diff options
| author | Wilfred Mallawa <wilfred.mallawa@wdc.com> | 2025-06-13 12:19:09 +0200 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2025-06-19 10:57:31 -0500 |
| commit | c0b93754547dde16c8370b8fdad5f396e7786647 (patch) | |
| tree | c7e056a8aa67bcd08c8101555453b17eaeb1846a /drivers/pci/controller/dwc | |
| parent | 19272b37aa4f83ca52bdf9c16d5d81bdd1354494 (diff) | |
PCI: dw-rockchip: Delay link training after hot reset in EP mode
RK3588 TRM, section "11.6.1.3.3 Hot Reset and Link-Down Reset" states that:
If you want to delay link re-establishment (after reset) so that you can
reprogram some registers through DBI, you must set app_ltssm_enable =0
immediately after core_rst_n as shown in above. This can be achieved by
enable the app_dly2_en, and end-up the delay by assert app_dly2_done.
I.e. setting app_dly2_en will automatically deassert app_ltssm_enable on
a hot reset, and setting app_dly2_done will re-assert app_ltssm_enable,
re-enabling link training.
When receiving a hot reset/link-down IRQ when running in EP mode, we will
call dw_pcie_ep_linkdown(), which may update registers through DBI. Unless
link training is inhibited, these register updates race with the link
training.
To avoid the race, set PCIE_LTSSM_APP_DLY2_EN so the controller never
automatically trains the link after a link-down or hot reset interrupt.
That way any DBI updates done in the dw_pcie_ep_linkdown() path will happen
while the link is still down. Then allow link training by setting
PCIE_LTSSM_APP_DLY2_DONE
Co-developed-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Wilfred Mallawa <wilfred.mallawa@wdc.com>
Signed-off-by: Niklas Cassel <cassel@kernel.org>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Link: https://patch.msgid.link/20250613101908.2182053-2-cassel@kernel.org
Diffstat (limited to 'drivers/pci/controller/dwc')
| -rw-r--r-- | drivers/pci/controller/dwc/pcie-dw-rockchip.c | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c index 93171a392879..cd1e9352b21f 100644 --- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c +++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c @@ -58,6 +58,8 @@ /* Hot Reset Control Register */ #define PCIE_CLIENT_HOT_RESET_CTRL 0x180 +#define PCIE_LTSSM_APP_DLY2_EN BIT(1) +#define PCIE_LTSSM_APP_DLY2_DONE BIT(3) #define PCIE_LTSSM_ENABLE_ENHANCE BIT(4) /* LTSSM Status Register */ @@ -474,7 +476,7 @@ static irqreturn_t rockchip_pcie_ep_sys_irq_thread(int irq, void *arg) struct rockchip_pcie *rockchip = arg; struct dw_pcie *pci = &rockchip->pci; struct device *dev = pci->dev; - u32 reg; + u32 reg, val; reg = rockchip_pcie_readl_apb(rockchip, PCIE_CLIENT_INTR_STATUS_MISC); rockchip_pcie_writel_apb(rockchip, reg, PCIE_CLIENT_INTR_STATUS_MISC); @@ -485,6 +487,10 @@ static irqreturn_t rockchip_pcie_ep_sys_irq_thread(int irq, void *arg) if (reg & PCIE_LINK_REQ_RST_NOT_INT) { dev_dbg(dev, "hot reset or link-down reset\n"); dw_pcie_ep_linkdown(&pci->ep); + /* Stop delaying link training. */ + val = HIWORD_UPDATE_BIT(PCIE_LTSSM_APP_DLY2_DONE); + rockchip_pcie_writel_apb(rockchip, val, + PCIE_CLIENT_HOT_RESET_CTRL); } if (reg & PCIE_RDLH_LINK_UP_CHGED) { @@ -566,8 +572,11 @@ static int rockchip_pcie_configure_ep(struct platform_device *pdev, return ret; } - /* LTSSM enable control mode */ - val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE); + /* + * LTSSM enable control mode, and automatically delay link training on + * hot reset/link-down reset. + */ + val = HIWORD_UPDATE_BIT(PCIE_LTSSM_ENABLE_ENHANCE | PCIE_LTSSM_APP_DLY2_EN); rockchip_pcie_writel_apb(rockchip, val, PCIE_CLIENT_HOT_RESET_CTRL); rockchip_pcie_writel_apb(rockchip, PCIE_CLIENT_EP_MODE, |