From 4d107d3b5a686b5834e533a00b73bf7b1cf59df7 Mon Sep 17 00:00:00 2001
From: Lucas Stach <l.stach@pengutronix.de>
Date: Mon, 25 Jan 2016 16:50:02 -0600
Subject: [PATCH] PCI: imx6: Move link up check into imx6_pcie_wait_for_link()
imx6_pcie_link_up() previously used usleep_range() to wait for the link to
come up. Since it may be called while holding the config spinlock, the
sleep causes a "BUG: scheduling while atomic" error.
Instead of waiting for the link to come up in imx6_pcie_link_up(), do the
waiting in imx6_pcie_wait_for_link(), where we're not holding a lock and
sleeping is allowed.
[bhelgaas: changelog, references to bugzilla and f95d3ae77191]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100031
Fixes: f95d3ae77191 ("PCI: imx6: Wait for retraining")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
drivers/pci/host/pci-imx6.c | 60 ++++++++++++++-----------------------
1 file changed, 22 insertions(+), 38 deletions(-)
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 6d7dfdcf4d5c5..bd3f7d0ef943d 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -349,10 +349,28 @@ static int imx6_pcie_wait_for_link(struct pcie_port *pp)
{
unsigned int retries;
+ /*
+ * Test if the PHY reports that the link is up and also that the LTSSM
+ * training finished. There are three possible states of the link when
+ * this code is called:
+ * 1) The link is DOWN (unlikely)
+ * The link didn't come up yet for some reason. This usually means
+ * we have a real problem somewhere, if it happens with a peripheral
+ * connected. This state calls for inspection of the DEBUG registers.
+ * 2) The link is UP, but still in LTSSM training
+ * Wait for the training to finish, which should take a very short
+ * time. If the training does not finish, we have a problem and we
+ * need to inspect the DEBUG registers. If the training does finish,
+ * the link is up and operating correctly.
+ * 3) The link is UP and no longer in LTSSM training
+ * The link is up and operating correctly.
+ */
for (retries = 0; retries < 200; retries++) {
- if (dw_pcie_link_up(pp))
+ u32 reg = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
+ if ((reg & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP) &&
+ !(reg & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
return 0;
- usleep_range(100, 1000);
+ usleep_range(1000, 2000);
}
return -EINVAL;
@@ -467,42 +485,8 @@ static void imx6_pcie_host_init(struct pcie_port *pp)
static int imx6_pcie_link_up(struct pcie_port *pp)
{
- u32 rc;
- int count = 5;
-
- /*
- * Test if the PHY reports that the link is up and also that the LTSSM
- * training finished. There are three possible states of the link when
- * this code is called:
- * 1) The link is DOWN (unlikely)
- * The link didn't come up yet for some reason. This usually means
- * we have a real problem somewhere. Reset the PHY and exit. This
- * state calls for inspection of the DEBUG registers.
- * 2) The link is UP, but still in LTSSM training
- * Wait for the training to finish, which should take a very short
- * time. If the training does not finish, we have a problem and we
- * need to inspect the DEBUG registers. If the training does finish,
- * the link is up and operating correctly.
- * 3) The link is UP and no longer in LTSSM training
- * The link is up and operating correctly.
- */
- while (1) {
- rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
- if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
- break;
- if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
- return 1;
- if (!count--)
- break;
- dev_dbg(pp->dev, "Link is up, but still in training\n");
- /*
- * Wait a little bit, then re-check if the link finished
- * the training.
- */
- usleep_range(1000, 2000);
- }
-
- return 0;
+ return readl(pp->dbi_base + PCIE_PHY_DEBUG_R1) &
+ PCIE_PHY_DEBUG_R1_XMLH_LINK_UP;
}
static struct pcie_host_ops imx6_pcie_host_ops = {
--
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