On Sat, Feb 19, 2022 at 4:46 AM <marek.vasut@xxxxxxxxx> wrote:
> From: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
>
> In case the controller is transitioning to L1 in rcar_pcie_config_access(),
> any read/write access to PCIECDR triggers asynchronous external abort. This
> is because the transition to L1 link state must be manually finished by the
> driver. The PCIe IP can transition back from L1 state to L0 on its own.
>
> The current asynchronous external abort hook implementation restarts
> the instruction which finally triggered the fault, which can be a
> different instruction than the read/write instruction which started
> the faulting access. Usually the instruction which finally triggers
> the fault is one which has some data dependency on the result of the
> read/write. In case of read, the read value after fixup is undefined,
> while a read value of faulting read should be PCI_ERROR_RESPONSE.
>
> It is possible to enforce the fault using 'isb' instruction placed
> right after the read/write instruction which started the faulting
> access. Add custom register accessors which perform the read/write
> followed immediately by 'isb'.
>
> This way, the fault always happens on the 'isb' and in case of read,
> which is located one instruction before the 'isb', it is now possible
> to fix up the return value of the read in the asynchronous external
> abort hook and make that read return PCI_ERROR_RESPONSE.
>
> Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
With this series applied, my koelsch (R-Car M2-W) with Intel 9301CT
Gigabit Ethernet adapter survived 1000 suspend/resume cycles.
Before, it would lock-up after a handful tries.
Tested-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
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
