[PATCH v4] PCI: j721e: Delay T_PVPERL+TPERST_CLK before PERST# inactive
From: Achal Verma <hidden>
Date: 2023-08-12 19:28:17
Also in:
linux-omap, linux-pci, lkml
Subsystem:
pci driver for cadence pcie ip, pci driver for ti dra7xx/j721e, pci native host bridge and endpoint drivers, pci subsystem, the rest · Maintainers:
Vignesh Raghavendra, Lorenzo Pieralisi, Krzysztof Wilczyński, Manivannan Sadhasivam, Bjorn Helgaas, Linus Torvalds
As per the PCIe Card Electromechanical specification REV. 5.0, PERST#
signal should be de-asserted after minimum 100ms from the time power-rails
achieve specified operating limits and 100us after reference clock gets
stable.
From PCIe Card Electromechanical specification REV. 5.0 section 2.9.2:
TPVPERL: Power stable to PERST# inactive - 100ms
TPERST_CLK: REFCLK stable before PERST# inactive - 100us
Fixes: f3e25911a430 ("PCI: j721e: Add TI J721E PCIe driver")
Signed-off-by: Achal Verma <redacted>
---
drivers/pci/controller/cadence/pci-j721e.c | 29 +++++++++++-----------
drivers/pci/pci.h | 3 +++
2 files changed, 17 insertions(+), 15 deletions(-)
diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index 2c87e7728a65..2c3b3af59271 100644
--- a/drivers/pci/controller/cadence/pci-j721e.c
+++ b/drivers/pci/controller/cadence/pci-j721e.c@@ -34,6 +34,8 @@ #define J721E_PCIE_USER_LINKSTATUS 0x14 #define LINK_STATUS GENMASK(1, 0) +#define PERST_INACTIVE_US (PCIE_TPVPERL_MS*USEC_PER_MSEC + PCIE_TPERST_CLK_US) + enum link_status { NO_RECEIVERS_DETECTED, LINK_TRAINING_IN_PROGRESS,
@@ -359,7 +361,7 @@ static int j721e_pcie_probe(struct platform_device *pdev) struct j721e_pcie *pcie; struct cdns_pcie_rc *rc = NULL; struct cdns_pcie_ep *ep = NULL; - struct gpio_desc *gpiod; + struct gpio_desc *perst_gpiod; void __iomem *base; struct clk *clk; u32 num_lanes;
@@ -468,11 +470,10 @@ static int j721e_pcie_probe(struct platform_device *pdev) switch (mode) { case PCI_MODE_RC: - gpiod = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_LOW); - if (IS_ERR(gpiod)) { - ret = PTR_ERR(gpiod); - if (ret != -EPROBE_DEFER) - dev_err(dev, "Failed to get reset GPIO\n"); + perst_gpiod = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW); + if (IS_ERR(perst_gpiod)) { + ret = PTR_ERR(perst_gpiod); + dev_err(dev, "Failed to get reset GPIO\n"); goto err_get_sync; }
@@ -498,16 +499,14 @@ static int j721e_pcie_probe(struct platform_device *pdev) /* * "Power Sequencing and Reset Signal Timings" table in - * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 3.0 - * indicates PERST# should be deasserted after minimum of 100us - * once REFCLK is stable. The REFCLK to the connector in RC - * mode is selected while enabling the PHY. So deassert PERST# - * after 100 us. + * PCI EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 5.0 + * indicates PERST# should be deasserted after minimum of 100ms + * after power rails achieve specified operating limits and + * 100us after reference clock gets stable. + * PERST_INACTIVE_US accounts for both delays. */ - if (gpiod) { - usleep_range(100, 200); - gpiod_set_value_cansleep(gpiod, 1); - } + + fsleep(PERST_INACTIVE_US); ret = cdns_pcie_host_setup(rc); if (ret < 0) {
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index a4c397434057..80d520be34e6 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h@@ -13,6 +13,9 @@ #define PCIE_LINK_RETRAIN_TIMEOUT_MS 1000 +#define PCIE_TPVPERL_MS 100 /* see PCIe CEM r5.0, sec 2.9.2 */ +#define PCIE_TPERST_CLK_US 100 + extern const unsigned char pcie_link_speed[]; extern bool pci_early_dump;
--
2.25.1
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