linux-kernel - Re: [PATCH v12 13/13] PCI: imx6: Disable clocks in reverse order of enable

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Date:   Wed, 15 Jun 2022 18:27:44 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Richard Zhu <hongxing.zhu@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Fabio Estevam <festevam@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kernel@...gutronix.de,
        linux-imx@....com, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH v12 13/13] PCI: imx6: Disable clocks in reverse order of
 enable

On Wed, Jun 15, 2022 at 06:15:51PM -0500, Bjorn Helgaas wrote:
> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> imx6_pcie_clk_enable() enables clocks in the order:
> 
>   pcie_phy
>   pcie_bus
>   pcie
>   imx6_pcie_enable_ref_clk
> 
> Change imx6_pcie_clk_disable() to disable them in the reverse order.
> 
> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index bd736aff94a3..738b5a732cef 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -655,10 +655,10 @@ static int imx6_pcie_clk_enable(struct imx6_pcie *imx6_pcie)
>  
>  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);
>  	imx6_pcie_disable_ref_clk(imx6_pcie);
> +	clk_disable_unprepare(imx6_pcie->pcie);
> +	clk_disable_unprepare(imx6_pcie->pcie_bus);
> +	clk_disable_unprepare(imx6_pcie->pcie_phy);

Please comment on this.  I have no actual information that this is the
right thing, but normally we disable things in the reverse order that
we enabled them.

And the error path of imx6_pcie_deassert_core_reset() definitely
disables pcie, pcie_bus, pcie_phy in that order, so it seems
reasonable to do the same here.

>  }
>  
>  static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
> -- 
> 2.25.1
> 
> 
> _______________________________________________
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> linux-arm-kernel@...ts.infradead.org
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