

BR
Richard

Bjorn