On Mon, Sep 14, 2020 at 11:29 AM Geert Uytterhoeven
<geert@xxxxxxxxxxxxxx> wrote:
> On Sat, Sep 12, 2020 at 11:19 PM <marek.vasut@xxxxxxxxx> wrote:
> > From: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
> >
> > The R-Car PCIe controller is capable of handling L0s/L1 link states.
> > While the controller can enter and exit L0s link state, and exit L1
> > link state, without any additional action from the driver, to enter
> > L1 link state, the driver must complete the link state transition by
> > issuing additional commands to the controller.
> >
> > The problem is, this transition is not atomic. The controller sets
> > PMEL1RX bit in PMSR register upon reception of PM_ENTER_L1 DLLP from
> > the PCIe card, but then the controller enters some sort of inbetween
> > state. The driver must detect this condition and complete the link
> > state transition, by setting L1IATN bit in PMCTLR and waiting for
> > the link state transition to complete.
> >
> > If a PCIe access happens inside of this window, where the controller
> > is inbetween L0 and L1 link states, the access generates a fault and
> > the ARM 'imprecise external abort' handler is invoked.
> >
> > Just like other PCI controller drivers, here we hook the fault handler,
> > perform the fixup to help the controller enter L1 link state, and then
> > restart the instruction which triggered the fault. Since the controller
> > is in L1 link state now, the link can exit from L1 link state to L0 and
> > successfully complete the access.
> >
> > Note that this fixup is applicable only to Aarch32 R-Car controllers,
> > the Aarch64 R-Car perform the same fixup in TFA, see TFA commit
> > 0969397f2 ("rcar_gen3: plat: Prevent PCIe hang during L1X config access")
> >
> > Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>
> > + */
> > + hook_fault_code(16 + 6, rcar_pcie_aarch32_abort_handler, SIGBUS, 0,
>
> After changing the "16 + 6" to "17", like pci-keystone.c does, it works!
Oh, this depends on LPAE. So it must be 17 if CONFIG_ARM_LPAE=y,
22 otherwise.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
