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 <a-verma1@xxxxxx>
---
drivers/pci/controller/cadence/pci-j721e.c | 30 +++++++++++-----------
drivers/pci/pci.h | 3 +++
2 files changed, 18 insertions(+), 15 deletions(-)
diff --git a/drivers/pci/controller/cadence/pci-j721e.c b/drivers/pci/controller/cadence/pci-j721e.c
index e70213c9060a..b09924b010ab 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 +499,15 @@ 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);
+ gpiod_set_value_cansleep(perst_gpiod, 1);
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
