[PATCH v3 2/2] PCI: rockchip-host: Wait 100ms after reset before starting configuration

Damien Le Moal
2024-04-12T02:37:40Z

The PCI Express Base Specification r6.0, section 6.6.1, states that the
host should wait for at least 100 msec from the end of a conventional
reset (PERST# is de-asserted) before sending a configuration request to
ensure that the device is able to respond with a "Request Retry Status"
completion.

Add the PCIE_T_RRS_READY_MS macro to define this wait time and modify
rockchip_pcie_host_init_port() to add this 100ms sleep after bringing
back PESRT# signal to high using the ep_gpio GPIO.

Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
drivers/pci/controller/pcie-rockchip-host.c | 2 ++
drivers/pci/pci.h | 7 +++++++
2 files changed, 9 insertions(+)

diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c
index fc868251e570..cbec71114825 100644
--- a/drivers/pci/controller/pcie-rockchip-host.c
+++ b/drivers/pci/controller/pcie-rockchip-host.c
@@ -325,6 +325,8 @@ static int rockchip_pcie_host_init_port(struct rockchip_pcie *rockchip)
msleep(PCIE_T_PVPERL_MS);
gpiod_set_value_cansleep(rockchip->ep_gpio, 1);

+ msleep(PCIE_T_RRS_READY_MS);
+
/* 500ms timeout value should be enough for Gen1/2 training */
err = readl_poll_timeout(rockchip->apb_base + PCIE_CLIENT_BASIC_STATUS1,
status, PCIE_LINK_UP(status), 20,
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index 17fed1846847..c93ffc5e6e1f 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -16,6 +16,13 @@
/* Power stable to PERST# inactive from PCIe card Electromechanical Spec */
#define PCIE_T_PVPERL_MS 100

+/*
+ * End of conventional reset (PERST# de-asserted) to first configuration
+ * request (device able to respond with a "Request Retry Status" completion),
+ * from PCI Express Base Specification r6.0, section 6.6.1.
+ */
+#define PCIE_T_RRS_READY_MS 100
+
/*
* PCIe r6.0, sec 5.3.3.2.1 <PME Synchronization>
* Recommends 1ms to 10ms timeout to check L2 ready.
--
2.44.0