On 9/8/26 07:17, Siddharth Vadapalli wrote:
The 'reset-gpios' property specified in the device-tree corresponds to
the PCI PERST# signal that is used to reset a PCI Endpoint. Since the
on-board circuitry may not reset the PCI Endpoint, fetch the 'reset-gpios'
device-tree property and toggle the GPIO line corresponding to the PERST#
signal to enable the PCI Endpoint. In the absence of the 'reset-gpios'
property in the device-tree, existing behavior is retained rather than
returning an error.
Signed-off-by: Siddharth Vadapalli <[email protected]>
---
Polarity of the Reset GPIO pins has been fixed since the v1 patch.
drivers/pci/pcie_dw_ti.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)
diff --git a/drivers/pci/pcie_dw_ti.c b/drivers/pci/pcie_dw_ti.c
index fb39132f7c1..ac2045991c2 100644
--- a/drivers/pci/pcie_dw_ti.c
+++ b/drivers/pci/pcie_dw_ti.c
@@ -58,6 +58,7 @@ struct pcie_dw_ti {
/* Must be first member of the struct */
struct pcie_dw dw;
void *app_base;
+ struct gpio_desc rst_gpio;
u32 num_lanes;
};
@@ -252,6 +253,17 @@ static int pcie_dw_ti_probe(struct udevice *dev)
return ret;
}
+ ret = gpio_request_by_name(dev, "reset-gpios", 0, &pci->rst_gpio,
+ GPIOD_IS_OUT);
+ if (ret && ret != -ENOENT) {
+ dev_err(dev, "failed to get reset-gpios\n");
+ return ret;
+ }
+
+ /* Keep the reset-line asserted until the PCI Controller is ready */
+ if (dm_gpio_is_valid(&pci->rst_gpio))
+ dm_gpio_set_value(&pci->rst_gpio, 0);
+
ret = generic_phy_get_by_name(dev, "pcie-phy0", &phy0);
if (ret) {
dev_err(dev, "Unable to get phy0");
@@ -281,6 +293,15 @@ static int pcie_dw_ti_probe(struct udevice *dev)
dw_pcie_link_set_max_link_width(&pci->dw, pci->num_lanes);
+ /*
+ * The reset-gpio (PERST#) should be held deasserted for at-least 100 ms
+ * before the link is brought up.
+ */
+ if (dm_gpio_is_valid(&pci->rst_gpio)) {
+ dm_gpio_set_value(&pci->rst_gpio, 1);
+ mdelay(100);
+ }
+
if (!pcie_dw_ti_pcie_link_up(pci, LINK_SPEED_GEN_2)) {
printf("PCIE-%d: Link down\n", dev_seq(dev));
return -ENODEV;
Reviewed-by: Neil Armstrong <[email protected]>
Thanks,
Neil
