On Mon, May 22, 2017 at 05:13:46PM -0500, Bjorn Helgaas wrote:
> On Wed, May 10, 2017 at 07:57:52PM +0200, Lucas Stach wrote:
> > The change in Linux 4.12 to make PCI configuartion requests non-posted
> > means that we are now getting a synchronous abort when the CFG space
> > read to probe for downstream devices times out.
> >
> > Synchronous aborts need to be handled differently from the async aborts
> > we were getting before, in particular the PC needs to be advanced when
> > resolving the abort. This is mostly a copy of what other PCI drivers do
> > on ARM to handle those aborts.
> >
> > Signed-off-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
>
> Applied to for-linus for v4.12 with tested-by and acks from Fabio,
> Peter, and Richard. I updated the subject line to:
>
> PCI: imx6: Fix config read timeout handling
>
> because I don't think this change is specific to bus scanning and I
> wanted a hint that it's related to the config space mapping changes.
>
> In fact, I'd really like to include the specific commit that caused
> this problem so that if the original commit is backported, there's a
> hint that we should backport this one, too. I *think* it might be
> cc7b0d495589, so I updated the changelog to this:
>
> Commit cc7b0d495589 ("PCI: designware: Update PCI config space remap
> function") made PCI configuration requests non-posted, which means we now
> get a synchronous abort when the CFG space read to probe for downstream
> devices times out.
>
> Synchronous aborts need to be handled differently from the async aborts we
> were getting before, in particular the PC needs to be advanced when
> resolving the abort. This is mostly a copy of what other PCI drivers do on
> ARM to handle those aborts.
>
> [bhelgaas: changelog, "Fixes"]
> Fixes: cc7b0d495589 ("PCI: designware: Update PCI config space remap function")
>
> Please let me know if this is the wrong commit.
I think it is the right commit but it is better if Lucas can confirm,
apologies for the breakage caused, I just could not test on iMX6.
Thanks,
Lorenzo
> > This is a fix that needs to go in for 4.12, but I would hope to get
> > some thorough testing before.
> > ---
> > drivers/pci/dwc/pci-imx6.c | 33 ++++++++++++++++++++++++++++++---
> > 1 file changed, 30 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/dwc/pci-imx6.c b/drivers/pci/dwc/pci-imx6.c
> > index a98cba55c7f0..19a289b8cc94 100644
> > --- a/drivers/pci/dwc/pci-imx6.c
> > +++ b/drivers/pci/dwc/pci-imx6.c
> > @@ -252,7 +252,34 @@ static void imx6_pcie_reset_phy(struct imx6_pcie *imx6_pcie)
> > static int imx6q_pcie_abort_handler(unsigned long addr,
> > unsigned int fsr, struct pt_regs *regs)
> > {
> > - return 0;
> > + unsigned long pc = instruction_pointer(regs);
> > + unsigned long instr = *(unsigned long *)pc;
> > + int reg = (instr >> 12) & 15;
> > +
> > + /*
> > + * If the instruction being executed was a read,
> > + * make it look like it read all-ones.
> > + */
> > + if ((instr & 0x0c100000) == 0x04100000) {
> > + unsigned long val;
> > +
> > + if (instr & 0x00400000)
> > + val = 255;
> > + else
> > + val = -1;
> > +
> > + regs->uregs[reg] = val;
> > + regs->ARM_pc += 4;
> > + return 0;
> > + }
> > +
> > + if ((instr & 0x0e100090) == 0x00100090) {
> > + regs->uregs[reg] = -1;
> > + regs->ARM_pc += 4;
> > + return 0;
> > + }
> > +
> > + return 1;
> > }
> >
> > static void imx6_pcie_assert_core_reset(struct imx6_pcie *imx6_pcie)
> > @@ -819,8 +846,8 @@ static int __init imx6_pcie_init(void)
> > * we can install the handler here without risking it
> > * accessing some uninitialized driver state.
> > */
> > - hook_fault_code(16 + 6, imx6q_pcie_abort_handler, SIGBUS, 0,
> > - "imprecise external abort");
> > + hook_fault_code(8, imx6q_pcie_abort_handler, SIGBUS, 0,
> > + "external abort on non-linefetch");
> >
> > return platform_driver_register(&imx6_pcie_driver);
> > }
> > --
> > 2.11.0
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
