[PATCH] ARM: imx6: Fix "BUG: scheduling while atomic" if PCIe switch is attached
bhelgaas at google.com
Thu Jun 18 06:21:57 PDT 2015
On Thu, Jun 18, 2015 at 09:56:54AM +0200, David Müller wrote:
> This problem has already been reported as
> Signed-off-by: David Müller <dave.mueller at gmx.ch>
> drivers/pci/host/pci-imx6.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
> index fdb9536..c63691c 100644
> --- a/drivers/pci/host/pci-imx6.c
> +++ b/drivers/pci/host/pci-imx6.c
> @@ -489,7 +489,7 @@ static int imx6_pcie_link_up(struct pcie_port *pp)
> * Wait a little bit, then re-check if the link finished
> * the training.
> - usleep_range(1000, 2000);
> + mdelay(20);
> * From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
I asked in the bugzilla why imx6_pcie_link_up() looks nothing like the
other pcie_host_ops.link_up() methods.
> the i.MX6 link up routine is a bit more complex compared to the other
> designware drivers because of a hardware bug, where some FIFOs could
> get out of sync when changing the link speed. We need to start the
> link at Gen1, wait for it to be stable, then start a directed link
> speed change if the EP is Gen2 and wait for the link to be stable
> again. If the link doesn't come back, we need to start over.
> I don't think any of the other DW PCIe implementations need this
That explanation makes sense, and a comment to that effect should be
in the code. But I also wonder whether this workaround could be moved
to imx6_pcie_start_link() (just renamed to imx6_pcie_establish_link()).
Then imx6_pcie_link_up() could be a simple status check like the
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