linux-kernel - Re: [RESEND: RFC PATCH 3/3] pcie: keystone: add pcie driver based on designware core driver

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Message-ID: <5342D47F.4010506@ti.com>
Date:	Mon, 7 Apr 2014 12:38:23 -0400
From:	Murali Karicheri <m-karicheri2@...com>
To:	Jason Gunthorpe <jgunthorpe@...idianresearch.com>
CC:	Arnd Bergmann <arnd@...db.de>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Richard Zhu <r65037@...escale.com>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	Jingoo Han <jg1.han@...sung.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Shilimkar, Santosh" <santosh.shilimkar@...com>,
	Mohit Kumar <mohit.kumar@...com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [RESEND: RFC PATCH 3/3] pcie: keystone: add pcie driver based
 on designware core driver

On 3/25/2014 12:54 PM, Jason Gunthorpe wrote:
> On Tue, Mar 25, 2014 at 08:44:36AM +0100, Arnd Bergmann wrote:
>
>> I have no idea how this would work with the standard interrupt-map property,
>> since the legacy interrupt host is now the same device as the pci host.
>>
>> Maybe it's better to move the legacy irqchip handling entirely out of
>> the driver and use a separate device node for the registers so it can
>> come with its own #interrupt-cells, and then refer to this irqchip from
>> the interrupt-map.
> The other DW PCI-E drivers are being fixed to use interrupt-map, so I
> think this driver should be fixed before it goes in as well.
Jason,

Could you send me a patch reference or branch that I can review to 
better understand
changes required in my driver to use the bindings you have described below?

Murali
> Other PCI-E hosts have handled this particular problem with a
> construction like this:
>
>         pcie@...00000 {
>                 compatible = "ti,keystone2-pcie";
>                 device_type = "pci";
>                 #address-cells = <3>;
>                 #size-cells = <2>;
>                 #interrupt-cells = <1>;
> 	       reg = ..
>
>                 pcie_intc: interrupt-controller {
>                    interrupt-controller;
> 		  #address-cells = <0>;
>                    #interrupt-cells = <1>;
>                 }
>
>                 interrupts =  ... enough to decode INTx;
>
> 	       interrtup-map = <0 0 0 1 &pcie_intc 1>, // INT A
> 	                       <0 0 0 2 &pcie_intc 2>, // INT B
>                                 <0 0 0 3 &pcie_intc 3>, // INT C
>                                 <0 0 0 4 &pcie_intc 4>; // INT D
>         }
>
> When the legacy irq domain is created it should be bound to the
> pcie_intc node, not to pcie node.
>
> ks_pcie_map_irq should be removed.
The latest dw core driver still had map_irq() being provided by the driver.
So any patch reference will help me understand that you describe here.

Thanks

Murali
>
>>> +#ifdef CONFIG_PCIE_KEYSTONE
>>> +/*
>>> + * The KeyStone PCIe controller has maximum read request size of 256 bytes.
>>> + * Force this configuration for all EP including bridges.
>>> + */
>>> +static void quirk_limit_readrequest(struct pci_dev *dev)
>>> +{
>>> +	pcie_set_readrq(dev, 256);
>>> +}
>>> +DECLARE_PCI_FIXUP_FINAL(PCI_ANY_ID, PCI_ANY_ID, quirk_limit_readrequest);
>>> +#endif /* CONFIG_TI_KEYSTONE_PCIE */
>> You can't do this:
>>
>> A quirk for a specific hardware must not be enabled by compile-time options.
>> You have to find a different way to do this.
> This configuration should happen automatically by the PCI core if the
> config spaces are correct. See pcie_write_mrrs, pcie_write_mps,
> pcie_bus_configure_settings, etc.
>
> Your host will need to conform to the PCI spec and provide a root
> port bridge header for this to work.
>
> Also, even in the keystone case the MRRS should not be globally forced
> like this, there may be other bridges in the system with a 128 byte
> MPS.
>
> Jason

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