Re: [PATCH v11 04/11] PCI: brcmstb: Add suspend and resume pm_ops

Florian Fainelli
2020-09-10T19:10:00Z

On 9/10/2020 12:05 PM, Jim Quinlan wrote:
> On Thu, Sep 10, 2020 at 2:50 PM Rob Herring <robh@kernel.org> wrote:
>>
>> On Thu, Sep 10, 2020 at 10:42 AM Jim Quinlan <james.quinlan@broadcom.com> wrote:
>>>
>>> On Thu, Sep 10, 2020 at 11:56 AM Rob Herring <robh@kernel.org> wrote:
>>>>
>>>> On Mon, Aug 24, 2020 at 03:30:17PM -0400, Jim Quinlan wrote:
>>>>> From: Jim Quinlan <jquinlan@broadcom.com>
>>>>>
>>>>> Broadcom Set-top (BrcmSTB) boards typically support S2, S3, and S5 suspend
>>>>> and resume. Now the PCIe driver may do so as well.
>>>>>
>>>>> Signed-off-by: Jim Quinlan <jquinlan@broadcom.com>
>>>>> Acked-by: Florian Fainelli <f.fainelli@gmail.com>
>>>>> ---
>>>>> drivers/pci/controller/pcie-brcmstb.c | 47 +++++++++++++++++++++++++++
>>>>> 1 file changed, 47 insertions(+)
>>>>>
>>>>> diff --git a/drivers/pci/controller/pcie-brcmstb.c b/drivers/pci/controller/pcie-brcmstb.c
>>>>> index c2b3d2946a36..3d588ab7a6dd 100644
>>>>> --- a/drivers/pci/controller/pcie-brcmstb.c
>>>>> +++ b/drivers/pci/controller/pcie-brcmstb.c
>>>>> @@ -978,6 +978,47 @@ static void brcm_pcie_turn_off(struct brcm_pcie *pcie)
>>>>> brcm_pcie_bridge_sw_init_set(pcie, 1);
>>>>> }
>>>>>
>>>>> +static int brcm_pcie_suspend(struct device *dev)
>>>>> +{
>>>>> + struct brcm_pcie *pcie = dev_get_drvdata(dev);
>>>>> +
>>>>> + brcm_pcie_turn_off(pcie);
>>>>> + clk_disable_unprepare(pcie->clk);
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> +static int brcm_pcie_resume(struct device *dev)
>>>>> +{
>>>>> + struct brcm_pcie *pcie = dev_get_drvdata(dev);
>>>>> + void __iomem *base;
>>>>> + u32 tmp;
>>>>> + int ret;
>>>>> +
>>>>> + base = pcie->base;
>>>>> + clk_prepare_enable(pcie->clk);
>>>>> +
>>>>> + /* Take bridge out of reset so we can access the SERDES reg */
>>>>> + brcm_pcie_bridge_sw_init_set(pcie, 0);
>>>>> +
>>>>> + /* SERDES_IDDQ = 0 */
>>>>> + tmp = readl(base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
>>>>> + u32p_replace_bits(&tmp, 0, PCIE_MISC_HARD_PCIE_HARD_DEBUG_SERDES_IDDQ_MASK);
>>>>> + writel(tmp, base + PCIE_MISC_HARD_PCIE_HARD_DEBUG);
>>>>> +
>>>>> + /* wait for serdes to be stable */
>>>>> + udelay(100);
>>>>
>>>> Really needs to be a spinloop?
>>>>
>>>>> +
>>>>> + ret = brcm_pcie_setup(pcie);
>>>>> + if (ret)
>>>>> + return ret;
>>>>> +
>>>>> + if (pcie->msi)
>>>>> + brcm_msi_set_regs(pcie->msi);
>>>>> +
>>>>> + return 0;
>>>>> +}
>>>>> +
>>>>> static void __brcm_pcie_remove(struct brcm_pcie *pcie)
>>>>> {
>>>>> brcm_msi_remove(pcie);
>>>>> @@ -1087,12 +1128,18 @@ static int brcm_pcie_probe(struct platform_device *pdev)
>>>>>
>>>>> MODULE_DEVICE_TABLE(of, brcm_pcie_match);
>>>>>
>>>>> +static const struct dev_pm_ops brcm_pcie_pm_ops = {
>>>>> + .suspend_noirq = brcm_pcie_suspend,
>>>>> + .resume_noirq = brcm_pcie_resume,
>>>>
>>>> Why do you need interrupts disabled? There's 39 cases of .suspend_noirq
>>>> and 1352 of .suspend in the tree.
>>>
>>> I will test switching this to suspend_late/resume_early.
>>
>> Why not just the 'regular' flavor suspend/resume?
>>
>> Rob
> We must have our PCIe driver suspend last and resume first because our
> current driver turns off/on the power for the EPs. Note that this
> code isn't in the driver as we are still figuring out a way to make it
> upstreamable.

The suspend/resume ordering should be guaranteed by the Linux device
driver model though if not, this is a bug that ought to be fixed. The
PCI bridge sits at the top of the pci_device list and all EPs should be
child devices, so the suspend order should be from EPs down to the
bridge, and the resume the converse.
--
Florian