On Fri, Jan 07, 2022 at 03:12:45AM +0000, Hongxing Zhu wrote:
> > -----Original Message-----
> > From: Fabio Estevam <festevam@xxxxxxxxx>
> > Sent: Thursday, January 6, 2022 6:37 PM
> > To: bhelgaas@xxxxxxxxxx
> > Cc: lorenzo.pieralisi@xxxxxxx; robh@xxxxxxxxxx;
> > l.stach@xxxxxxxxxxxxxx; Hongxing Zhu <hongxing.zhu@xxxxxxx>;
> > linux-pci@xxxxxxxxxxxxxxx; Fabio Estevam <festevam@xxxxxxxxx>;
> > stable@xxxxxxxxxxxxxxx
> > Subject: [PATCH v2] PCI: imx6: Allow to probe when
> > dw_pcie_wait_for_link() fails
> >
> > The intention of commit 886a9c134755 ("PCI: dwc: Move link handling
> > into common code") was to standardize the behavior of link down as
> > explained in its commit log:
> >
> > "The behavior for a link down was inconsistent as some drivers would fail
> > probe in that case while others succeed. Let's standardize this to succeed
> > as there are usecases where devices (and the link) appear later even
> > without hotplug. For example, a reconfigured FPGA device."
> >
> > The pci-imx6 still fails to probe when the link is not present, which causes
> > the following warning:
> >
> > imx6q-pcie 8ffc000.pcie: Phy link never came up
> > imx6q-pcie: probe of 8ffc000.pcie failed with error -110 ------------[ cut
> > here ]------------
> > WARNING: CPU: 0 PID: 30 at drivers/regulator/core.c:2257
> > _regulator_put.part.0+0x1b8/0x1dc Modules linked in:
> > CPU: 0 PID: 30 Comm: kworker/u2:2 Not tainted 5.15.0-next-20211103
> > #1 Hardware name: Freescale i.MX6 SoloX (Device Tree)
> > Workqueue: events_unbound async_run_entry_fn [<c0111730>]
> > (unwind_backtrace) from [<c010bb74>] (show_stack+0x10/0x14)
> > [<c010bb74>] (show_stack) from [<c0f90290>]
> > (dump_stack_lvl+0x58/0x70) [<c0f90290>] (dump_stack_lvl) from
> > [<c012631c>] (__warn+0xd4/0x154) [<c012631c>] (__warn) from
> > [<c0f87b00>] (warn_slowpath_fmt+0x74/0xa8) [<c0f87b00>]
> > (warn_slowpath_fmt) from [<c076b4bc>]
> > (_regulator_put.part.0+0x1b8/0x1dc)
> > [<c076b4bc>] (_regulator_put.part.0) from [<c076b574>]
> > (regulator_put+0x2c/0x3c) [<c076b574>] (regulator_put) from
> > [<c08c3740>] (release_nodes+0x50/0x178)
> >
> > Fix this problem by ignoring the dw_pcie_wait_for_link() error like it is
> > done on the other dwc drivers.
> >
> > Tested on imx6sx-sdb and imx6q-sabresd boards.
> >
> > Cc: <stable@xxxxxxxxxxxxxxx>
> > Fixes: 886a9c134755 ("PCI: dwc: Move link handling into common code")
> > Signed-off-by: Fabio Estevam <festevam@xxxxxxxxx>
> [Richard Zhu] Reviewed-by: Richard Zhu <hongxing.zhu@xxxxxxx>
Please, there is no need to add [Richard Zhu] to let us understand
it is you, this breaks tools that pick up tags automatically so
refrain from using it, thanks.
Lorenzo
> > Changes since v1:
> > - Remove the printk timestamp from the kernel warning log (Richard).
> >
> > drivers/pci/controller/dwc/pci-imx6.c | 10 ++--------
> > 1 file changed, 2 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 2ac081510632..5e8a03061b31 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -807,9 +807,7 @@ static int imx6_pcie_start_link(struct dw_pcie
> > *pci)
> > /* Start LTSSM. */
> > imx6_pcie_ltssm_enable(dev);
> >
> > - ret = dw_pcie_wait_for_link(pci);
> > - if (ret)
> > - goto err_reset_phy;
> > + dw_pcie_wait_for_link(pci);
> >
> > if (pci->link_gen == 2) {
> > /* Allow Gen2 mode after the link is up. */ @@ -845,11 +843,7
> > @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
> > }
> >
> > /* Make sure link training is finished as well! */
> > - ret = dw_pcie_wait_for_link(pci);
> > - if (ret) {
> > - dev_err(dev, "Failed to bring link up!\n");
> > - goto err_reset_phy;
> > - }
> > + dw_pcie_wait_for_link(pci);
> > } else {
> > dev_info(dev, "Link: Gen2 disabled\n");
> > }
> > --
> > 2.25.1
>
