linux-kernel - Re: [PATCH] PCI: xilinx-nwl: Enable the clock through CCF

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Date:   Wed, 23 Jun 2021 14:20:40 +0200
From:   Krzysztof Wilczyński <kw@...ux.com>
To:     Michal Simek <michal.simek@...inx.com>
Cc:     linux-kernel@...r.kernel.org, monstr@...str.eu, git@...inx.com,
        Hyun Kwon <hyun.kwon@...inx.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Rob Herring <robh@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH] PCI: xilinx-nwl: Enable the clock through CCF

Hi Michal,

Thank you for sending the patch over!

> Simply enable clocks. There is no remove function that's why
> this should be enough for simple operation.

What clock is this?  Would it be worth mentioning what it is for
a reference (and for posterity) the commit message?

Also why it would need to be enabled and wasn't before?  Would this be
a fix for some problem?  Would this warrant a "Fixes:" tag?  And would
it need to be back-ported to stable kernels?

[...]
> @@ -823,6 +825,11 @@ static int nwl_pcie_probe(struct platform_device *pdev)
>  		return err;
>  	}
>  
> +	pcie->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(pcie->clk))
> +		return PTR_ERR(pcie->clk);
> +	clk_prepare_enable(pcie->clk);
> +
[...]

Almost every other user of clk_prepare_enable() would check for
potential failure, print an appropriate message, and then do the
necessary clean-up before bailing out and returning an error.

Would adding an error check for clk_prepare_enable() and printing an
error message using dev_err() be too much in this case?  If not, then
I would rather follow the pattern that other users established and
handle errors as needed.  What do you think?

	Krzysztof