[PATCH u-boot-marvell 1/3] arm: a37xx: pci: Do not try to access other buses when link is down

Pali Rohár
2022-02-15T10:24:12Z

If a PIO request is executed while link-down, the whole controller gets
stuck in a non-functional state, and even after link comes up again, PIO
requests won't work anymore, and a reset of the whole PCIe controller is
needed. Therefore we need to prevent sending PIO requests while the link
is down.

Signed-off-by: Pali Rohár <pali@kernel.org>
---
drivers/pci/pci-aardvark.c | 38 +++++++++++++++++++++-----------------
1 file changed, 21 insertions(+), 17 deletions(-)

diff --git a/drivers/pci/pci-aardvark.c b/drivers/pci/pci-aardvark.c
index 1eb257ea8b4a..ccaeecaca8e3 100644
--- a/drivers/pci/pci-aardvark.c
+++ b/drivers/pci/pci-aardvark.c
@@ -177,6 +177,23 @@ static inline uint advk_readl(struct pcie_advk *pcie, uint reg)
return readl(pcie->base + reg);
}

+/**
+ * pcie_advk_link_up() - Check if PCIe link is up or not
+ *
+ * @pcie: The PCI device to access
+ *
+ * Return true on link up.
+ * Return false on link down.
+ */
+static bool pcie_advk_link_up(struct pcie_advk *pcie)
+{
+ u32 val, ltssm_state;
+
+ val = advk_readl(pcie, ADVK_LMI_PHY_CFG0);
+ ltssm_state = (val & ADVK_LMI_PHY_CFG0_LTSSM_MASK) >> ADVK_LMI_PHY_CFG0_LTSSM_SHIFT;
+ return ltssm_state >= ADVK_LMI_PHY_CFG0_LTSSM_L0 && ltssm_state < ADVK_LMI_PHY_CFG0_LTSSM_DISABLED;
+}
+
/**
* pcie_advk_addr_valid() - Check for valid bus address
*
@@ -195,6 +212,10 @@ static bool pcie_advk_addr_valid(struct pcie_advk *pcie,
if (busno == 0 && (dev != 0 || func != 0))
return false;

+ /* Access to other buses is possible when link is up */
+ if (busno != 0 && !pcie_advk_link_up(pcie))
+ return false;
+
/*
* In PCI-E only a single device (0) can exist on the secondary bus.
* Beyond the secondary bus, there might be a Switch and anything is
@@ -618,23 +639,6 @@ retry:
return ret;
}

-/**
- * pcie_advk_link_up() - Check if PCIe link is up or not
- *
- * @pcie: The PCI device to access
- *
- * Return 1 (true) on link up.
- * Return 0 (false) on link down.
- */
-static int pcie_advk_link_up(struct pcie_advk *pcie)
-{
- u32 val, ltssm_state;
-
- val = advk_readl(pcie, ADVK_LMI_PHY_CFG0);
- ltssm_state = (val & ADVK_LMI_PHY_CFG0_LTSSM_MASK) >> ADVK_LMI_PHY_CFG0_LTSSM_SHIFT;
- return ltssm_state >= ADVK_LMI_PHY_CFG0_LTSSM_L0 && ltssm_state < ADVK_LMI_PHY_CFG0_LTSSM_DISABLED;
-}
-
/**
* pcie_advk_wait_for_link() - Wait for link training to be accomplished
*
--
2.20.1