linux-kernel - Re: [PATCH v3 06/11] PCI: qcom: introduce qcom_clear_and_set

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Date:   Thu, 7 May 2020 13:07:43 -0500
From:   Rob Herring <robh@...nel.org>
To:     Ansuel Smith <ansuelsmth@...il.com>
Cc:     Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Mark Rutland <mark.rutland@....com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andrew Murray <amurray@...goodpenguin.co.uk>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 06/11] PCI: qcom: introduce qcom_clear_and_set_dword

On Fri, May 01, 2020 at 12:06:13AM +0200, Ansuel Smith wrote:
> Use qcom_clear_and_set_dword instead of use the same code many times in
> the entire driver.
> 
> Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> ---
>  drivers/pci/controller/dwc/pcie-qcom.c | 108 ++++++++++---------------
>  1 file changed, 41 insertions(+), 67 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
> index 921030a64bab..a4fd5baada34 100644
> --- a/drivers/pci/controller/dwc/pcie-qcom.c
> +++ b/drivers/pci/controller/dwc/pcie-qcom.c
> @@ -184,6 +184,16 @@ struct qcom_pcie {
>  
>  #define to_qcom_pcie(x)		dev_get_drvdata((x)->dev)
>  
> +static void qcom_clear_and_set_dword(void __iomem *addr, u32 clear_mask,
> +				     u32 set_mask)
> +{
> +	u32 val = readl(addr);
> +
> +	val &= ~clear_mask;
> +	val |= set_mask;
> +	writel(val, addr);
> +}

If we wanted this kind of register accessor in the kernel, then we'd 
have common ones. We don't because it hides the possible need for 
locking on a RMW sequence.

Also, not a fix. Don't mix refactoring with fixes.

Rob