Re: [PATCH 09/10] PCI: tegra: Add Tegra194 PCIe support

Vidya Sagar
2019-04-02T07:18:11Z

On 3/30/2019 2:22 AM, Bjorn Helgaas wrote:
> Hi Vidya,
>
> Wow, there's a lot of nice work here! Thanks for that!
>
> On Tue, Mar 26, 2019 at 08:43:26PM +0530, Vidya Sagar wrote:
>> Add support for Synopsys DesignWare core IP based PCIe host controller
>> present in Tegra194 SoC.
>
> General comments:
>
> - There are a few multi-line comments that don't match the
> prevailing style:
>
> /*
> * Text...
> */
>
> - Comments and dev_info()/dev_err() messages are inconsistent about
> starting with upper-case or lower-case letters.
>
> - Use "MSI", "IRQ", "PCIe", "CPU", etc in comments and messages.
>
> - There are a few functions that use "&pdev->dev" many times; can
> you add a "struct device *dev = &pdev->dev" to reduce the
> redundancy?
Done.

>
>> +#include "../../pcie/portdrv.h"
>
> What's this for? I didn't see any obvious uses of things from
> portdrv.h, but I didn't actually try to build without it.
This is for pcie_pme_disable_msi() API. Since this is defined in portdrv.h
file, I'm including it here.

>
>> +struct tegra_pcie_dw {
>> + struct device *dev;
>> + struct resource *appl_res;
>> + struct resource *dbi_res;
>> + struct resource *atu_dma_res;
>> + void __iomem *appl_base;
>> + struct clk *core_clk;
>> + struct reset_control *core_apb_rst;
>> + struct reset_control *core_rst;
>> + struct dw_pcie pci;
>> + enum dw_pcie_device_mode mode;
>> +
>> + bool disable_clock_request;
>> + bool power_down_en;
>> + u8 init_link_width;
>> + bool link_state;
>> + u32 msi_ctrl_int;
>> + u32 num_lanes;
>> + u32 max_speed;
>> + u32 init_speed;
>> + bool cdm_check;
>> + u32 cid;
>> + int pex_wake;
>> + bool update_fc_fixup;
>> + int n_gpios;
>> + int *gpios;
>> +#if defined(CONFIG_PCIEASPM)
>> + u32 cfg_link_cap_l1sub;
>> + u32 event_cntr_ctrl;
>> + u32 event_cntr_data;
>> + u32 aspm_cmrt;
>> + u32 aspm_pwr_on_t;
>> + u32 aspm_l0s_enter_lat;
>> + u32 disabled_aspm_states;
>> +#endif
>
> The above could be indented the same as the rest of the struct?
Done.

>
>> + struct regulator *pex_ctl_reg;
>> +
>> + int phy_count;
>> + struct phy **phy;
>> +
>> + struct dentry *debugfs;
>> +};
>
>> +static void apply_bad_link_workaround(struct pcie_port *pp)
>> +{
>> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> + struct tegra_pcie_dw *pcie = dw_pcie_to_tegra_pcie(pci);
>> + u16 val;
>> +
>> + /*
>> + * NOTE:- Since this scenario is uncommon and link as
>> + * such is not stable anyway, not waiting to confirm
>> + * if link is really transiting to Gen-2 speed
>
> s/transiting/transitioning/
>
> I think there are other uses of "transit" when you mean "transition".
Done.

>
>> +static int tegra_pcie_dw_rd_own_conf(struct pcie_port *pp, int where, int size,
>> + u32 *val)
>> +{
>> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> +
>> + /*
>> + * This is an endpoint mode specific register happen to appear even
>> + * when controller is operating in root port mode and system hangs
>> + * when it is accessed with link being in ASPM-L1 state.
>> + * So skip accessing it altogether
>> + */
>> + if (where == PORT_LOGIC_MSIX_DOORBELL) {
>> + *val = 0x00000000;
>> + return PCIBIOS_SUCCESSFUL;
>> + } else {
>> + return dw_pcie_read(pci->dbi_base + where, size, val);
>> + }
>> +}
>> +
>> +static int tegra_pcie_dw_wr_own_conf(struct pcie_port *pp, int where, int size,
>> + u32 val)
>> +{
>> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> +
>> + /* This is EP specific register and system hangs when it is
>> + * accessed with link being in ASPM-L1 state.
>> + * So skip accessing it altogether
>> + */
>> + if (where == PORT_LOGIC_MSIX_DOORBELL)
>> + return PCIBIOS_SUCCESSFUL;
>> + else
>> + return dw_pcie_write(pci->dbi_base + where, size, val);
>
> These two functions are almost identical and they could look more
> similar. This one has the wrong multi-line comment style, uses "EP"
> instead of "endpoint", etc. Use this style for the "if" since the
> first case is really an error case:
>
> if (where == PORT_LOGIC_MSIX_DOORBELL) {
> ...
> return ...;
> }
>
> return dw_pcie_...();
Done.

>
>> +static int tegra_pcie_dw_host_init(struct pcie_port *pp)
>> +{
>> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> + struct tegra_pcie_dw *pcie = dw_pcie_to_tegra_pcie(pci);
>> + int count = 200;
>> + u32 val, tmp, offset;
>> + u16 val_w;
>> +
>> +#if defined(CONFIG_PCIEASPM)
>> + pcie->cfg_link_cap_l1sub =
>> + dw_pcie_find_ext_capability(pci, PCI_EXT_CAP_ID_L1SS) +
>> + PCI_L1SS_CAP;
>> +#endif
>> + val = dw_pcie_readl_dbi(pci, PCI_IO_BASE);
>> + val &= ~(IO_BASE_IO_DECODE | IO_BASE_IO_DECODE_BIT8);
>> + dw_pcie_writel_dbi(pci, PCI_IO_BASE, val);
>> +
>> + val = dw_pcie_readl_dbi(pci, PCI_PREF_MEMORY_BASE);
>> + val |= CFG_PREF_MEM_LIMIT_BASE_MEM_DECODE;
>> + val |= CFG_PREF_MEM_LIMIT_BASE_MEM_LIMIT_DECODE;
>> + dw_pcie_writel_dbi(pci, PCI_PREF_MEMORY_BASE, val);
>> +
>> + dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0);
>> +
>> + /* Configure FTS */
>> + val = dw_pcie_readl_dbi(pci, PORT_LOGIC_ACK_F_ASPM_CTRL);
>> + val &= ~(N_FTS_MASK << N_FTS_SHIFT);
>> + val |= N_FTS_VAL << N_FTS_SHIFT;
>> + dw_pcie_writel_dbi(pci, PORT_LOGIC_ACK_F_ASPM_CTRL, val);
>> +
>> + val = dw_pcie_readl_dbi(pci, PORT_LOGIC_GEN2_CTRL);
>> + val &= ~FTS_MASK;
>> + val |= FTS_VAL;
>> + dw_pcie_writel_dbi(pci, PORT_LOGIC_GEN2_CTRL, val);
>> +
>> + /* Enable as 0xFFFF0001 response for CRS */
>> + val = dw_pcie_readl_dbi(pci, PORT_LOGIC_AMBA_ERROR_RESPONSE_DEFAULT);
>> + val &= ~(AMBA_ERROR_RESPONSE_CRS_MASK << AMBA_ERROR_RESPONSE_CRS_SHIFT);
>> + val |= (AMBA_ERROR_RESPONSE_CRS_OKAY_FFFF0001 <<
>> + AMBA_ERROR_RESPONSE_CRS_SHIFT);
>> + dw_pcie_writel_dbi(pci, PORT_LOGIC_AMBA_ERROR_RESPONSE_DEFAULT, val);
>> +
>> + /* Set MPS to 256 in DEV_CTL */
>> + val = dw_pcie_readl_dbi(pci, CFG_DEV_STATUS_CONTROL);
>> + val &= ~PCI_EXP_DEVCTL_PAYLOAD;
>> + val |= (1 << CFG_DEV_STATUS_CONTROL_MPS_SHIFT);
>> + dw_pcie_writel_dbi(pci, CFG_DEV_STATUS_CONTROL, val);
>> +
>> + /* Configure Max Speed from DT */
>> + val = dw_pcie_readl_dbi(pci, CFG_LINK_CAP);
>> + val &= ~PCI_EXP_LNKCAP_SLS;
>> + val |= pcie->max_speed;
>> + dw_pcie_writel_dbi(pci, CFG_LINK_CAP, val);
>> +
>> + val = dw_pcie_readw_dbi(pci, CFG_LINK_CONTROL_2);
>> + val &= ~PCI_EXP_LNKCTL2_TLS;
>> + val |= pcie->init_speed;
>> + dw_pcie_writew_dbi(pci, CFG_LINK_CONTROL_2, val);
>> +
>> + /* Configure Max lane width from DT */
>> + val = dw_pcie_readl_dbi(pci, CFG_LINK_CAP);
>> + val &= ~PCI_EXP_LNKCAP_MLW;
>> + val |= (pcie->num_lanes << PCI_EXP_LNKSTA_NLW_SHIFT);
>> + dw_pcie_writel_dbi(pci, CFG_LINK_CAP, val);
>> +
>> + config_gen3_gen4_eq_presets(pcie);
>> +
>> +#if defined(CONFIG_PCIEASPM)
>> + /* Enable ASPM counters */
>> + val = EVENT_COUNTER_ENABLE_ALL << EVENT_COUNTER_ENABLE_SHIFT;
>> + val |= EVENT_COUNTER_GROUP_5 << EVENT_COUNTER_GROUP_SEL_SHIFT;
>> + dw_pcie_writel_dbi(pci, pcie->event_cntr_ctrl, val);
>> +
>> + /* Program T_cmrt and T_pwr_on values */
>> + val = dw_pcie_readl_dbi(pci, pcie->cfg_link_cap_l1sub);
>> + val &= ~(PCI_L1SS_CAP_CM_RESTORE_TIME | PCI_L1SS_CAP_P_PWR_ON_VALUE);
>> + val |= (pcie->aspm_cmrt << PCI_L1SS_CAP_CM_RTM_SHIFT);
>> + val |= (pcie->aspm_pwr_on_t << PCI_L1SS_CAP_PWRN_VAL_SHIFT);
>> + dw_pcie_writel_dbi(pci, pcie->cfg_link_cap_l1sub, val);
>> +
>> + /* Program L0s and L1 entrance latencies */
>> + val = dw_pcie_readl_dbi(pci, PORT_LOGIC_ACK_F_ASPM_CTRL);
>> + val &= ~L0S_ENTRANCE_LAT_MASK;
>> + val |= (pcie->aspm_l0s_enter_lat << L0S_ENTRANCE_LAT_SHIFT);
>> + val |= ENTER_ASPM;
>> + dw_pcie_writel_dbi(pci, PORT_LOGIC_ACK_F_ASPM_CTRL, val);
>> +
>> + /* Program what ASPM states sould get advertised */
>
> s/sould/should/
Done.

>
>> + if (pcie->disabled_aspm_states & 0x1)
>> + disable_aspm_l0s(pcie); /* Disable L0s */
>> + if (pcie->disabled_aspm_states & 0x2) {
>> + disable_aspm_l10(pcie); /* Disable L1 */
>> + disable_aspm_l11(pcie); /* Disable L1.1 */
>> + disable_aspm_l12(pcie); /* Disable L1.2 */
>> + }
>> + if (pcie->disabled_aspm_states & 0x4)
>> + disable_aspm_l11(pcie); /* Disable L1.1 */
>> + if (pcie->disabled_aspm_states & 0x8)
>> + disable_aspm_l12(pcie); /* Disable L1.2 */
>> +#endif
>> + val = dw_pcie_readl_dbi(pci, GEN3_RELATED_OFF);
>> + val &= ~GEN3_RELATED_OFF_GEN3_ZRXDC_NONCOMPL;
>> + dw_pcie_writel_dbi(pci, GEN3_RELATED_OFF, val);
>> +
>> + if (pcie->update_fc_fixup) {
>> + val = dw_pcie_readl_dbi(pci, CFG_TIMER_CTRL_MAX_FUNC_NUM_OFF);
>> + val |= 0x1 << CFG_TIMER_CTRL_ACK_NAK_SHIFT;
>> + dw_pcie_writel_dbi(pci, CFG_TIMER_CTRL_MAX_FUNC_NUM_OFF, val);
>> + }
>> +
>> + /* CDM check enable */
>> + if (pcie->cdm_check) {
>> + val = dw_pcie_readl_dbi(pci,
>> + PORT_LOGIC_PL_CHK_REG_CONTROL_STATUS);
>> + val |= PORT_LOGIC_PL_CHK_REG_CHK_REG_CONTINUOUS;
>> + val |= PORT_LOGIC_PL_CHK_REG_CHK_REG_START;
>> + dw_pcie_writel_dbi(pci, PORT_LOGIC_PL_CHK_REG_CONTROL_STATUS,
>> + val);
>> + }
>> +
>> + dw_pcie_setup_rc(pp);
>> +
>> + clk_set_rate(pcie->core_clk, GEN4_CORE_CLK_FREQ);
>> +
>> + /* assert RST */
>> + val = readl(pcie->appl_base + APPL_PINMUX);
>> + val &= ~APPL_PINMUX_PEX_RST;
>> + writel(val, pcie->appl_base + APPL_PINMUX);
>> +
>> + usleep_range(100, 200);
>> +
>> + /* enable LTSSM */
>> + val = readl(pcie->appl_base + APPL_CTRL);
>> + val |= APPL_CTRL_LTSSM_EN;
>> + writel(val, pcie->appl_base + APPL_CTRL);
>> +
>> + /* de-assert RST */
>> + val = readl(pcie->appl_base + APPL_PINMUX);
>> + val |= APPL_PINMUX_PEX_RST;
>> + writel(val, pcie->appl_base + APPL_PINMUX);
>> +
>> + msleep(100);
>> +
>> + val_w = dw_pcie_readw_dbi(pci, CFG_LINK_STATUS);
>> + while (!(val_w & PCI_EXP_LNKSTA_DLLLA)) {
>> + if (!count) {
>> + val = readl(pcie->appl_base + APPL_DEBUG);
>> + val &= APPL_DEBUG_LTSSM_STATE_MASK;
>> + val >>= APPL_DEBUG_LTSSM_STATE_SHIFT;
>> + tmp = readl(pcie->appl_base + APPL_LINK_STATUS);
>> + tmp &= APPL_LINK_STATUS_RDLH_LINK_UP;
>> + if (val == 0x11 && !tmp) {
>> + dev_info(pci->dev, "link is down in DLL");
>> + dev_info(pci->dev,
>> + "trying again with DLFE disabled\n");
>> + /* disable LTSSM */
>> + val = readl(pcie->appl_base + APPL_CTRL);
>> + val &= ~APPL_CTRL_LTSSM_EN;
>> + writel(val, pcie->appl_base + APPL_CTRL);
>> +
>> + reset_control_assert(pcie->core_rst);
>> + reset_control_deassert(pcie->core_rst);
>> +
>> + offset =
>> + dw_pcie_find_ext_capability(pci,
>> + PCI_EXT_CAP_ID_DLF)
>> + + PCI_DLF_CAP;
>
> This capability offset doesn't change, does it? Could it be computed
> outside the loop?
This is the only place where DLF offset is needed and gets calculated and this
scenario is very rare as so far only a legacy ASMedia USB3.0 card requires DLF
to be disabled to get PCIe link up. So, I thought of calculating the offset
here itself instead of using a separate variable.

>
>> + val = dw_pcie_readl_dbi(pci, offset);
>> + val &= ~DL_FEATURE_EXCHANGE_EN;
>> + dw_pcie_writel_dbi(pci, offset, val);
>> +
>> + tegra_pcie_dw_host_init(&pcie->pci.pp);
>
> This looks like some sort of "wait for link up" retry loop, but a
> recursive call seems a little unusual. My 5 second analysis is that
> the loop could run this 200 times, and you sure don't want the
> possibility of a 200-deep call chain. Is there way to split out the
> host init from the link-up polling?
Again, this recursive calling comes into picture only for a legacy ASMedia
USB3.0 card and it is going to be a 1-deep call chain as the recursion takes
place only once depending on the condition. Apart from the legacy ASMedia card,
there is no other card at this point in time out of a huge number of cards that we have
tested.

>
>> + return 0;
>> + }
>> + dev_info(pci->dev, "link is down\n");
>> + return 0;
>> + }
>> + dev_dbg(pci->dev, "polling for link up\n");
>> + usleep_range(1000, 2000);
>> + val_w = dw_pcie_readw_dbi(pci, CFG_LINK_STATUS);
>> + count--;
>> + }
>> + dev_info(pci->dev, "link is up\n");
>> +
>> + tegra_pcie_enable_interrupts(pp);
>> +
>> + return 0;
>> +}
>
>> +static void tegra_pcie_dw_scan_bus(struct pcie_port *pp)
>> +{
>> + struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>> + struct tegra_pcie_dw *pcie = dw_pcie_to_tegra_pcie(pci);
>> + u32 speed;
>> +
>> + if (!tegra_pcie_dw_link_up(pci))
>> + return;
>> +
>> + speed = (dw_pcie_readw_dbi(pci, CFG_LINK_STATUS) & PCI_EXP_LNKSTA_CLS);
>> + clk_set_rate(pcie->core_clk, pcie_gen_freq[speed - 1]);
>
> I don't understand what's happening here. This is named
> tegra_pcie_dw_scan_bus(), but it doesn't actually scan anything.
> Maybe it's just a bad name for the dw_pcie_host_ops hook
> (ks_pcie_v3_65_scan_bus() is the only other .scan_bus()
> implementation, and it doesn't scan anything either).
>
> dw_pcie_host_init() calls pci_scan_root_bus_bridge(), which actually
> *does* scan the bus, but it does it before calling
> pp->ops->scan_bus(). I'd say by the time we get to
> pci_scan_root_bus_bridge(), the device-specific init should be all
> done and we should be using only generic PCI core interfaces.
>
> Maybe this stuff could/should be done in the ->host_init() hook? The
> code between ->host_init() and ->scan_bus() is all generic code with
> no device-specific stuff, so I don't know why we need both hooks.
Agree. At least whatever I'm going here as part of scan_bus can be moved to
host_init() itslef. I'm not sure about the original intention of the scan_bus
but my understanding is that, after PCIe sub-system enumerates all devices, if
something needs to be done, then, probably scan_bus() can be implemented for that.
I had some other code initially which was accessing downstream devices, hence I
implemented scan_bus(), but, now, given all that is gone, I can move this code to
host_init() itself.

>
>> +static int tegra_pcie_enable_phy(struct tegra_pcie_dw *pcie)
>> +{
>> + int phy_count = pcie->phy_count;
>> + int ret;
>> + int i;
>> +
>> + for (i = 0; i < phy_count; i++) {
>> + ret = phy_init(pcie->phy[i]);
>> + if (ret < 0)
>> + goto err_phy_init;
>> +
>> + ret = phy_power_on(pcie->phy[i]);
>> + if (ret < 0) {
>> + phy_exit(pcie->phy[i]);
>> + goto err_phy_power_on;
>> + }
>> + }
>> +
>> + return 0;
>> +
>> + while (i >= 0) {
>> + phy_power_off(pcie->phy[i]);
>> +err_phy_power_on:
>> + phy_exit(pcie->phy[i]);
>> +err_phy_init:
>> + i--;
>> + }
>
> Wow, jumping into the middle of that loop is clever ;) Can't decide
> what I think of it, but it's certainly clever!
>
>> + return ret;
>> +}
>> +
>> +static int tegra_pcie_dw_parse_dt(struct tegra_pcie_dw *pcie)
>> +{
>> + struct device_node *np = pcie->dev->of_node;
>> + int ret;
>> +
>> +#if defined(CONFIG_PCIEASPM)
>> + ret = of_property_read_u32(np, "nvidia,event-cntr-ctrl",
>> + &pcie->event_cntr_ctrl);
>> + if (ret < 0) {
>> + dev_err(pcie->dev, "fail to read event-cntr-ctrl: %d\n", ret);
>> + return ret;
>> + }
>
> The fact that you return error here if DT lacks the
> "nvidia,event-cntr-ctrl" property, but only if CONFIG_PCIEASPM=y,
> means that you have a revlock between the DT and the kernel: if you
> update the kernel to enable CONFIG_PCIEASPM, you may also have to
> update your DT.
>
> Maybe that's OK, but I think it'd be nicer if you always required the
> presence of these properties, even if you only actually *use* them
> when CONFIG_PCIEASPM=y.
Done

>
>> +static int tegra_pcie_dw_probe(struct platform_device *pdev)
>> +{
>> + struct tegra_pcie_dw *pcie;
>> + struct pcie_port *pp;
>> + struct dw_pcie *pci;
>> + struct phy **phy;
>> + struct resource *dbi_res;
>> + struct resource *atu_dma_res;
>> + const struct of_device_id *match;
>> + const struct tegra_pcie_of_data *data;
>> + char *name;
>> + int ret, i;
>> +
>> + pcie = devm_kzalloc(&pdev->dev, sizeof(*pcie), GFP_KERNEL);
>> + if (!pcie)
>> + return -ENOMEM;
>> +
>> + pci = &pcie->pci;
>> + pci->dev = &pdev->dev;
>> + pci->ops = &tegra_dw_pcie_ops;
>> + pp = &pci->pp;
>> + pcie->dev = &pdev->dev;
>> +
>> + match = of_match_device(of_match_ptr(tegra_pcie_dw_of_match),
>> + &pdev->dev);
>> + if (!match)
>> + return -EINVAL;
>
> Logically could be the first thing in the function since it doesn't
> depend on anything.
Done

>
>> + data = (struct tegra_pcie_of_data *)match->data;
>> + pcie->mode = (enum dw_pcie_device_mode)data->mode;
>> +
>> + ret = tegra_pcie_dw_parse_dt(pcie);
>> + if (ret < 0) {
>> + dev_err(pcie->dev, "device tree parsing failed: %d\n", ret);
>> + return ret;
>> + }
>> +
>> + if (gpio_is_valid(pcie->pex_wake)) {
>> + ret = devm_gpio_request(pcie->dev, pcie->pex_wake,
>> + "pcie_wake");
>> + if (ret < 0) {
>> + if (ret == -EBUSY) {
>> + dev_err(pcie->dev,
>> + "pex_wake already in use\n");
>> + pcie->pex_wake = -EINVAL;
>
> This looks strange. "pex_wake == -EINVAL" doesn't look right, and
> you're about to pass it to gpio_direction_input(), which looks wrong.
Done.

>
>> + } else {
>> + dev_err(pcie->dev,
>> + "pcie_wake gpio_request failed %d\n",
>> + ret);
>> + return ret;
>> + }
>> + }
>> +
>> + ret = gpio_direction_input(pcie->pex_wake);
>> + if (ret < 0) {
>> + dev_err(pcie->dev,
>> + "setting pcie_wake input direction failed %d\n",
>> + ret);
>> + return ret;
>> + }
>> + device_init_wakeup(pcie->dev, true);
>> + }
>> +
>> + pcie->pex_ctl_reg = devm_regulator_get(&pdev->dev, "vddio-pex-ctl");
>> + if (IS_ERR(pcie->pex_ctl_reg)) {
>> + dev_err(&pdev->dev, "fail to get regulator: %ld\n",
>> + PTR_ERR(pcie->pex_ctl_reg));
>> + return PTR_ERR(pcie->pex_ctl_reg);
>> + }
>> +
>> + pcie->core_clk = devm_clk_get(&pdev->dev, "core_clk");
>> + if (IS_ERR(pcie->core_clk)) {
>> + dev_err(&pdev->dev, "Failed to get core clock\n");
>> + return PTR_ERR(pcie->core_clk);
>> + }
>> +
>> + pcie->appl_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> + "appl");
>> + if (!pcie->appl_res) {
>> + dev_err(&pdev->dev, "missing appl space\n");
>> + return PTR_ERR(pcie->appl_res);
>> + }
>> + pcie->appl_base = devm_ioremap_resource(&pdev->dev, pcie->appl_res);
>> + if (IS_ERR(pcie->appl_base)) {
>> + dev_err(&pdev->dev, "mapping appl space failed\n");
>> + return PTR_ERR(pcie->appl_base);
>> + }
>> +
>> + pcie->core_apb_rst = devm_reset_control_get(pcie->dev, "core_apb_rst");
>> + if (IS_ERR(pcie->core_apb_rst)) {
>> + dev_err(pcie->dev, "PCIE : core_apb_rst reset is missing\n");
>
> This error message looks different from the others ("PCIE :" prefix).
Done.

>
>> + return PTR_ERR(pcie->core_apb_rst);
>> + }
>> +
>> + phy = devm_kcalloc(pcie->dev, pcie->phy_count, sizeof(*phy),
>> + GFP_KERNEL);
>> + if (!phy)
>> + return PTR_ERR(phy);
>> +
>> + for (i = 0; i < pcie->phy_count; i++) {
>> + name = kasprintf(GFP_KERNEL, "pcie-p2u-%u", i);
>> + if (!name) {
>> + dev_err(pcie->dev, "failed to create p2u string\n");
>> + return -ENOMEM;
>> + }
>> + phy[i] = devm_phy_get(pcie->dev, name);
>> + kfree(name);
>> + if (IS_ERR(phy[i])) {
>> + ret = PTR_ERR(phy[i]);
>> + dev_err(pcie->dev, "phy_get error: %d\n", ret);
>> + return ret;
>> + }
>> + }
>> +
>> + pcie->phy = phy;
>> +
>> + dbi_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dbi");
>> + if (!dbi_res) {
>> + dev_err(&pdev->dev, "missing config space\n");
>> + return PTR_ERR(dbi_res);
>> + }
>> + pcie->dbi_res = dbi_res;
>> +
>> + pci->dbi_base = devm_ioremap_resource(&pdev->dev, dbi_res);
>> + if (IS_ERR(pci->dbi_base)) {
>> + dev_err(&pdev->dev, "mapping dbi space failed\n");
>> + return PTR_ERR(pci->dbi_base);
>> + }
>> +
>> + /* Tegra HW locates DBI2 at a fixed offset from DBI */
>> + pci->dbi_base2 = pci->dbi_base + 0x1000;
>> +
>> + atu_dma_res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
>> + "atu_dma");
>> + if (!atu_dma_res) {
>> + dev_err(&pdev->dev, "missing atu_dma space\n");
>> + return PTR_ERR(atu_dma_res);
>> + }
>> + pcie->atu_dma_res = atu_dma_res;
>> + pci->atu_base = devm_ioremap_resource(&pdev->dev, atu_dma_res);
>> + if (IS_ERR(pci->atu_base)) {
>> + dev_err(&pdev->dev, "mapping atu space failed\n");
>> + return PTR_ERR(pci->atu_base);
>> + }
>> +
>> + pcie->core_rst = devm_reset_control_get(pcie->dev, "core_rst");
>> + if (IS_ERR(pcie->core_rst)) {
>> + dev_err(pcie->dev, "PCIE : core_rst reset is missing\n");
>
> Different message format again.
Done.

>
>> + return PTR_ERR(pcie->core_rst);
>> + }
>> +
>> + pp->irq = platform_get_irq_byname(pdev, "intr");
>> + if (!pp->irq) {
>> + dev_err(pcie->dev, "failed to get intr interrupt\n");
>> + return -ENODEV;
>> + }
>> +
>> + ret = devm_request_irq(&pdev->dev, pp->irq, tegra_pcie_irq_handler,
>> + IRQF_SHARED, "tegra-pcie-intr", pcie);
>> + if (ret) {
>> + dev_err(pcie->dev, "failed to request \"intr\" irq\n");
>
> It'd be nice to include the actual IRQ, i.e., "IRQ %d", pp->irq.
Done.

>
>> + return ret;
>> + }
>> +
>> + platform_set_drvdata(pdev, pcie);
>> +
>> + if (pcie->mode == DW_PCIE_RC_TYPE) {
>> + ret = tegra_pcie_config_rp(pcie);
>> + if (ret == -ENOMEDIUM)
>> + ret = 0;
>> + }
>> +
>> + return ret;
>> +}
>
>> +static void tegra_pcie_downstream_dev_to_D0(struct tegra_pcie_dw *pcie)
>> +{
>> + struct pci_dev *pdev = NULL;
>
> Unnecessary initialization.
Done.

>
>> + struct pci_bus *child;
>> + struct pcie_port *pp = &pcie->pci.pp;
>> +
>> + list_for_each_entry(child, &pp->bus->children, node) {
>> + /* Bring downstream devices to D0 if they are not already in */
>> + if (child->parent == pp->bus) {
>> + pdev = pci_get_slot(child, PCI_DEVFN(0, 0));
>> + pci_dev_put(pdev);
>> + if (!pdev)
>> + break;
>
> I don't really like this dance with iterating over the bus children,
> comparing parent to pp->bus, pci_get_slot(), pci_dev_put(), etc.
>
> I guess the idea is to bring only the directly-downstream devices to
> D0, not to do it for things deeper in the hierarchy?
Yes.

>
> Is this some Tegra-specific wrinkle? I don't think other drivers do
> this.
With Tegra PCIe controller, if the downstream device is in non-D0 states,
link doesn't go into L2 state. We observed this behavior with some of the
devices and the solution would be to bring them to D0 state and then attempt
sending PME_TurnOff message to put the link to L2 state.
Since spec also supports this mechanism (Rev.4.0 Ver.1.0 Page #428), we chose
to implement this.

>
> I see that an earlier patch added "bus" to struct pcie_port. I think
> it would be better to somehow connect to the pci_host_bridge struct.
> Several other drivers already do this; see uses of
> pci_host_bridge_from_priv().
All non-DesignWare based implementations save their private data structure
in 'private' pointer of struct pci_host_bridge and use pci_host_bridge_from_priv()
to get it back. But, DesignWare based implementations save pcie_port in 'sysdata'
and nothing in 'private' pointer. So, I'm not sure if pci_host_bridge_from_priv()
can be used in this case. Please do let me know if you think otherwise.

>
> That would give you the bus, as well as flags like no_ext_tags,
> native_aer, etc, which this driver, being a host bridge driver that's
> responsible for this part of the firmware/OS interface, may
> conceivably need.
>
> Rather than pci_get_slot(), couldn't you iterate over bus->devices and
> just skip the non-PCI_DEVFN(0, 0) devices?
>
>> +
>> + if (pci_set_power_state(pdev, PCI_D0))
>> + dev_err(pcie->dev, "D0 transition failed\n");
>> + }
>> + }
>> +}
Yeah. This seems to be a better method. I'll implement this.

>
>> +static int tegra_pcie_dw_remove(struct platform_device *pdev)
>> +{
>> + struct tegra_pcie_dw *pcie = platform_get_drvdata(pdev);
>> +
>> + if (pcie->mode == DW_PCIE_RC_TYPE) {
>
> Return early if it's not RC and unindent the rest of the function.
Done.

>
>> + if (!pcie->link_state && pcie->power_down_en)
>> + return 0;
>> +
>> + debugfs_remove_recursive(pcie->debugfs);
>> + pm_runtime_put_sync(pcie->dev);
>> + pm_runtime_disable(pcie->dev);
>> + }
>> +
>> + return 0;
>> +}
>
>> +static int tegra_pcie_dw_runtime_suspend(struct device *dev)
>> +{
>> + struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
>> +
>> + tegra_pcie_downstream_dev_to_D0(pcie);
>> +
>> + pci_stop_root_bus(pcie->pci.pp.bus);
>> + pci_remove_root_bus(pcie->pci.pp.bus);
>
> Why are you calling these? No other drivers do this except in their
> .remove() methods. Is there something special about Tegra, or is this
> something the other drivers *should* be doing?
Since this API is called by remove, I'm removing the hierarchy to safely
bring down all the devices. I'll have to re-visit this part as
Jisheng Zhang's patches https://patchwork.kernel.org/project/linux-pci/list/?series=98559
are now approved and I need to verify this part after cherry-picking
Jisheng's changes.

>
>> + tegra_pcie_dw_pme_turnoff(pcie);
>> +
>> + reset_control_assert(pcie->core_rst);
>> + tegra_pcie_disable_phy(pcie);
>> + reset_control_assert(pcie->core_apb_rst);
>> + clk_disable_unprepare(pcie->core_clk);
>> + regulator_disable(pcie->pex_ctl_reg);
>> + config_plat_gpio(pcie, 0);
>> +
>> + if (pcie->cid != CTRL_5)
>> + tegra_pcie_bpmp_set_ctrl_state(pcie, false);
>> +
>> + return 0;
>> +}
>> +
>> +static int tegra_pcie_dw_runtime_resume(struct device *dev)
>> +{
>> + struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
>> + struct dw_pcie *pci = &pcie->pci;
>> + struct pcie_port *pp = &pci->pp;
>> + int ret = 0;
>> +
>> + ret = tegra_pcie_config_controller(pcie, false);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* program to use MPS of 256 whereever possible */
>
> s/whereever/wherever/
Done.

>
>> + pcie_bus_config = PCIE_BUS_SAFE;
>> +
>> + pp->root_bus_nr = -1;
>> + pp->ops = &tegra_pcie_dw_host_ops;
>> +
>> + /* Disable MSI interrupts for PME messages */
>
> Superfluous comment; it repeats the function name.
Removed it.

>
>> +static int tegra_pcie_dw_suspend_noirq(struct device *dev)
>> +{
>> + struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
>> + int ret = 0;
>> +
>> + if (!pcie->link_state)
>> + return 0;
>> +
>> + /* save MSI interrutp vector*/
>
> s/interrutp/interrupt/
> s/vector/vector /
Done.

>
>> +static int tegra_pcie_dw_resume_noirq(struct device *dev)
>> +{
>> + struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
>> + int ret;
>> +
>> + if (!pcie->link_state)
>> + return 0;
>> +
>> + if (gpio_is_valid(pcie->pex_wake) && device_may_wakeup(dev)) {
>> + ret = disable_irq_wake(gpio_to_irq(pcie->pex_wake));
>> + if (ret < 0)
>> + dev_err(dev, "disable wake irq failed: %d\n", ret);
>> + }
>> +
>> + ret = tegra_pcie_config_controller(pcie, true);
>> + if (ret < 0)
>> + return ret;
>> +
>> + ret = tegra_pcie_dw_host_init(&pcie->pci.pp);
>> + if (ret < 0) {
>> + dev_err(dev, "failed to init host: %d\n", ret);
>> + goto fail_host_init;
>> + }
>> +
>> + /* restore MSI interrutp vector*/
>
> s/interrutp/interrupt/
> s/vector/vector /
Done.

>
>> +static void tegra_pcie_dw_shutdown(struct platform_device *pdev)
>> +{
>> + struct tegra_pcie_dw *pcie = platform_get_drvdata(pdev);
>> +
>> + if (pcie->mode == DW_PCIE_RC_TYPE) {
>
> if (pcie->mode != DW_PCIE_RC_TYPE)
> return;
>
> Then you can unindent the whole function.
Done.

>
>> + if (!pcie->link_state && pcie->power_down_en)
>> + return;
>> +
>> + debugfs_remove_recursive(pcie->debugfs);
>> + tegra_pcie_downstream_dev_to_D0(pcie);
>> +
>> + /* Disable interrupts */
>
> Superfluous comment.
Removed it.

>
>> + disable_irq(pcie->pci.pp.irq);