linux-kernel - Re: [PATCH v5 05/11] PCI: cadence: Extract link setup sequence from cdns_pcie_host

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Message-ID: <56b2bbcb-7181-4640-93b3-0cf3e2029367@bootlin.com>
Date: Tue, 14 May 2024 15:15:34 +0200
From: Thomas Richard <thomas.richard@...tlin.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
Cc: Linus Walleij <linus.walleij@...aro.org>,
 Bartosz Golaszewski <brgl@...ev.pl>, Tony Lindgren <tony@...mide.com>,
 Aaro Koskinen <aaro.koskinen@....fi>,
 Janusz Krzysztofik <jmkrzyszt@...il.com>, Vignesh R <vigneshr@...com>,
 Andi Shyti <andi.shyti@...nel.org>, Peter Rosin <peda@...ntia.se>,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Siddharth Vadapalli <s-vadapalli@...com>, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-omap@...r.kernel.org,
 linux-i2c@...r.kernel.org, linux-pci@...r.kernel.org,
 linux-arm-kernel@...ts.infradead.org, gregory.clement@...tlin.com,
 theo.lebrun@...tlin.com, thomas.petazzoni@...tlin.com, u-kumar1@...com
Subject: Re: [PATCH v5 05/11] PCI: cadence: Extract link setup sequence from
 cdns_pcie_host_setup()

On 4/16/24 16:16, Dan Carpenter wrote:
> On Tue, Apr 16, 2024 at 03:29:54PM +0200, Thomas Richard wrote:
>> diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> index 5b14f7ee3c79..93d9922730af 100644
>> --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
>> +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
>> @@ -497,6 +497,30 @@ static int cdns_pcie_host_init(struct device *dev,
>>  	return cdns_pcie_host_init_address_translation(rc);
>>  }
>>  
>> +int cdns_pcie_host_link_setup(struct cdns_pcie_rc *rc)
>> +{
>> +	struct cdns_pcie *pcie = &rc->pcie;
>> +	struct device *dev = rc->pcie.dev;
>> +	int ret;
>> +
>> +	if (rc->quirk_detect_quiet_flag)
>> +		cdns_pcie_detect_quiet_min_delay_set(&rc->pcie);
>> +
>> +	cdns_pcie_host_enable_ptm_response(pcie);
>> +
>> +	ret = cdns_pcie_start_link(pcie);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to start link\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = cdns_pcie_host_start_link(rc);
>> +	if (ret)
>> +		dev_dbg(dev, "PCIe link never came up\n");
> 
> If we're going to ignore this error the message should be a dev_err()
> at least.

Hello Dan,

In fact it could not be really an error.
If you physically don't have a device on the PCIe bus,
cdns_pcie_host_start_link() will not return 0.

So if we use dev_err(), we will always have the error if there is no
device on the PCIe bus.

Regards,

Thomas

-- 
Thomas Richard, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com