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PCI: imx6: Move link up check into imx6_pcie_wait_for_link()

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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 f95d3ae771]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=100031
Fixes: f95d3ae771 ("PCI: imx6: Wait for retraining")
Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
This commit is contained in:
Lucas Stach 2016-01-25 16:50:02 -06:00 committed by Bjorn Helgaas
parent a77c5422d7
commit 4d107d3b5a
1 changed files with 22 additions and 38 deletions
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60
drivers/pci/host/pci-imx6.c
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@ -349,10 +349,28 @@ static int imx6_pcie_wait_for_link(struct pcie_port *pp)
{ {
unsigned int retries; 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++) { 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; return 0;
usleep_range(100, 1000); usleep_range(1000, 2000);
} }
return -EINVAL; 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) static int imx6_pcie_link_up(struct pcie_port *pp)
{ {
u32 rc; return readl(pp->dbi_base + PCIE_PHY_DEBUG_R1) &
int count = 5; PCIE_PHY_DEBUG_R1_XMLH_LINK_UP;
/*
* 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;
} }
static struct pcie_host_ops imx6_pcie_host_ops = { static struct pcie_host_ops imx6_pcie_host_ops = {