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>

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 6d7dfdcf4d5c5620b4e67a1dc4259fc13b32f20d..bd3f7d0ef943d6af6c57ba60c592908fa8caddb9 100644 (file)
--- 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 = {