On Fri, Jul 28, 2023 at 12:15 PM Jim Quinlan <james.quinlan@xxxxxxxxxxxx> wrote:
>
>
>
> On Thu, Jul 27, 2023, 10:44 PM Lorenzo Pieralisi <lpieralisi@xxxxxxxxxx> wrote:
>>
>> On Fri, Jun 23, 2023 at 10:40:56AM -0400, Jim Quinlan wrote:
>> > During long periods of the PCIe RC HW being in an L1SS sleep state, there
>> > may be a timeout on an internal bus access, even though there may not be
>> > any PCIe access involved. Such a timeout will cause a subsequent CPU
>> > abort.
>> >
>> > So, when "brcm,enable-l1ss" is observed, we increase the timeout value to
>> > four seconds instead of using its HW default.
>> >
>> > Signed-off-by: Jim Quinlan <james.quinlan@xxxxxxxxxxxx>
>> > Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
>> > ---
>> > drivers/pci/controller/pcie-brcmstb.c | 16 ++++++++++++++++
>> > 1 file changed, 16 insertions(+)
>> >
>> > diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
>> > index d30636a725d7..fe0415a98c63 100644
>> > --- a/drivers/pci/controller/pcie-brcmstb.c
>> > +++ b/drivers/pci/controller/pcie-brcmstb.c
>> > @@ -1034,6 +1034,21 @@ static int brcm_pcie_setup(struct brcm_pcie *pcie)
>> > return 0;
>> > }
>> >
>> > +/*
>> > + * This extends the timeout period for an access to an internal bus. This
>> > + * access timeout may occur during L1SS sleep periods even without the
>> > + * presence of a PCIe access.
>> > + */
>> > +static void brcm_extend_rbus_timeout(struct brcm_pcie *pcie)
>> > +{
>> > + /* TIMEOUT register is two registers before RGR1_SW_INIT_1 */
>> > + const unsigned int REG_OFFSET = PCIE_RGR1_SW_INIT_1(pcie) - 8;
>>
>> Nit: you could define an offset for the TIMEOUT register, if that makes
>> it any cleaner, up to you.
>>
>> > + u32 timeout_us = 4000000; /* 4 seconds, our setting for L1SS */
>>
>> It would be useful to describe why this has to be 4 seconds in case
>> someone in the future will have to change it.
>
>
> Hello,
> IIRC our customer requested 2s and we doubled it. Bjorn, can you please add this comment or a paraphrase of it before applying -- I'm currently on vacation.
Hello Bjorn,
Is the above request okay with you? What is the status of these
commits -- will they be applied to pci-next in the near future?
Regards,
Jim Quinlan
Broadcom STB
>
> Regards,
> Jim Quinlan
>
>>
>> Thanks,
>> Lorenzo
>>
>> > + /* Each unit in timeout register is 1/216,000,000 seconds */
>> > + writel(216 * timeout_us, pcie->base + REG_OFFSET);
>> > +}
>> > +
>> > static void brcm_config_clkreq(struct brcm_pcie *pcie)
>> > {
>> > bool l1ss = of_property_read_bool(pcie->np, "brcm,enable-l1ss");
>> > @@ -1059,6 +1074,7 @@ static void brcm_config_clkreq(struct brcm_pcie *pcie)
>> > * of 400ns, as specified in 3.2.5.2.2 of the PCI Express
>> > * Mini CEM 2.0 specification.
>> > */
>> > + brcm_extend_rbus_timeout(pcie);
>> > clkreq_set |= PCIE_MISC_HARD_PCIE_HARD_DEBUG_L1SS_ENABLE_MASK;
>> > dev_info(pcie->dev, "bi-dir CLKREQ# for L1SS power savings");
>> > } else {
>> > --
>> > 2.17.1
>> >
>>
>>
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