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Date:	Wed, 2 Apr 2014 13:17:01 -0400
From:	Murali Karicheri <m-karicheri2@...com>
To:	Arnd Bergmann <arnd@...db.de>, <xobs@...agi.com>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Richard Zhu <r65037@...escale.com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Mohit Kumar <mohit.kumar@...com>,
	Jingoo Han <jg1.han@...sung.com>,
	"Shilimkar, Santosh" <santosh.shilimkar@...com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Shawn Guo <shawn.guo@...aro.org>
Subject: Re: [RESEND: RFC PATCH 3/3] pcie: keystone: add pcie driver based
 on designware core driver

Arnd,

Thanks for reviewing the RFC patch. Please see below my response.

On 3/25/2014 3:44 AM, Arnd Bergmann wrote:
> On Monday 24 March 2014 20:35:26 Murali Karicheri wrote:
>> +
>> +int k2_pcie_platform_setup(struct platform_device *pdev)
>> +{
>> +	struct resource *phy_base_r, *devstat_r;
>> +	void __iomem *phy_base, *devstat;
>> +	u32 val;
>> +	int i;
>> +
>> +	devstat_r = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> +						 "reg_devcfg");
>> +	if (!devstat_r)
>> +		return -ENODEV;
> It seems you have a distinct register set for the PHY that you are
> driving here. Why not make this part generic PHY API driver?

Will investigate

>> +static int ks_pcie_establish_link(struct keystone_pcie *ks_pcie)
>> +{
>> +	struct pcie_port *pp = &ks_pcie->pp;
>> +	int count = 0;
>> +
>> +	dw_pcie_setup_rc(pp);
>> +
>> +	/* check if the link is up or not */
>> +	while (!dw_pcie_link_up(pp)) {
>> +		mdelay(100);
>> +		count++;
>> +		if (count == 10)
>> +			return -EINVAL;
>> +	}
>> +	return 0;
>> +}
> You are blocking the CPU for up to one second here, which is really
> nasty. Please find a way to move the code into a context where you
> can sleep and use msleep() instead, or better use an interrupt if the
> hardware supports that and use wait_for_completion().
Ok. I think I could use usleep_range() API here
>> +
>> +static void ks_pcie_msi_irq_handler(unsigned int irq, struct irq_desc *desc)
>> +{
>> +	struct keystone_pcie *ks_pcie = irq_desc_get_handler_data(desc);
>> +	u32 offset = irq - ks_pcie->msi_host_irqs[0], pending, vector;
>> +	struct pcie_port *pp = &ks_pcie->pp;
>> +	struct irq_chip *chip = irq_desc_get_chip(desc);
>> +	int src, virq;
> Did I understand this right that the MSI implementation can be used
> by any dw-pcie hardware of the same version? If so, it would be good
> to move it into an extra file so it can be shared with the next host
> driver that uses this version.
Yes. Can be moved to a separate file, dw-msi-v3.65.c ??

>> +/**
>> + * ks_pcie_set_outbound_trans() - Set PHYADDR <-> BUSADDR
>> + * mapping for outbound
>> + */
>> +static void ks_pcie_set_outbound_trans(struct keystone_pcie *ks_pcie)
>> +static void ks_pcie_set_inbound_trans(struct pcie_port *pp)
> Why do you need to set this up from the kernel? Please move the
> translation window setup into the boot loader if you can.

Why to create a u-boot dependency?
>> +static struct hw_pci keystone_pcie_hw = {
>> +	.nr_controllers	= 1,
>> +	.setup		= dw_pcie_setup,
>> +	.scan		= ks_pcie_scan_bus,
>> +	.swizzle        = pci_common_swizzle,
>> +	.add_bus	= dw_pcie_add_bus,
>> +	.map_irq	= ks_pcie_map_irq,
>> +};
> This can just be a local variable in the probe function.

Ok

>
>> +
>> +static int ks_pcie_map_irq(const struct pci_dev *dev, u8 slot, u8 pin)
>> +{
>> +	struct pcie_port *pp = sys_to_pcie(dev->bus->sysdata);
>> +	struct keystone_pcie *ks_pcie = to_keystone_pcie(pp);
>> +
>> +	dev_info(pp->dev, "ks_pcie_map_irq: pin %d\n", pin);
>> +
>> +	if (!pin || pin > ks_pcie->num_legacy_host_irqs) {
>> +		dev_err(pp->dev, "pci irq pin out of range\n");
>> +		return -1;
>> +	}
>> +
>> +	/* pin has values from 1-4 */
>> +	return (ks_pcie->virqs[pin - 1] >= 0) ?
>> +		ks_pcie->virqs[pin - 1] : -1;
>> +}
>> +
>> +
>> +static void ack_irq(struct irq_data *d)
>> +{
>> +}
>> +
>> +static void mask_irq(struct irq_data *d)
>> +{
>> +}
>> +
>> +static void unmask_irq(struct irq_data *d)
>> +{
>> +}
>> +
>> +static struct irq_chip ks_pcie_legacy_irq_chip = {
>> +	.name = "PCIe-LEGACY-IRQ",
>> +	.irq_ack = ack_irq,
>> +	.irq_mask = mask_irq,
>> +	.irq_unmask = unmask_irq,
>> +};
> Can you use the generic irqchip code here?

Will investigate.

>
>> +	/*
>> +	 * support upto MAX_LEGACY_HOST_IRQS host and legacy IRQs.
>> +	 * In dt from index 0 to 3
>> +	 */
>> +	for (i = 0; i < MAX_LEGACY_HOST_IRQS; i++) {
>> +		ks_pcie->legacy_host_irqs[i] = irq_of_parse_and_map(np, i);
>> +		if (ks_pcie->legacy_host_irqs[i] < 0)
>> +			break;
>> +		ks_pcie->num_legacy_host_irqs++;
>> +	}
>> +
>> +	if (ks_pcie->num_legacy_host_irqs) {
>> +		ks_pcie->legacy_irqd = irq_domain_add_linear(np,
>> +					ks_pcie->num_legacy_host_irqs,
>> +					&irq_domain_simple_ops, NULL);
>> +
>> +		if (!ks_pcie->legacy_irqd) {
>> +			dev_err(dev,
>> +				"Failed to add irq domain for legacy irqs\n");
>> +			return -EINVAL;
>> +		}
>> +	}
>> +
>> +	for (i = 0; i < ks_pcie->num_legacy_host_irqs; i++) {
>> +		ks_pcie->virqs[i] =
>> +			irq_create_mapping(ks_pcie->legacy_irqd, i);
>> +		irq_set_chip_and_handler(ks_pcie->virqs[i],
>> +			&ks_pcie_legacy_irq_chip, handle_level_irq);
>> +		irq_set_chip_data(ks_pcie->virqs[i], ks_pcie);
>> +		set_irq_flags(ks_pcie->virqs[i], IRQF_VALID);
>> +
>> +		if (ks_pcie->legacy_host_irqs[i] >= 0) {
>> +			irq_set_handler_data(ks_pcie->legacy_host_irqs[i],
>> +				ks_pcie);
>> +			irq_set_chained_handler(ks_pcie->legacy_host_irqs[i],
>> +				ks_pcie_legacy_irq_handler);
>> +		}
>> +		set_irq_flags(ks_pcie->legacy_host_irqs[i], IRQF_VALID);
>> +	}
> 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.

Will investigate

>> +	ks_pcie->clk = devm_clk_get(&pdev->dev, "pcie");
>> +	if (IS_ERR(ks_pcie->clk)) {
>> +		dev_err(&pdev->dev, "Failed to get pcie rc clock\n");
>> +		return PTR_ERR(ks_pcie->clk);
>> +	}
>> +	ret = clk_prepare_enable(ks_pcie->clk);
>> +	if (ret)
>> +		return ret;
> Could you move the clock handling into the generic dw-pcie code?

Could be. But currently only pci-exynos.c is using a clock name 
"pcie".pci-imx6.c uses pcie_axi" and
will have to be fixed so that we can move this code to the generic 
dw-pcie code.  Sean Cross is the
author for pci-imx6.c.

Sean,

Is "pcie_axi" is the pcie hw clock? If so, can you rename this to "pcie" 
so that  my patch can move the
clock handling code to pcie designware code?

>
>> +
>> +/* Keystone PCIe driver does not allow module unload */
>> +static int __init ks_pcie_init(void)
>> +{
>> +	return platform_driver_probe(&ks_pcie_driver, ks_pcie_probe);
>> +}
>> +subsys_initcall(ks_pcie_init);
> Why subsys_initcall?
>
> We should probably try to fix unloading soon.

Replied in another thread already from Andrew.

>
>> diff --git a/drivers/pci/host/pcie-ks-pdata.h b/drivers/pci/host/pcie-ks-pdata.h
>> new file mode 100644
>> index 0000000..a7626de
>> --- /dev/null
>> +++ b/drivers/pci/host/pcie-ks-pdata.h
>> @@ -0,0 +1,19 @@
>> +/*
>> + * Copyright (C) 2013-2014 Texas Instruments., Ltd.
>> + *		http://www.ti.com
>> + *
>> + * Author: Murali Karicheri <m-karicheri2@...com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + */
>> +
>> +/* platform specific setup for k2 pcie */
>> +int k2_pcie_platform_setup(struct platform_device *pdev);
>> +
>> +/* keystone pcie pdata configurations */
>> +struct keystone_pcie_pdata {
>> +	int (*setup)(struct platform_device *pdev);
>> +};
> This should all go away once you have a proper PHY driver.
Will investigate.
>
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index 3a02717..7c3f777 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -3461,3 +3461,15 @@ int pci_dev_specific_acs_enabled(struct pci_dev *dev, u16 acs_flags)
>>   
>>   	return -ENOTTY;
>>   }
>> +
>> +#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.

Will investigate.

>
> 	Arnd
>

Murali

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