shinys000114/linux
1
0
Fork 0
mirror of https://github.com/hardkernel/linux.git synced 2026-06-09 12:17:12 +09:00
Code Issues Packages Projects Releases Wiki Activity

PCI: rockchip: dw: Move deassert #PERST after enabling LTSSM

Browse Source 
It was recommended by ECN document, so following it will make
less risk in probing devices in case the refclk is coming from
SoC.

Change-Id: Ic4514f373b6014c406d5436738419c64df6d32b2
Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
This commit is contained in:
Shawn Lin
2021-03-16 17:45:10 +08:00
committed by Tao Huang
parent 9a75da1582
commit c84a4aa411
1 changed files with 12 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
drivers/pci/controller/dwc/pcie-dw-rockchip.c
View File

@@ -445,8 +445,6 @@ static int rk_pcie_establish_link(struct dw_pcie *pci)
/* Rest the device */ /* Rest the device */
gpiod_set_value_cansleep(rk_pcie->rst_gpio, 0); gpiod_set_value_cansleep(rk_pcie->rst_gpio, 0);
msleep(1000);
gpiod_set_value_cansleep(rk_pcie->rst_gpio, 1);
rk_pcie_disable_ltssm(rk_pcie); rk_pcie_disable_ltssm(rk_pcie);
rk_pcie_link_status_clear(rk_pcie); rk_pcie_link_status_clear(rk_pcie);
@@ -455,6 +453,18 @@ static int rk_pcie_establish_link(struct dw_pcie *pci)
/* Enable LTSSM */ /* Enable LTSSM */
rk_pcie_enable_ltssm(rk_pcie); rk_pcie_enable_ltssm(rk_pcie);
/*
* PCIe requires the refclk to be stable for 100µs prior to releasing
* PERST. See table 2-4 in section 2.6.2 AC Specifications of the PCI
* Express Card Electromechanical Specification, 1.1. However, we don't
* know if the refclk is coming from RC's PHY or external OSC. If it's
* from RC, so enabling LTSSM is the just right place to release #PERST.
* We need a little more extra time as before, rather than setting just
* 100us as we don't know how long should the device need to reset.
*/
msleep(1000);
gpiod_set_value_cansleep(rk_pcie->rst_gpio, 1);
for (retries = 0; retries < 10; retries++) { for (retries = 0; retries < 10; retries++) {
if (dw_pcie_link_up(pci)) { if (dw_pcie_link_up(pci)) {
dev_info(pci->dev, "PCIe Link up, LTSSM is 0x%x\n", dev_info(pci->dev, "PCIe Link up, LTSSM is 0x%x\n",