linux-kernel - Re: [PATCH v5 03/12] PCI: brcmstb: Use common error handling code in brcm_pcie

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Message-ID: <20240807025252.GE3412@thinkpad>
Date: Wed, 7 Aug 2024 08:22:52 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To: Jim Quinlan <james.quinlan@...adcom.com>
Cc: linux-pci@...r.kernel.org, Nicolas Saenz Julienne <nsaenz@...nel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
	Cyril Brulebois <kibi@...ian.org>,
	Stanimir Varbanov <svarbanov@...e.de>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	bcm-kernel-feedback-list@...adcom.com, jim2101024@...il.com,
	Florian Fainelli <florian.fainelli@...adcom.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Rob Herring <robh@...nel.org>,
	Philipp Zabel <p.zabel@...gutronix.de>,
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-rpi-kernel@...ts.infradead.org>,
	"moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" <linux-arm-kernel@...ts.infradead.org>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v5 03/12] PCI: brcmstb: Use common error handling code in
 brcm_pcie_probe()

On Wed, Jul 31, 2024 at 06:28:17PM -0400, Jim Quinlan wrote:
> o Move the clk_prepare_enable() below the resource allocations.
> o Move the clk_prepare_enable() out of __brcm_pcie_remove() but
>   add it to the end of brcm_pcie_remove().
> o Add a jump target (clk_disable_unprepare) so that a bit of exception
>   handling can be better reused at the end of this function implementation.
> o Use dev_err_probe() where it makes sense.
> 
> Signed-off-by: Jim Quinlan <james.quinlan@...adcom.com>
> ---
>  drivers/pci/controller/pcie-brcmstb.c | 34 ++++++++++++---------------
>  1 file changed, 15 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
> index c08683febdd4..7595e7009192 100644
> --- a/drivers/pci/controller/pcie-brcmstb.c
> +++ b/drivers/pci/controller/pcie-brcmstb.c
> @@ -1473,7 +1473,6 @@ static void __brcm_pcie_remove(struct brcm_pcie *pcie)
>  		dev_err(pcie->dev, "Could not stop phy\n");
>  	if (reset_control_rearm(pcie->rescal))
>  		dev_err(pcie->dev, "Could not rearm rescal reset\n");
> -	clk_disable_unprepare(pcie->clk);
>  }
>  
>  static void brcm_pcie_remove(struct platform_device *pdev)
> @@ -1484,6 +1483,7 @@ static void brcm_pcie_remove(struct platform_device *pdev)
>  	pci_stop_root_bus(bridge->bus);
>  	pci_remove_root_bus(bridge->bus);
>  	__brcm_pcie_remove(pcie);
> +	clk_disable_unprepare(pcie->clk);
>  }
>  
>  static const int pcie_offsets[] = {
> @@ -1613,31 +1613,26 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  
>  	pcie->ssc = of_property_read_bool(np, "brcm,enable-ssc");
>  
> -	ret = clk_prepare_enable(pcie->clk);
> -	if (ret) {
> -		dev_err(&pdev->dev, "could not enable clock\n");
> -		return ret;
> -	}
>  	pcie->rescal = devm_reset_control_get_optional_shared(&pdev->dev, "rescal");
> -	if (IS_ERR(pcie->rescal)) {
> -		clk_disable_unprepare(pcie->clk);
> +	if (IS_ERR(pcie->rescal))
>  		return PTR_ERR(pcie->rescal);
> -	}
> +
>  	pcie->perst_reset = devm_reset_control_get_optional_exclusive(&pdev->dev, "perst");
> -	if (IS_ERR(pcie->perst_reset)) {
> -		clk_disable_unprepare(pcie->clk);
> +	if (IS_ERR(pcie->perst_reset))
>  		return PTR_ERR(pcie->perst_reset);
> -	}
>  
> -	ret = reset_control_reset(pcie->rescal);
> +	ret = clk_prepare_enable(pcie->clk);
>  	if (ret)
> -		dev_err(&pdev->dev, "failed to deassert 'rescal'\n");
> +		return dev_err_probe(&pdev->dev, ret, "could not enable clock\n");
> +
> +	ret = reset_control_reset(pcie->rescal);
> +	if (dev_err_probe(&pdev->dev, ret, "failed to deassert 'rescal'\n"))
> +		goto clk_disable_unprepare;
>  
>  	ret = brcm_phy_start(pcie);
>  	if (ret) {
>  		reset_control_rearm(pcie->rescal);
> -		clk_disable_unprepare(pcie->clk);
> -		return ret;
> +		goto clk_disable_unprepare;
>  	}
>  
>  	ret = brcm_pcie_setup(pcie);
> @@ -1654,10 +1649,8 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  	msi_np = of_parse_phandle(pcie->np, "msi-parent", 0);
>  	if (pci_msi_enabled() && msi_np == pcie->np) {
>  		ret = brcm_pcie_enable_msi(pcie);
> -		if (ret) {
> -			dev_err(pcie->dev, "probe of internal MSI failed");
> +		if (dev_err_probe(pcie->dev, ret, "probe of internal MSI failed"))
>  			goto fail;
> -		}
>  	}
>  
>  	bridge->ops = pcie->type == BCM7425 ? &brcm7425_pcie_ops : &brcm_pcie_ops;
> @@ -1678,6 +1671,9 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>  
>  fail:
>  	__brcm_pcie_remove(pcie);
> +clk_disable_unprepare:
> +	clk_disable_unprepare(pcie->clk);
> +

TBH, this is not improving the code readability. __brcm_pcie_remove() used to
free all the resources and now you just moved clk_disable_unprepare() out of it
to save 2 lines in probe(). And you ended up calling clk_disable_unprepare()
separately in brcm_pcie_remove().

So please remove the label and call clk_disable_unprepare() in the error path
(just 2 instances) and continue to use __brcm_pcie_remove() to free all
resources (I would've preferred to have separate error labels instead of calling
__brcm_pcie_remove() though, but not this).

- Mani

-- 
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