Re: [PATCH v3 2/2] dwc: PCI: intel: Intel PCIe RC controller driver

[Dilip Kota <eswara.kota@linux.intel.com>]

[Got delivery failure mail; so re-sending the mail]

Hi Andrew Murray,

Please find my response inline.

On 9/9/2019 4:31 PM, Andrew Murray wrote:
> On Mon, Sep 09, 2019 at 02:51:03PM +0800, Dilip Kota wrote:
>> On 9/6/2019 7:20 PM, Andrew Murray wrote:
>>> On Fri, Sep 06, 2019 at 06:58:11PM +0800, Dilip Kota wrote:
>>>> Hi Andrew Murray,
>>>>
>>>> Thanks for the review. Please find my response inline.
>>>>
>>>> On 9/5/2019 6:45 PM, Andrew Murray wrote:
>>>>> On Wed, Sep 04, 2019 at 06:10:31PM +0800, Dilip Kota wrote:
>>>>>> Add support to PCIe RC controller on Intel Universal
>>>>>> Gateway SoC. PCIe controller is based of Synopsys
>>>>>> Designware pci core.
>>>>>>
>>>>>> Signed-off-by: Dilip Kota <eswara.kota@linux.intel.com>
>>>>>> ---
>>>>> Hi Dilip,
>>>>>
>>>>> Thanks for the patch, initial feedback below:
>>>>>
>>>>>> changes on v3:
>>>>>> 	Rename PCIe app logic registers with PCIE_APP prefix.
>>>>>> 	PCIE_IOP_CTRL configuration is not required. Remove respective code.
>>>>>> 	Remove wrapper functions for clk enable/disable APIs.
>>>>>> 	Use platform_get_resource_byname() instead of
>>>>>> 	  devm_platform_ioremap_resource() to be similar with DWC framework.
>>>>>> 	Rename phy name to "pciephy".
>>>>>> 	Modify debug message in msi_init() callback to be more specific.
>>>>>> 	Remove map_irq() callback.
>>>>>> 	Enable the INTx interrupts at the time of PCIe initialization.
>>>>>> 	Reduce memory fragmentation by using variable "struct dw_pcie pci"
>>>>>> 	  instead of allocating memory.
>>>>>> 	Reduce the delay to 100us during enpoint initialization
>>>>>> 	  intel_pcie_ep_rst_init().
>>>>>> 	Call  dw_pcie_host_deinit() during remove() instead of directly
>>>>>> 	  calling PCIe core APIs.
>>>>>> 	Rename "intel,rst-interval" to "reset-assert-ms".
>>>>>> 	Remove unused APP logic Interrupt bit macro definitions.
>>>>>>     	Use dwc framework's dw_pcie_setup_rc() for PCIe host specific
>>>>>> 	 configuration instead of redefining the same functionality in
>>>>>> 	 the driver.
>>>>>> 	Move the whole DT parsing specific code to intel_pcie_get_resources()
>>>>>>
>>>>>>     drivers/pci/controller/dwc/Kconfig          |  13 +
>>>>>>     drivers/pci/controller/dwc/Makefile         |   1 +
>>>>>>     drivers/pci/controller/dwc/pcie-intel-axi.c | 840 ++++++++++++++++++++++++++++
>>>>>>     3 files changed, 854 insertions(+)
>>>>>>     create mode 100644 drivers/pci/controller/dwc/pcie-intel-axi.c
>>>>>>
>>>>>> diff --git a/drivers/pci/controller/dwc/Kconfig b/drivers/pci/controller/dwc/Kconfig
>>>>>> index 6ea778ae4877..e44b9b6a6390 100644
>>>>>> --- a/drivers/pci/controller/dwc/Kconfig
>>>>>> +++ b/drivers/pci/controller/dwc/Kconfig
>>>>>> @@ -82,6 +82,19 @@ config PCIE_DW_PLAT_EP
>>>>>>     	  order to enable device-specific features PCI_DW_PLAT_EP must be
>>>>>>     	  selected.
>>>>>> +config PCIE_INTEL_AXI
>>>>>> +        bool "Intel AHB/AXI PCIe host controller support"
>>>>>> +        depends on PCI_MSI
>>>>>> +        depends on PCI
>>>>> I don't think the PCI dependency is required here.
>>>>>
>>>>> I'm also not sure why PCI_MSI is required, we select PCIE_DW_HOST which
>>>>> depends on PCI_MSI_IRQ_DOMAIN which depends on PCI_MSI.
>>>> Agree, dependency on PCI and PCI_MSI can be removed. I will remove it in
>>>> next patch revision.
>>>>>> +        depends on OF
>>>>>> +        select PCIE_DW_HOST
>>>>>> +        help
>>>>>> +          Say 'Y' here to enable support for Intel AHB/AXI PCIe Host
>>>>>> +	  controller driver.
>>>>>> +	  The Intel PCIe controller is based on the Synopsys Designware
>>>>>> +	  pcie core and therefore uses the Designware core functions to
>>>>>> +	  implement the driver.
>>>>> I can see this description is similar to others in the same Kconfig,
>>>>> however I'm not sure what value a user gains by knowing implementation
>>>>> details - it's helpful to know that PCIE_INTEL_AXI is based on the
>>>>> Designware core, but is it helpful to know that the Designware core
>>>>> functions are used?
>>>>>
>>>>>> +
>>>>>>     config PCI_EXYNOS
>>>>>>     	bool "Samsung Exynos PCIe controller"
>>>>>>     	depends on SOC_EXYNOS5440 || COMPILE_TEST
>>>>>> diff --git a/drivers/pci/controller/dwc/Makefile b/drivers/pci/controller/dwc/Makefile
>>>>>> index b085dfd4fab7..46e656ebdf90 100644
>>>>>> --- a/drivers/pci/controller/dwc/Makefile
>>>>>> +++ b/drivers/pci/controller/dwc/Makefile
>>>>>> @@ -3,6 +3,7 @@ obj-$(CONFIG_PCIE_DW) += pcie-designware.o
>>>>>>     obj-$(CONFIG_PCIE_DW_HOST) += pcie-designware-host.o
>>>>>>     obj-$(CONFIG_PCIE_DW_EP) += pcie-designware-ep.o
>>>>>>     obj-$(CONFIG_PCIE_DW_PLAT) += pcie-designware-plat.o
>>>>>> +obj-$(CONFIG_PCIE_INTEL_AXI) += pcie-intel-axi.o
>>>>>>     obj-$(CONFIG_PCI_DRA7XX) += pci-dra7xx.o
>>>>>>     obj-$(CONFIG_PCI_EXYNOS) += pci-exynos.o
>>>>>>     obj-$(CONFIG_PCI_IMX6) += pci-imx6.o
>>>>>> diff --git a/drivers/pci/controller/dwc/pcie-intel-axi.c b/drivers/pci/controller/dwc/pcie-intel-axi.c
>>>>>> new file mode 100644
>>>>>> index 000000000000..75607ce03ebf
>>>>>> --- /dev/null
>>>>>> +++ b/drivers/pci/controller/dwc/pcie-intel-axi.c
>>>>>> @@ -0,0 +1,840 @@
>>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>>> +/*
>>>>>> + * PCIe host controller driver for Intel AXI PCIe Bridge
>>>>>> + *
>>>>>> + * Copyright (c) 2019 Intel Corporation.
>>>>>> + */
>>>>>> +
>>>>>> +#include <linux/bitfield.h>
>>>>>> +#include <linux/clk.h>
>>>>>> +#include <linux/gpio/consumer.h>
>>>>>> +#include <linux/interrupt.h>
>>>>>> +#include <linux/iopoll.h>
>>>>>> +#include <linux/of_irq.h>
>>>>>> +#include <linux/of_pci.h>
>>>>>> +#include <linux/of_platform.h>
>>>>>> +#include <linux/phy/phy.h>
>>>>>> +#include <linux/platform_device.h>
>>>>>> +#include <linux/reset.h>
>>>>>> +
>>>>>> +#include "../../pci.h"
>>>>> Please remove this - it isn't needed.
>>>> Ok, will remove it in next patch revision.
>>>>>> +#include "pcie-designware.h"
>>>>>> +
>>>>>> +#define PCIE_CCRID				0x8
>>>>>> +
>>>>>> +#define PCIE_LCAP				0x7C
>>>>>> +#define PCIE_LCAP_MAX_LINK_SPEED		GENMASK(3, 0)
>>>>>> +#define PCIE_LCAP_MAX_LENGTH_WIDTH		GENMASK(9, 4)
>>>>> These look like the standard PCI Link Capabilities Register,
>>>>> can you use the standard ones defined in pci_regs.h? (see
>>>>> PCI_EXP_LNKCAP_SLS_*).
>>>>>
>>>>>> +
>>>>>> +/* Link Control and Status Register */
>>>>>> +#define PCIE_LCTLSTS				0x80
>>>>>> +#define PCIE_LCTLSTS_ASPM_ENABLE		GENMASK(1, 0)
>>>>>> +#define PCIE_LCTLSTS_RCB128			BIT(3)
>>>>>> +#define PCIE_LCTLSTS_LINK_DISABLE		BIT(4)
>>>>>> +#define PCIE_LCTLSTS_COM_CLK_CFG		BIT(6)
>>>>>> +#define PCIE_LCTLSTS_HW_AW_DIS			BIT(9)
>>>>>> +#define PCIE_LCTLSTS_LINK_SPEED			GENMASK(19, 16)
>>>>>> +#define PCIE_LCTLSTS_NEGOTIATED_LINK_WIDTH	GENMASK(25, 20)
>>>>>> +#define PCIE_LCTLSTS_SLOT_CLK_CFG		BIT(28)
>>>>> These look like the standard Link Control and Link Status register, can
>>>>> you use the standard ones defined in pci_regs.h? (see PCI_EXP_LNKCTL_*
>>>>> and PCI_EXP_LNKSTA_*).
>>>>>
>>>>>> +
>>>>>> +#define PCIE_LCTLSTS2				0xA0
>>>>>> +#define PCIE_LCTLSTS2_TGT_LINK_SPEED		GENMASK(3, 0)
>>>>>> +#define PCIE_LCTLSTS2_TGT_LINK_SPEED_25GT	0x1
>>>>>> +#define PCIE_LCTLSTS2_TGT_LINK_SPEED_5GT	0x2
>>>>>> +#define PCIE_LCTLSTS2_TGT_LINK_SPEED_8GT	0x3
>>>>>> +#define PCIE_LCTLSTS2_TGT_LINK_SPEED_16GT	0x4
>>>>> And these look like the standard Link Control Register 2 (see
>>>>> PCI_EXP_LNKCTL2_*).
>>>>>
>>>>> Most of the #defines above and below look just like standard PCI defines
>>>>> (for example those found in pci_regs.h) - both in terms of their name and
>>>>> what they do. Ideally where the functionality is the same or very similar,
>>>>> then we should use the standard PCI defines in (pci_regs.h). This helps
>>>>> readability/understanding, helps to identify duplicate code and reduces
>>>>> the size of your patch.
>>>>>
>>>>> Also the capability offsets (e.g. PCIE_LCTLSTS2) are also standard. The
>>>>> offsets you define are offset by an additional 0x70. E.g.i
>>>>> PCIE_LCTLSTS2 = 0xA0, and PCI_EXP_LNKCTL2 = 0x30. Perhaps abstracting
>>>>> this offset will allow you to use the standard pci defines?
>>>>>
>>>>> I haven't looked in much detail at the remainder of the defines, but
>>>>> the same rationale should apply.
>>>> Agree, that's a good point. I will define the offset macro and use the
>>>> macros defined in pci_regs.h.
>>>>>> +#define PCIE_LCTLSTS2_HW_AUTO_DIS		BIT(5)
>>>>>> +
>>>>>> +/* Ack Frequency Register */
>>>>>> +#define PCIE_AFR				0x70C
>>>>>> +#define PCIE_AFR_FTS_NUM			GENMASK(15, 8)
>>>>>> +#define PCIE_AFR_COM_FTS_NUM			GENMASK(23, 16)
>>>>>> +#define PCIE_AFR_GEN12_FTS_NUM_DFT		(SZ_128 - 1)
>>>>>> +#define PCIE_AFR_GEN3_FTS_NUM_DFT		180
>>>>>> +#define PCIE_AFR_GEN4_FTS_NUM_DFT		196
>>>>>> +
>>>>>> +#define PCIE_PLCR_DLL_LINK_EN			BIT(5)
>>>>>> +#define PCIE_PORT_LOGIC_FTS			GENMASK(7, 0)
>>>>>> +#define PCIE_PORT_LOGIC_DFT_FTS_NUM		(SZ_128 - 1)
>>>>>> +
>>>>>> +#define PCIE_MISC_CTRL				0x8BC
>>>>>> +#define PCIE_MISC_CTRL_DBI_RO_WR_EN		BIT(0)
>>>>>> +
>>>>>> +#define PCIE_MULTI_LANE_CTRL			0x8C0
>>>>>> +#define PCIE_UPCONFIG_SUPPORT			BIT(7)
>>>>>> +#define PCIE_DIRECT_LINK_WIDTH_CHANGE		BIT(6)
>>>>>> +#define PCIE_TARGET_LINK_WIDTH			GENMASK(5, 0)
>>>>>> +
>>>>>> +/* APP RC Core Control Register */
>>>>>> +#define PCIE_APP_CCR				0x10
>>>>>> +#define PCIE_APP_CCR_LTSSM_ENABLE		BIT(0)
>>>>>> +
>>>>>> +/* PCIe Message Control */
>>>>>> +#define PCIE_APP_MSG_CR				0x30
>>>>>> +#define PCIE_APP_MSG_XMT_PM_TURNOFF		BIT(0)
>>>>>> +
>>>>>> +/* PCIe Power Management Control */
>>>>>> +#define PCIE_APP_PMC				0x44
>>>>>> +#define PCIE_APP_PMC_IN_L2			BIT(20)
>>>>>> +
>>>>>> +/* Interrupt Enable Register */
>>>>>> +#define PCIE_APP_IRNEN				0xF4
>>>>>> +#define PCIE_APP_IRNCR				0xF8
>>>>>> +#define PCIE_APP_IRN_AER_REPORT			BIT(0)
>>>>>> +#define PCIE_APP_IRN_PME			BIT(2)
>>>>>> +#define PCIE_APP_IRN_RX_VDM_MSG			BIT(4)
>>>>>> +#define PCIE_APP_IRN_PM_TO_ACK			BIT(9)
>>>>>> +#define PCIE_APP_IRN_LINK_AUTO_BW_STAT		BIT(11)
>>>>>> +#define PCIE_APP_IRN_BW_MGT			BIT(12)
>>>>>> +#define PCIE_APP_IRN_MSG_LTR			BIT(18)
>>>>>> +#define PCIE_APP_IRN_SYS_ERR_RC			BIT(29)
>>>>>> +
>>>>>> +#define PCIE_APP_INTX_OFST	12
>>>>>> +#define PCIE_APP_IRN_INT	(PCIE_APP_IRN_AER_REPORT | PCIE_APP_IRN_PME | \
>>>>>> +			PCIE_APP_IRN_RX_VDM_MSG | PCIE_APP_IRN_SYS_ERR_RC | \
>>>>>> +			PCIE_APP_IRN_PM_TO_ACK | PCIE_APP_IRN_MSG_LTR | \
>>>>>> +			PCIE_APP_IRN_BW_MGT | PCIE_APP_IRN_LINK_AUTO_BW_STAT | \
>>>>>> +			(PCIE_APP_INTX_OFST + PCI_INTERRUPT_INTA) | \
>>>>>> +			(PCIE_APP_INTX_OFST + PCI_INTERRUPT_INTB) | \
>>>>>> +			(PCIE_APP_INTX_OFST + PCI_INTERRUPT_INTC) | \
>>>>>> +			(PCIE_APP_INTX_OFST + PCI_INTERRUPT_INTD))
>>>>>> +
>>>>>> +#define BUS_IATU_OFFS		SZ_256M
>>>>>> +#define RST_INTRVL_DFT_MS	100
>>>>>> +enum {
>>>>>> +	PCIE_LINK_SPEED_AUTO = 0,
>>>>>> +	PCIE_LINK_SPEED_GEN1,
>>>>>> +	PCIE_LINK_SPEED_GEN2,
>>>>>> +	PCIE_LINK_SPEED_GEN3,
>>>>>> +	PCIE_LINK_SPEED_GEN4,
>>>>>> +};
>>>>>> +
>>>>>> +struct intel_pcie_soc {
>>>>>> +	unsigned int pcie_ver;
>>>>>> +	unsigned int pcie_atu_offset;
>>>>>> +	u32 num_viewport;
>>>>>> +};
>>>>>> +
>>>>>> +struct intel_pcie_port {
>>>>>> +	struct dw_pcie		pci;
>>>>>> +	unsigned int		id; /* Physical RC Index */
>>>>>> +	void __iomem		*app_base;
>>>>>> +	struct gpio_desc	*reset_gpio;
>>>>>> +	u32			rst_interval;
>>>>>> +	u32			max_speed;
>>>>>> +	u32			link_gen;
>>>>>> +	u32			max_width;
>>>>>> +	u32			lanes;
>>>>>> +	struct clk		*core_clk;
>>>>>> +	struct reset_control	*core_rst;
>>>>>> +	struct phy		*phy;
>>>>>> +};
>>>>>> +
>>>>>> +static void pcie_update_bits(void __iomem *base, u32 mask, u32 val, u32 ofs)
>>>>>> +{
>>>>>> +	u32 orig, tmp;
>>>>>> +
>>>>>> +	orig = readl(base + ofs);
>>>>>> +
>>>>>> +	tmp = (orig & ~mask) | (val & mask);
>>>>>> +
>>>>>> +	if (tmp != orig)
>>>>>> +		writel(tmp, base + ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static inline u32 pcie_app_rd(struct intel_pcie_port *lpp, u32 ofs)
>>>>>> +{
>>>>>> +	return readl(lpp->app_base + ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static inline void pcie_app_wr(struct intel_pcie_port *lpp, u32 val, u32 ofs)
>>>>>> +{
>>>>>> +	writel(val, lpp->app_base + ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static void pcie_app_wr_mask(struct intel_pcie_port *lpp,
>>>>>> +			     u32 mask, u32 val, u32 ofs)
>>>>>> +{
>>>>>> +	pcie_update_bits(lpp->app_base, mask, val, ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static inline u32 pcie_rc_cfg_rd(struct intel_pcie_port *lpp, u32 ofs)
>>>>>> +{
>>>>>> +	return dw_pcie_readl_dbi(&lpp->pci, ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static inline void pcie_rc_cfg_wr(struct intel_pcie_port *lpp, u32 val, u32 ofs)
>>>>>> +{
>>>>>> +	dw_pcie_writel_dbi(&lpp->pci, ofs, val);
>>>>>> +}
>>>>>> +
>>>>>> +static void pcie_rc_cfg_wr_mask(struct intel_pcie_port *lpp,
>>>>>> +				u32 mask, u32 val, u32 ofs)
>>>>>> +{
>>>>>> +	pcie_update_bits(lpp->pci.dbi_base, mask, val, ofs);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_mem_iatu(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	struct pcie_port *pp = &lpp->pci.pp;
>>>>>> +	phys_addr_t cpu_addr = pp->mem_base;
>>>>>> +
>>>>>> +	dw_pcie_prog_outbound_atu(&lpp->pci, PCIE_ATU_REGION_INDEX0,
>>>>>> +				  PCIE_ATU_TYPE_MEM, cpu_addr,
>>>>>> +				  pp->mem_base, pp->mem_size);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_ltssm_enable(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_app_wr_mask(lpp, PCIE_APP_CCR_LTSSM_ENABLE,
>>>>>> +			 PCIE_APP_CCR_LTSSM_ENABLE, PCIE_APP_CCR);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_ltssm_disable(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_app_wr_mask(lpp, PCIE_APP_CCR_LTSSM_ENABLE, 0, PCIE_APP_CCR);
>>>>>> +}
>>>>>> +
>>>>>> +static const char *pcie_link_gen_to_str(int gen)
>>>>>> +{
>>>>>> +	switch (gen) {
>>>>>> +	case PCIE_LINK_SPEED_GEN1:
>>>>>> +		return "2.5";
>>>>>> +	case PCIE_LINK_SPEED_GEN2:
>>>>>> +		return "5.0";
>>>>>> +	case PCIE_LINK_SPEED_GEN3:
>>>>>> +		return "8.0";
>>>>>> +	case PCIE_LINK_SPEED_GEN4:
>>>>>> +		return "16.0";
>>>>>> +	default:
>>>>>> +		return "???";
>>>>>> +	}
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_link_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 val;
>>>>>> +
>>>>>> +	val = pcie_rc_cfg_rd(lpp, PCIE_LCAP);
>>>>>> +	lpp->max_speed = FIELD_GET(PCIE_LCAP_MAX_LINK_SPEED, val);
>>>>>> +	lpp->max_width = FIELD_GET(PCIE_LCAP_MAX_LENGTH_WIDTH, val);
>>>>>> +
>>>>>> +	val = pcie_rc_cfg_rd(lpp, PCIE_LCTLSTS);
>>>>>> +
>>>>>> +	val &= ~(PCIE_LCTLSTS_LINK_DISABLE | PCIE_LCTLSTS_ASPM_ENABLE);
>>>>>> +	val |= (PCIE_LCTLSTS_SLOT_CLK_CFG | PCIE_LCTLSTS_COM_CLK_CFG |
>>>>>> +		PCIE_LCTLSTS_RCB128);
>>>>>> +	pcie_rc_cfg_wr(lpp, val, PCIE_LCTLSTS);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_max_speed_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 reg, val;
>>>>>> +
>>>>>> +	reg = pcie_rc_cfg_rd(lpp, PCIE_LCTLSTS2);
>>>>>> +	switch (lpp->link_gen) {
>>>>>> +	case PCIE_LINK_SPEED_GEN1:
>>>>>> +		reg &= ~PCIE_LCTLSTS2_TGT_LINK_SPEED;
>>>>>> +		reg |= PCIE_LCTLSTS2_HW_AUTO_DIS |
>>>>>> +			PCIE_LCTLSTS2_TGT_LINK_SPEED_25GT;
>>>>>> +		break;
>>>>>> +	case PCIE_LINK_SPEED_GEN2:
>>>>>> +		reg &= ~PCIE_LCTLSTS2_TGT_LINK_SPEED;
>>>>>> +		reg |= PCIE_LCTLSTS2_HW_AUTO_DIS |
>>>>>> +			PCIE_LCTLSTS2_TGT_LINK_SPEED_5GT;
>>>>>> +		break;
>>>>>> +	case PCIE_LINK_SPEED_GEN3:
>>>>>> +		reg &= ~PCIE_LCTLSTS2_TGT_LINK_SPEED;
>>>>>> +		reg |= PCIE_LCTLSTS2_HW_AUTO_DIS |
>>>>>> +			PCIE_LCTLSTS2_TGT_LINK_SPEED_8GT;
>>>>>> +		break;
>>>>>> +	case PCIE_LINK_SPEED_GEN4:
>>>>>> +		reg &= ~PCIE_LCTLSTS2_TGT_LINK_SPEED;
>>>>>> +		reg |= PCIE_LCTLSTS2_HW_AUTO_DIS |
>>>>>> +			PCIE_LCTLSTS2_TGT_LINK_SPEED_16GT;
>>>>>> +		break;
>>>>>> +	default:
>>>>>> +		/* Use hardware capability */
>>>>>> +		val = pcie_rc_cfg_rd(lpp, PCIE_LCAP);
>>>>>> +		val = FIELD_GET(PCIE_LCAP_MAX_LINK_SPEED, val);
>>>>>> +		reg &= ~PCIE_LCTLSTS2_HW_AUTO_DIS;
>>>>>> +		reg |= val;
>>>>>> +		break;
>>>>>> +	}
>>>>>> +	pcie_rc_cfg_wr(lpp, reg, PCIE_LCTLSTS2);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_speed_change_enable(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 mask, val;
>>>>>> +
>>>>>> +	mask = PORT_LOGIC_SPEED_CHANGE | PCIE_PORT_LOGIC_FTS;
>>>>>> +	val = PORT_LOGIC_SPEED_CHANGE | PCIE_PORT_LOGIC_DFT_FTS_NUM;
>>>>>> +
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, mask, val, PCIE_LINK_WIDTH_SPEED_CONTROL);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_speed_change_disable(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PORT_LOGIC_SPEED_CHANGE, 0,
>>>>>> +			    PCIE_LINK_WIDTH_SPEED_CONTROL);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_max_link_width_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 mask, val;
>>>>>> +
>>>>>> +	/* HW auto bandwidth negotiation must be enabled */
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PCIE_LCTLSTS_HW_AW_DIS, 0, PCIE_LCTLSTS);
>>>>>> +
>>>>>> +	mask = PCIE_DIRECT_LINK_WIDTH_CHANGE | PCIE_TARGET_LINK_WIDTH;
>>>>>> +	val = PCIE_DIRECT_LINK_WIDTH_CHANGE | lpp->lanes;
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, mask, val, PCIE_MULTI_LANE_CTRL);
>>>>> Is this identical functionality to the writing of PCIE_PORT_LINK_CONTROL
>>>>> in dw_pcie_setup?
>>>>>
>>>>> I ask because if the user sets num-lanes in the DT, will it have the
>>>>> desired effect?
>>>> intel_pcie_max_link_width_setup() function will be called by sysfs attribute pcie_width_store() to change on the fly.
>>> Indeed, but a user may also set num-lanes in the device tree. I'm wondering
>>> if, when set in device-tree, it will have the desired effect. Because I don't
>>> see anything similar to PCIE_LCTLSTS_HW_AW_DIS in dw_pcie_setup which is what
>>> your function does here.
>>>
>>> I guess I'm trying to avoid the suitation where num-lanes doesn't have the
>>> desired effect and the only way to set the num-lanes is throught the sysfs
>>> control.
>> I will check this and get back to you.
intel_pcie_max_link_width_setup() is doing the lane resizing which is 
different from the link up/establishment during the probe. Also 
PCIE_LCTLSTS_HW_AW_DIS default value is 0 so not configuring during the 
probe or dw_pcie_setup()

intel_pcie_max_link_width_setup() is following the Designware databook 
instructions for lane resizing and below is the snippet from the book.

Program the TARGET_LINK_WIDTH[5:0] field of the MULTI_LANE_CONTROL_OFF 
register.
Program the DIRECT_LINK_WIDTH_CHANGE field of MULTI_LANE_CONTROL_OFF 
register.
It is assumed that the PCIE_CAP_HW_AUTO_WIDTH_DISABLE field in the 
LINK_CONTROL_LINK_STATUS_REG register is 0.
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_port_logic_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 val, mask, fts;
>>>>>> +
>>>>>> +	switch (lpp->max_speed) {
>>>>>> +	case PCIE_LINK_SPEED_GEN1:
>>>>>> +	case PCIE_LINK_SPEED_GEN2:
>>>>>> +		fts = PCIE_AFR_GEN12_FTS_NUM_DFT;
>>>>>> +		break;
>>>>>> +	case PCIE_LINK_SPEED_GEN3:
>>>>>> +		fts = PCIE_AFR_GEN3_FTS_NUM_DFT;
>>>>>> +		break;
>>>>>> +	case PCIE_LINK_SPEED_GEN4:
>>>>>> +		fts = PCIE_AFR_GEN4_FTS_NUM_DFT;
>>>>>> +		break;
>>>>>> +	default:
>>>>>> +		fts = PCIE_AFR_GEN12_FTS_NUM_DFT;
>>>>>> +		break;
>>>>>> +	}
>>>>>> +	mask = PCIE_AFR_FTS_NUM | PCIE_AFR_COM_FTS_NUM;
>>>>>> +	val = FIELD_PREP(PCIE_AFR_FTS_NUM, fts) |
>>>>>> +	       FIELD_PREP(PCIE_AFR_COM_FTS_NUM, fts);
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, mask, val, PCIE_AFR);
>>>>>> +
>>>>>> +	/* Port Link Control Register */
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PCIE_PLCR_DLL_LINK_EN,
>>>>>> +			    PCIE_PLCR_DLL_LINK_EN, PCIE_PORT_LINK_CONTROL);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_upconfig_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PCIE_UPCONFIG_SUPPORT,
>>>>>> +			    PCIE_UPCONFIG_SUPPORT, PCIE_MULTI_LANE_CTRL);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_rc_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	intel_pcie_ltssm_disable(lpp);
>>>>>> +	intel_pcie_link_setup(lpp);
>>>>>> +	dw_pcie_setup_rc(&lpp->pci.pp);
>>>>>> +	intel_pcie_upconfig_setup(lpp);
>>>>>> +
>>>>>> +	intel_pcie_max_speed_setup(lpp);
>>>>>> +	intel_pcie_speed_change_enable(lpp);
>>>>>> +	intel_pcie_port_logic_setup(lpp);
>>>>>> +	intel_pcie_mem_iatu(lpp);
>>>>> Doesn't dw_pcie_setup_rc do the same as intel_pcie_mem_iatu?
>>>> Thanks for pointing it. dw_pcie_setup_rc() does.
>>>> intel_pcie_mem_iatu can be removed.
>>> Excellent.
>>>
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_ep_rst_init(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	struct device *dev = lpp->pci.dev;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	lpp->reset_gpio = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
>>>>>> +	if (IS_ERR(lpp->reset_gpio)) {
>>>>>> +		ret = PTR_ERR(lpp->reset_gpio);
>>>>>> +		if (ret != -EPROBE_DEFER)
>>>>>> +			dev_err(dev, "failed to request PCIe GPIO: %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +	/* Make initial reset last for 100us */
>>>>>> +	usleep_range(100, 200);
>>>>>> +
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_core_rst_assert(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	reset_control_assert(lpp->core_rst);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_core_rst_deassert(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	/*
>>>>>> +	 * One micro-second delay to make sure the reset pulse
>>>>>> +	 * wide enough so that core reset is clean.
>>>>>> +	 */
>>>>>> +	udelay(1);
>>>>>> +	reset_control_deassert(lpp->core_rst);
>>>>>> +
>>>>>> +	/*
>>>>>> +	 * Some SoC core reset also reset PHY, more delay needed
>>>>>> +	 * to make sure the reset process is done.
>>>>>> +	 */
>>>>>> +	usleep_range(1000, 2000);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_device_rst_assert(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	gpiod_set_value_cansleep(lpp->reset_gpio, 1);
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_device_rst_deassert(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	msleep(lpp->rst_interval);
>>>>>> +	gpiod_set_value_cansleep(lpp->reset_gpio, 0);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_app_logic_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	intel_pcie_device_rst_deassert(lpp);
>>>>>> +	intel_pcie_ltssm_enable(lpp);
>>>>>> +
>>>>>> +	return dw_pcie_wait_for_link(&lpp->pci);
>>>>>> +}
>>>>>> +
>>>>>> +static irqreturn_t intel_pcie_core_isr(int irq, void *arg)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp = arg;
>>>>>> +	u32 val, reg;
>>>>>> +
>>>>>> +	reg = pcie_app_rd(lpp, PCIE_APP_IRNCR);
>>>>>> +	val = reg & PCIE_APP_IRN_INT;
>>>>>> +
>>>>>> +	pcie_app_wr(lpp, val, PCIE_APP_IRNCR);
>>>>>> +
>>>>>> +	trace_printk("PCIe misc interrupt status 0x%x\n", reg);
>>>>>> +	return IRQ_HANDLED;
>>>>>> +}
>>>>> Why do we bother handling this interrupt?
>>>> This helps during debugging.
>>> I think it should be removed. It adds very little value to most users.
>>>
>>> Most users won't have access to the datasheets to debug this properly, and
>>> in any case if they could, then they would be competent to add an interrupt
>>> handler themselves.
>> IMO, having this will help to get the basic hardware interrupt status during
>> debugging.
>> And, user also can enhance the handler as per the need.
>> I thing keeping it is beneficial than removing it.
>> Please let me know your view.
> I'm much prefer to remove this.
Sure, i am OK to remove it.
>
>>>>>> +
>>>>>> +static int intel_pcie_setup_irq(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	struct device *dev = lpp->pci.dev;
>>>>>> +	struct platform_device *pdev;
>>>>>> +	char *irq_name;
>>>>>> +	int irq, ret;
>>>>>> +
>>>>>> +	pdev = to_platform_device(dev);
>>>>>> +	irq = platform_get_irq(pdev, 0);
>>>>>> +	if (irq < 0) {
>>>>>> +		dev_err(dev, "missing sys integrated irq resource\n");
>>>>>> +		return irq;
>>>>>> +	}
>>>>>> +
>>>>>> +	irq_name = devm_kasprintf(dev, GFP_KERNEL, "pcie_misc%d", lpp->id);
>>>>>> +	if (!irq_name) {
>>>>>> +		dev_err(dev, "failed to alloc irq name\n");
>>>>>> +		return -ENOMEM;
>>>>>> +	}
>>>>>> +
>>>>>> +	ret = devm_request_irq(dev, irq, intel_pcie_core_isr,
>>>>>> +			       IRQF_SHARED, irq_name, lpp);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(dev, "request irq %d failed\n", irq);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +	/* Enable integrated interrupts */
>>>>>> +	pcie_app_wr_mask(lpp, PCIE_APP_IRN_INT,
>>>>>> +			 PCIE_APP_IRN_INT, PCIE_APP_IRNEN);
>>>>>> +
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_core_irq_disable(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_app_wr(lpp, 0, PCIE_APP_IRNEN);
>>>>>> +	pcie_app_wr(lpp, PCIE_APP_IRN_INT,  PCIE_APP_IRNCR);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_get_resources(struct platform_device *pdev)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp;
>>>>>> +	struct resource *res;
>>>>>> +	struct dw_pcie *pci;
>>>>>> +	struct device *dev;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	lpp = platform_get_drvdata(pdev);
>>>>>> +	pci = &lpp->pci;
>>>>>> +	dev = pci->dev;
>>>>>> +
>>>>>> +	ret = device_property_read_u32(dev, "linux,pci-domain", &lpp->id);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(dev, "failed to get domain id, errno %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
>>>>>> +	if (!res)
>>>>>> +		return -ENXIO;
>>>>>> +
>>>>>> +	pci->dbi_base = devm_ioremap_resource(dev, res);
>>>>>> +	if (IS_ERR(pci->dbi_base))
>>>>>> +		return PTR_ERR(pci->dbi_base);
>>>>>> +
>>>>>> +	lpp->core_clk = devm_clk_get(dev, NULL);
>>>>>> +	if (IS_ERR(lpp->core_clk)) {
>>>>>> +		ret = PTR_ERR(lpp->core_clk);
>>>>>> +		if (ret != -EPROBE_DEFER)
>>>>>> +			dev_err(dev, "failed to get clks: %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	lpp->core_rst = devm_reset_control_get(dev, NULL);
>>>>>> +	if (IS_ERR(lpp->core_rst)) {
>>>>>> +		ret = PTR_ERR(lpp->core_rst);
>>>>>> +		if (ret != -EPROBE_DEFER)
>>>>>> +			dev_err(dev, "failed to get resets: %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	ret = device_property_match_string(dev, "device_type", "pci");
>>>>>> +	if (ret) {
>>>>>> +		dev_err(dev, "failed to find pci device type: %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +
>>>>>> +	if (device_property_read_u32(dev, "reset-assert-ms",
>>>>>> +				     &lpp->rst_interval))
>>>>>> +		lpp->rst_interval = RST_INTRVL_DFT_MS;
>>>>>> +
>>>>>> +	if (device_property_read_u32(dev, "max-link-speed", &lpp->link_gen))
>>>>>> +		lpp->link_gen = 0; /* Fallback to auto */
>>>>> Is it possible to use of_pci_get_max_link_speed here instead?
>>>> Thanks for pointing it. of_pci_get_max_link_speed() can be used here. I will
>>>> update it in the next patch revision.
I just remember, earlier we were using of_pci_get_max_link_speed() 
itself. As per reviewer comments changed it to 
device_property_read_u32() to maintain symmetry in parsing device tree 
properties( from device node).
Let me know your view.
>>>>>> +
>>>>>> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "app");
>>>>>> +	if (!res)
>>>>>> +		return -ENXIO;
>>>>>> +
>>>>>> +	lpp->app_base = devm_ioremap_resource(dev, res);
>>>>>> +	if (IS_ERR(lpp->app_base))
>>>>>> +		return PTR_ERR(lpp->app_base);
>>>>>> +
>>>>>> +	ret = intel_pcie_ep_rst_init(lpp);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>> Given that this is called from a function '..._get_resources' I don't think
>>>>> we should be resetting anything here.
>>>> Agree. I will move it out of get_resources().
>>>>>> +
>>>>>> +	lpp->phy = devm_phy_get(dev, "pciephy");
>>>>>> +	if (IS_ERR(lpp->phy)) {
>>>>>> +		ret = PTR_ERR(lpp->phy);
>>>>>> +		if (ret != -EPROBE_DEFER)
>>>>>> +			dev_err(dev, "couldn't get pcie-phy: %d\n", ret);
>>>>>> +		return ret;
>>>>>> +	}
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_deinit_phy(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	phy_exit(lpp->phy);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_wait_l2(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	u32 value;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	if (lpp->max_speed < PCIE_LINK_SPEED_GEN3)
>>>>>> +		return 0;
>>>>>> +
>>>>>> +	/* Send PME_TURN_OFF message */
>>>>>> +	pcie_app_wr_mask(lpp, PCIE_APP_MSG_XMT_PM_TURNOFF,
>>>>>> +			 PCIE_APP_MSG_XMT_PM_TURNOFF, PCIE_APP_MSG_CR);
>>>>>> +
>>>>>> +	/* Read PMC status and wait for falling into L2 link state */
>>>>>> +	ret = readl_poll_timeout(lpp->app_base + PCIE_APP_PMC, value,
>>>>>> +				 (value & PCIE_APP_PMC_IN_L2), 20,
>>>>>> +				 jiffies_to_usecs(5 * HZ));
>>>>>> +	if (ret)
>>>>>> +		dev_err(lpp->pci.dev, "PCIe link enter L2 timeout!\n");
>>>>>> +
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static void intel_pcie_turn_off(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	if (dw_pcie_link_up(&lpp->pci))
>>>>>> +		intel_pcie_wait_l2(lpp);
>>>>>> +
>>>>>> +	/* Put EP in reset state */
>>>>> EP?
>>>> End point device. I will update it.
>>> Is this not a host bridge controller?
>> It is PERST#, signals hardware reset to the End point .
>>          /* Put EP in reset state */
>>          intel_pcie_device_rst_assert(lpp);
> OK.
>
>>>>>> +	intel_pcie_device_rst_assert(lpp);
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PCI_COMMAND_MEMORY, 0, PCI_COMMAND);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_host_setup(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	intel_pcie_core_rst_assert(lpp);
>>>>>> +	intel_pcie_device_rst_assert(lpp);
>>>>>> +
>>>>>> +	ret = phy_init(lpp->phy);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>>> +
>>>>>> +	intel_pcie_core_rst_deassert(lpp);
>>>>>> +
>>>>>> +	ret = clk_prepare_enable(lpp->core_clk);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(lpp->pci.dev, "Core clock enable failed: %d\n", ret);
>>>>>> +		goto clk_err;
>>>>>> +	}
>>>>>> +
>>>>>> +	intel_pcie_rc_setup(lpp);
>>>>>> +	ret = intel_pcie_app_logic_setup(lpp);
>>>>>> +	if (ret)
>>>>>> +		goto app_init_err;
>>>>>> +
>>>>>> +	ret = intel_pcie_setup_irq(lpp);
>>>>>> +	if (!ret)
>>>>>> +		return ret;
>>>>>> +
>>>>>> +	intel_pcie_turn_off(lpp);
>>>>>> +app_init_err:
>>>>>> +	clk_disable_unprepare(lpp->core_clk);
>>>>>> +clk_err:
>>>>>> +	intel_pcie_core_rst_assert(lpp);
>>>>>> +	intel_pcie_deinit_phy(lpp);
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static ssize_t
>>>>>> +pcie_link_status_show(struct device *dev, struct device_attribute *attr,
>>>>>> +		      char *buf)
>>>>>> +{
>>>>>> +	u32 reg, width, gen;
>>>>>> +	struct intel_pcie_port *lpp;
>>>>>> +
>>>>>> +	lpp = dev_get_drvdata(dev);
>>>>>> +
>>>>>> +	reg = pcie_rc_cfg_rd(lpp, PCIE_LCTLSTS);
>>>>>> +	width = FIELD_GET(PCIE_LCTLSTS_NEGOTIATED_LINK_WIDTH, reg);
>>>>>> +	gen = FIELD_GET(PCIE_LCTLSTS_LINK_SPEED, reg);
>>>>>> +	if (gen > lpp->max_speed)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	return sprintf(buf, "Port %2u Width x%u Speed %s GT/s\n", lpp->id,
>>>>>> +		       width, pcie_link_gen_to_str(gen));
>>>>>> +}
>>>>>> +static DEVICE_ATTR_RO(pcie_link_status);
>>>>>> +
>>>>>> +static ssize_t pcie_speed_store(struct device *dev,
>>>>>> +				struct device_attribute *attr,
>>>>>> +				const char *buf, size_t len)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp;
>>>>>> +	unsigned long val;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	lpp = dev_get_drvdata(dev);
>>>>>> +
>>>>>> +	ret = kstrtoul(buf, 10, &val);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>>> +
>>>>>> +	if (val > lpp->max_speed)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	lpp->link_gen = val;
>>>>>> +	intel_pcie_max_speed_setup(lpp);
>>>>>> +	intel_pcie_speed_change_disable(lpp);
>>>>>> +	intel_pcie_speed_change_enable(lpp);
>>>>>> +
>>>>>> +	return len;
>>>>>> +}
>>>>>> +static DEVICE_ATTR_WO(pcie_speed);
>>>>>> +
>>>>>> +/*
>>>>>> + * Link width change on the fly is not always successful.
>>>>>> + * It also depends on the partner.
>>>>>> + */
>>>>>> +static ssize_t pcie_width_store(struct device *dev,
>>>>>> +				struct device_attribute *attr,
>>>>>> +				const char *buf, size_t len)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp;
>>>>>> +	unsigned long val;
>>>>>> +
>>>>>> +	lpp = dev_get_drvdata(dev);
>>>>>> +
>>>>>> +	if (kstrtoul(buf, 10, &val))
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	if (val > lpp->max_width)
>>>>>> +		return -EINVAL;
>>>>>> +
>>>>>> +	lpp->lanes = val;
>>>>>> +	intel_pcie_max_link_width_setup(lpp);
>>>>>> +
>>>>>> +	return len;
>>>>>> +}
>>>>>> +static DEVICE_ATTR_WO(pcie_width);
>>>>> You mentioned that a use-case for changing width/speed on the fly was to
>>>>> control power consumption (and this also helps debugging issues). As I
>>>>> understand there is no current support for this in the kernel - yet it is
>>>>> something that would provide value.
>>>>>
>>>>> I haven't looked in much detail, however as I understand the PCI spec
>>>>> allows an upstream partner to change the link speed and retrain. (I'm not
>>>>> sure about link width). Given that we already have
>>>>> [current,max]_link_[speed,width] is sysfs for each PCI device, it would
>>>>> seem natural to extend this to allow for writing a max width or speed.
>>>>>
>>>>> So ideally this type of thing would be moved to the core or at least in
>>>>> the dwc driver. This way the benefits can be applied to more devices on
>>>>> larger PCI fabrics - Though perhaps others here will have a different view
>>>>> and I'm keen to hear them.
>>>>>
>>>>> I'm keen to limit the differences between the DWC controller drivers and
>>>>> unify common code - thus it would be helpful to have a justification as to
>>>>> why this is only relevant for this controller.
>>>>>
>>>>> For user-space only control, it is possible to achieve what you have here
>>>>> with userspace utilities (something like setpci) (assuming the standard
>>>>> looking registers you currently access are exposed in the normal config
>>>>> space way - though PCIe capabilities).
>>>>>
>>>>> My suggestion would be to drop these changes and later add something that
>>>>> can benefit more devices. In any case if these changes stay within this
>>>>> driver then it would be helpful to move them to a separate patch.
>>>> Sure, i will submit these entity in separate patch.
>>> Please ensure that all supporting macros, functions and defines go with that
>>> other patch as well please.
>> Sure.
>>>>>> +
>>>>>> +static struct attribute *pcie_cfg_attrs[] = {
>>>>>> +	&dev_attr_pcie_link_status.attr,
>>>>>> +	&dev_attr_pcie_speed.attr,
>>>>>> +	&dev_attr_pcie_width.attr,
>>>>>> +	NULL,
>>>>>> +};
>>>>>> +ATTRIBUTE_GROUPS(pcie_cfg);
>>>>>> +
>>>>>> +static int intel_pcie_sysfs_init(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	return devm_device_add_groups(lpp->pci.dev, pcie_cfg_groups);
>>>>>> +}
>>>>>> +
>>>>>> +static void __intel_pcie_remove(struct intel_pcie_port *lpp)
>>>>>> +{
>>>>>> +	pcie_rc_cfg_wr_mask(lpp, PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER,
>>>>>> +			    0, PCI_COMMAND);
>>>>>> +	intel_pcie_core_irq_disable(lpp);
>>>>>> +	intel_pcie_turn_off(lpp);
>>>>>> +	clk_disable_unprepare(lpp->core_clk);
>>>>>> +	intel_pcie_core_rst_assert(lpp);
>>>>>> +	intel_pcie_deinit_phy(lpp);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_remove(struct platform_device *pdev)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp = platform_get_drvdata(pdev);
>>>>>> +	struct pcie_port *pp = &lpp->pci.pp;
>>>>>> +
>>>>>> +	dw_pcie_host_deinit(pp);
>>>>>> +	__intel_pcie_remove(lpp);
>>>>>> +
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>> +static int __maybe_unused intel_pcie_suspend_noirq(struct device *dev)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp = dev_get_drvdata(dev);
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	intel_pcie_core_irq_disable(lpp);
>>>>>> +	ret = intel_pcie_wait_l2(lpp);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>>> +
>>>>>> +	intel_pcie_deinit_phy(lpp);
>>>>>> +	clk_disable_unprepare(lpp->core_clk);
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static int __maybe_unused intel_pcie_resume_noirq(struct device *dev)
>>>>>> +{
>>>>>> +	struct intel_pcie_port *lpp = dev_get_drvdata(dev);
>>>>>> +
>>>>>> +	return intel_pcie_host_setup(lpp);
>>>>>> +}
>>>>>> +
>>>>>> +static int intel_pcie_rc_init(struct pcie_port *pp)
>>>>>> +{
>>>>>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>>>>>> +	struct intel_pcie_port *lpp = dev_get_drvdata(pci->dev);
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	/* RC/host initialization */
>>>>>> +	ret = intel_pcie_host_setup(lpp);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>> Insert new line here.
>>>> Ok.
>>>>>> +	ret = intel_pcie_sysfs_init(lpp);
>>>>>> +	if (ret)
>>>>>> +		__intel_pcie_remove(lpp);
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +int intel_pcie_msi_init(struct pcie_port *pp)
>>>>>> +{
>>>>>> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>>>>>> +
>>>>>> +	dev_dbg(pci->dev, "PCIe MSI/MSIx is handled by MSI in x86 processor\n");
>>>>> What about other processors? (Noting that this driver doesn't depend on
>>>>> any specific ARCH in the KConfig).
>>>> Agree. i will mark the dependency in Kconfig.
>>> OK, please also see how other drivers use the COMPILE_TEST Kconfig option.
>> Ok sure.
>>> I'd suggest that the dev_dbg just becomes a code comment.
Ok
>>>
>>>>>> +	return 0;
>>>>>> +}
>>>>>> +
>>>>>> +u64 intel_pcie_cpu_addr(struct dw_pcie *pcie, u64 cpu_addr)
>>>>>> +{
>>>>>> +	return cpu_addr + BUS_IATU_OFFS;
>>>>>> +}
>>>>>> +
>>>>>> +static const struct dw_pcie_ops intel_pcie_ops = {
>>>>>> +	.cpu_addr_fixup = intel_pcie_cpu_addr,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct dw_pcie_host_ops intel_pcie_dw_ops = {
>>>>>> +	.host_init =		intel_pcie_rc_init,
>>>>>> +	.msi_host_init =	intel_pcie_msi_init,
>>>>>> +};
>>>>>> +
>>>>>> +static const struct intel_pcie_soc pcie_data = {
>>>>>> +	.pcie_ver =		0x520A,
>>>>>> +	.pcie_atu_offset =	0xC0000,
>>>>>> +	.num_viewport =		3,
>>>>>> +};
>>>>>> +
>>>>>> +static int intel_pcie_probe(struct platform_device *pdev)
>>>>>> +{
>>>>>> +	const struct intel_pcie_soc *data;
>>>>>> +	struct device *dev = &pdev->dev;
>>>>>> +	struct intel_pcie_port *lpp;
>>>>>> +	struct pcie_port *pp;
>>>>>> +	struct dw_pcie *pci;
>>>>>> +	int ret;
>>>>>> +
>>>>>> +	lpp = devm_kzalloc(dev, sizeof(*lpp), GFP_KERNEL);
>>>>>> +	if (!lpp)
>>>>>> +		return -ENOMEM;
>>>>>> +
>>>>>> +	platform_set_drvdata(pdev, lpp);
>>>>>> +	pci = &lpp->pci;
>>>>>> +	pci->dev = dev;
>>>>>> +	pp = &pci->pp;
>>>>>> +
>>>>>> +	ret = intel_pcie_get_resources(pdev);
>>>>>> +	if (ret)
>>>>>> +		return ret;
>>>>>> +
>>>>>> +	data = device_get_match_data(dev);
>>>>>> +	pci->ops = &intel_pcie_ops;
>>>>>> +	pci->version = data->pcie_ver;
>>>>>> +	pci->atu_base = pci->dbi_base + data->pcie_atu_offset;
>>>>>> +	pp->ops = &intel_pcie_dw_ops;
>>>>>> +
>>>>>> +	ret = dw_pcie_host_init(pp);
>>>>>> +	if (ret) {
>>>>>> +		dev_err(dev, "cannot initialize host\n");
>>>>>> +		return ret;
>>>>>> +	}
>>>>> Add a new line after the closing brace.
>>>> Ok
>>>>>> +	/* Intel PCIe doesn't configure IO region, so configure
>>>>>> +	 * viewport to not to access IO region during register
>>>>>> +	 * read write operations.
>>>>>> +	 */
>>>>>> +	pci->num_viewport = data->num_viewport;
>>>>>> +	dev_info(dev,
>>>>>> +		 "Intel AXI PCIe Root Complex Port %d Init Done\n", lpp->id);
>>>>>> +	return ret;
>>>>>> +}
>>>>>> +
>>>>>> +static const struct dev_pm_ops intel_pcie_pm_ops = {
>>>>>> +	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(intel_pcie_suspend_noirq,
>>>>>> +				      intel_pcie_resume_noirq)
>>>>>> +};
>>>>>> +
>>>>>> +static const struct of_device_id of_intel_pcie_match[] = {
>>>>>> +	{ .compatible = "intel,lgm-pcie", .data = &pcie_data },
>>>>>> +	{}
>>>>>> +};
>>>>>> +
>>>>>> +static struct platform_driver intel_pcie_driver = {
>>>>>> +	.probe = intel_pcie_probe,
>>>>>> +	.remove = intel_pcie_remove,
>>>>>> +	.driver = {
>>>>>> +		.name = "intel-lgm-pcie",
>>>>> Is there a reason why the we use intel-lgm-pcie here and pcie-intel-axi
>>>>> elsewhere? What does lgm mean?
>>>> lgm is the name of intel SoC.  I will name it to pcie-intel-axi to be
>>>> generic.
>>> I'm keen to ensure that it is consistently named. I've seen other comments
>>> regarding what the name should be - I don't have a strong opinion though
>>> I do think that *-axi may be too generic.
>> Ok, i will check and get back to you on this.

This Driver is for PCIe RC controller on Intel Gateway SoCs. So how 
about naming it as "pcie-intel-gw"; pcie-intel-gw.c; PCIE_INTEL_GW in 
Kconfig.
Let me know your view.

Regards,
Dilip

>>
>> Regards,
> Thanks,
>
> Andrew Murray
>
>> Dilip
>>
>>> Thanks,
>>>
>>> Andrew Murray
>>>
>>>>> Thanks,
>>>>>
>>>>> Andrew Murray
>>>>>
>>>>>> +		.of_match_table = of_intel_pcie_match,
>>>>>> +		.pm = &intel_pcie_pm_ops,
>>>>>> +	},
>>>>>> +};
>>>>>> +builtin_platform_driver(intel_pcie_driver);
>>>>>> -- 
>>>>>> 2.11.0
>>>>>>