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

From: Bjorn Helgaas
Date: Tue Oct 26 2021 - 12:38:48 EST


On Fri, Oct 22, 2021 at 08:02:17AM +0000, Richard Zhu wrote:
> <snipped ...>
> > >
> > > > > -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;
> > >
> > > 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.
> [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

Bjorn