Re: [PATCH V2] PCI: rcar: Add the initialization of PCIe link in resume_noirq

[Marek Vasut <marek.vasut@gmail.com>]

On 3/7/19 9:50 PM, Bjorn Helgaas wrote:
> On Sun, Feb 17, 2019 at 02:24:41PM +0100, marek.vasut@gmail.com wrote:
>> From: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>
>>
>> Reestablish the PCIe link very early in the resume process in case it
>> went down to prevent PCI accesses from hanging the bus. Such accesses
>> can happen early in the PCI resume process, in the resume_noirq, thus
>> the link must be reestablished in the resume_noirq callback of the
>> driver.
>>
>> Signed-off-by: Kazufumi Ikeda <kaz-ikeda@xc.jp.nec.com>
>> Signed-off-by: Gaku Inami <gaku.inami.xw@bp.renesas.com>
>> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
>> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
>> Cc: Phil Edworthy <phil.edworthy@renesas.com>
>> Cc: Simon Horman <horms+renesas@verge.net.au>
>> Cc: Wolfram Sang <wsa@the-dreams.de>
>> Cc: linux-renesas-soc@vger.kernel.org
>> ---
>> V2: - Use BIT() macro for (1 << n)
>>     - Since polling in rcar_pcie_wait_for_dl() uses udelay(), do not
>>       add extra changes to this function anymore
>>     - Make resume_noirq return early and clean up parenthesis therein
>> ---
>>  drivers/pci/controller/pcie-rcar.c | 20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>>
>> diff --git a/drivers/pci/controller/pcie-rcar.c b/drivers/pci/controller/pcie-rcar.c
>> index c8febb009454..b8f8fb3bc640 100644
>> --- a/drivers/pci/controller/pcie-rcar.c
>> +++ b/drivers/pci/controller/pcie-rcar.c
>> @@ -46,6 +46,7 @@
>>  
>>  /* Transfer control */
>>  #define PCIETCTLR		0x02000
>> +#define  DL_DOWN		BIT(3)
>>  #define  CFINIT			1
> 
> I saw discussion after the V1 patch about using BIT() and making
> similar constants also use BIT() for consistency.  That makes sense to
> me, and I think the best way would be:
> 
>   1) in *this* patch, use "#define DL_DOWN 8"
>   2) in a followup patch, convert them all to BIT()
> 
> That way each revision of pcie-rcar.c is self-consistent.

But the BIT() macros are already cleaned , see commit
0ee40820989b330e24926d82953ffb9e1c7a8425

    PCI: rcar: Clean up the macros

>>  #define PCIETSTR		0x02004
>>  #define  DATA_LINK_ACTIVE	1
>> @@ -1130,6 +1131,7 @@ static int rcar_pcie_probe(struct platform_device *pdev)
>>  	pcie = pci_host_bridge_priv(bridge);
>>  
>>  	pcie->dev = dev;
>> +	platform_set_drvdata(pdev, pcie);
>>  
>>  	err = pci_parse_request_of_pci_ranges(dev, &pcie->resources, NULL);
>>  	if (err)
>> @@ -1221,10 +1223,28 @@ static int rcar_pcie_probe(struct platform_device *pdev)
>>  	return err;
>>  }
>>  
>> +static int rcar_pcie_resume_noirq(struct device *dev)
>> +{
>> +	struct rcar_pcie *pcie = dev_get_drvdata(dev);
>> +
>> +	if (rcar_pci_read_reg(pcie, PMSR) &&
>> +	    !(rcar_pci_read_reg(pcie, PCIETCTLR) & DL_DOWN))
>> +		return 0;
>> +
>> +	/* Re-establish the PCIe link */
>> +	rcar_pci_write_reg(pcie, CFINIT, PCIETCTLR);
>> +	return rcar_pcie_wait_for_dl(pcie);
>> +}
>> +
>> +static const struct dev_pm_ops rcar_pcie_pm_ops = {
>> +	.resume_noirq = rcar_pcie_resume_noirq,
>> +};
> 
> I think there's the beginning of a convention to use #ifdef
> CONFIG_PM_SLEEP around the ops themselves [1].  Otherwise I think
> we'll get a warning about unused code when CONFIG_PM_SLEEP is unset.

Only if I used SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() , but I set the
resume_noirq directly.

>>  static struct platform_driver rcar_pcie_driver = {
>>  	.driver = {
>>  		.name = "rcar-pcie",
>>  		.of_match_table = rcar_pcie_of_match,
>> +		.pm = &rcar_pcie_pm_ops,
>>  		.suppress_bind_attrs = true,
>>  	},
>>  	.probe = rcar_pcie_probe,
>> -- 
>> 2.19.2
>>
> 
> [1] https://lore.kernel.org/linux-pci/20180531042020.GQ39853@bhelgaas-glaptop.roam.corp.google.com
> 


-- 
Best regards,
Marek Vasut