From afc9595ea4770f0157ae06fb3acedff703e169b6 Mon Sep 17 00:00:00 2001 From: Shawn Lin Date: Thu, 12 Jan 2017 09:53:17 +0800 Subject: [PATCH] PCI: rockchip: Disable RC's ASPM L0s based on DT "aspm-no-l0s" Rockchip's RC produces a 100MHz reference clock but there are two methods for the PHY to generate it: (1) Use the system PLL to generate a 100MHz clock. The PHY will relock it, filter signal noise, and output the reference clock. ASPM L0s works correctly, but circuit noise issues make it difficult to pass the TX compatibility test. (2) Share the SoC's 24MHZ crystal oscillator with the PHY and force the PHY's PLL to generate 100MHz internally. In this case, exit from ASPM L0s sometimes fails due to a design error in the RC receiver circuit. Even if we use extended-synch, the PHY sometimes fails to relock the bits from FTS, which will hang the system. We want the flexibility to use both clocking methods, so add a DT property, "aspm-no-l0s". If that's present, disable L0s to avoid the issues with case (2). [bhelgaas: changelog] Reported-by: Jeffy Chen Signed-off-by: Shawn Lin Signed-off-by: Bjorn Helgaas Reviewed-by: Brian Norris Acked-by: Rob Herring --- Documentation/devicetree/bindings/pci/rockchip-pcie.txt | 2 ++ drivers/pci/host/pcie-rockchip.c | 9 +++++++++ 2 files changed, 11 insertions(+) diff --git a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt index 71aeda1ca055..1453a734c2f5 100644 --- a/Documentation/devicetree/bindings/pci/rockchip-pcie.txt +++ b/Documentation/devicetree/bindings/pci/rockchip-pcie.txt @@ -43,6 +43,8 @@ Required properties: - interrupt-map-mask and interrupt-map: standard PCI properties Optional Property: +- aspm-no-l0s: RC won't support ASPM L0s. This property is needed if + using 24MHz OSC for RC's PHY. - ep-gpios: contain the entry for pre-reset gpio - num-lanes: number of lanes to use - vpcie3v3-supply: The phandle to the 3.3v regulator to use for PCIe. diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c index 03923494825d..0d6e8ee5b017 100644 --- a/drivers/pci/host/pcie-rockchip.c +++ b/drivers/pci/host/pcie-rockchip.c @@ -145,6 +145,8 @@ #define PCIE_RC_CONFIG_DCR_CSPL_SHIFT 18 #define PCIE_RC_CONFIG_DCR_CSPL_LIMIT 0xff #define PCIE_RC_CONFIG_DCR_CPLS_SHIFT 26 +#define PCIE_RC_CONFIG_LINK_CAP (PCIE_RC_CONFIG_BASE + 0xcc) +#define PCIE_RC_CONFIG_LINK_CAP_L0S BIT(10) #define PCIE_RC_CONFIG_LCS (PCIE_RC_CONFIG_BASE + 0xd0) #define PCIE_RC_CONFIG_L1_SUBSTATE_CTRL2 (PCIE_RC_CONFIG_BASE + 0x90c) #define PCIE_RC_CONFIG_THP_CAP (PCIE_RC_CONFIG_BASE + 0x274) @@ -665,6 +667,13 @@ static int rockchip_pcie_init_port(struct rockchip_pcie *rockchip) status &= ~PCIE_RC_CONFIG_THP_CAP_NEXT_MASK; rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_THP_CAP); + /* Clear L0s from RC's link cap */ + if (of_property_read_bool(dev->of_node, "aspm-no-l0s")) { + status = rockchip_pcie_read(rockchip, PCIE_RC_CONFIG_LINK_CAP); + status &= ~PCIE_RC_CONFIG_LINK_CAP_L0S; + rockchip_pcie_write(rockchip, status, PCIE_RC_CONFIG_LINK_CAP); + } + rockchip_pcie_write(rockchip, 0x0, PCIE_RC_BAR_CONF); rockchip_pcie_write(rockchip, -- 2.39.2