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Subject: Re: [PATCH 17/30] PCI: tegra: Use switch statements in
 tegra_pcie_isr()
To:     Thierry Reding <thierry.reding@gmail.com>
CC:     <bhelgaas@google.com>, <robh+dt@kernel.org>,
        <mark.rutland@arm.com>, <jonathanh@nvidia.com>,
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References: <20190411170355.6882-1-mmaddireddy@nvidia.com>
 <20190411170355.6882-18-mmaddireddy@nvidia.com> <20190415132523.GS29254@ulmo>
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From:   Manikanta Maddireddy <mmaddireddy@nvidia.com>
Message-ID: <a34fd1ff-67ad-5f1d-4ba2-12a5e48bf187@nvidia.com>
Date:   Mon, 15 Apr 2019 20:55:22 +0530
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On 15-Apr-19 6:55 PM, Thierry Reding wrote:
> On Thu, Apr 11, 2019 at 10:33:42PM +0530, Manikanta Maddireddy wrote:
>> Use switch statements in tegra_pcie_isr() for better code readability.
>>
>> Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
>> ---
>>  drivers/pci/controller/pci-tegra.c | 37 ++++++++++++++++--------------
>>  1 file changed, 20 insertions(+), 17 deletions(-)
>>
>> diff --git a/drivers/pci/controller/pci-tegra.c b/drivers/pci/controller/pci-tegra.c
>> index cdaaf13a9fd7..cf2715065a53 100644
>> --- a/drivers/pci/controller/pci-tegra.c
>> +++ b/drivers/pci/controller/pci-tegra.c
>> @@ -842,36 +842,39 @@ static irqreturn_t tegra_pcie_isr(int irq, void *arg)
>>  	};
>>  	struct tegra_pcie *pcie = arg;
>>  	struct device *dev = pcie->dev;
>> -	u32 code, signature;
>> +	u32 code, signature, fpci;
>> +	u64 address;
>>  
>>  	code = afi_readl(pcie, AFI_INTR_CODE) & AFI_INTR_CODE_MASK;
>>  	signature = afi_readl(pcie, AFI_INTR_SIGNATURE);
>>  	afi_writel(pcie, 0, AFI_INTR_CODE);
>>  
>> -	if (code == AFI_INTR_LEGACY)
>> -		return IRQ_NONE;
>> -
>>  	if (code >= ARRAY_SIZE(err_msg))
>> -		code = 0;
>> +		return IRQ_NONE;
>>  
>> +	switch (code) {
>> +	case AFI_INTR_LEGACY:
>> +		return IRQ_NONE;
>>  	/*
>>  	 * do not pollute kernel log with master abort reports since they
>>  	 * happen a lot during enumeration
>>  	 */
>> -	if (code == AFI_INTR_MASTER_ABORT)
>> +	case AFI_INTR_MASTER_ABORT:
>>  		dev_dbg(dev, "%s, signature: %08x\n", err_msg[code], signature);
>> -	else
>> +		fpci = afi_readl(pcie, AFI_UPPER_FPCI_ADDRESS) & 0xff;
>> +		address = (u64)fpci << 32 | (signature & 0xfffffffc);
>> +		dev_dbg(dev, "  FPCI address: %10llx\n", address);
>> +		break;
>> +	case AFI_INTR_TARGET_ABORT:
>> +	case AFI_INTR_FPCI_DECODE_ERROR:
>>  		dev_err(dev, "%s, signature: %08x\n", err_msg[code], signature);
>> -
>> -	if (code == AFI_INTR_TARGET_ABORT || code == AFI_INTR_MASTER_ABORT ||
>> -	    code == AFI_INTR_FPCI_DECODE_ERROR) {
>> -		u32 fpci = afi_readl(pcie, AFI_UPPER_FPCI_ADDRESS) & 0xff;
>> -		u64 address = (u64)fpci << 32 | (signature & 0xfffffffc);
>> -
>> -		if (code == AFI_INTR_MASTER_ABORT)
>> -			dev_dbg(dev, "  FPCI address: %10llx\n", address);
>> -		else
>> -			dev_err(dev, "  FPCI address: %10llx\n", address);
>> +		fpci = afi_readl(pcie, AFI_UPPER_FPCI_ADDRESS) & 0xff;
>> +		address = (u64)fpci << 32 | (signature & 0xfffffffc);
>> +		dev_err(dev, "  FPCI address: %10llx\n", address);
>> +		break;
>> +	default:
>> +		dev_err(dev, "%s, signature: %08x\n", err_msg[code], signature);
>> +		break;
>>  	}
>>  
>>  	return IRQ_HANDLED;
> I don't think this improves readability. It does duplicate some code and
> is actually longer than the previous variant, so I don't think this adds
> value.
>
> Thierry
There is multiple conditions check in single "if" statement and there is if-else statement
inside "if", so I felt switch case makes it more clear. I agree there is duplicate code.

Manikanta