Re: [PATCH v6 3/3] PCI: qcom: Implement shutdown() callback

[Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>]

On 9/9/2026 6:48 PM, Konrad Dybcio wrote:
> On 9/9/26 2:40 PM, Krishna Chaitanya Chundru wrote:
>>
>> On 9/9/2026 6:06 PM, Konrad Dybcio wrote:
>>> On 9/9/26 2:24 PM, Krishna Chaitanya Chundru wrote:
>>>> From: Manivannan Sadhasivam <mani@kernel.org>
>>>>
>>>> PCIe host controllers should bring the link down cleanly before system
>>>> shutdown/reboot proceeds to remove power/clocks from the controller.
>>>> Without this, the link may still be up and endpoints still have
>>>> transactions in flight when power/clocks are cut, which can trip SMMU
>>>> translation faults or NoC protocol errors.
>>>>
>>>> Reuse dw_pcie_suspend_noirq() in the shutdown path to force the link
>>>> into L2, putting it into D3cold.
>>>>
>>>> device_shutdown() runs with interrupts enabled, unlike suspend_noirq().
>>>> Mask the chained MSI IRQ(s) and the Global IRQ before tearing down the
>>>> link and clocks/PHY, since a late/spurious interrupt could otherwise
>>>> reach a handler that touches now-unclocked PARF/DBI registers.
>>>>
>>>> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>>>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@oss.qualcomm.com>
>>>> ---
>>> [...]
>>>
>>>> +static void qcom_pcie_shutdown(struct platform_device *pdev)
>>>> +{
>>>> +	const struct qcom_pcie_cfg *pcie_cfg = of_device_get_match_data(&pdev->dev);
>>>> +	struct qcom_pcie *pcie;
>>>> +	struct dw_pcie *pci;
>>>> +
>>>> +	if (pcie_cfg && pcie_cfg->firmware_managed) {
>>>> +		/*
>>>> +		 * Firmware owns the link teardown and clock/PHY shutdown in
>>>> +		 * this mode; Linux only owns the chained MSI IRQ(s), which
>>>> +		 * still need to be masked off before shutdown proceeds.
>>>> +		 */
>>>> +		pci = platform_get_drvdata(pdev);
>>>> +	} else {
>>>> +		pcie = platform_get_drvdata(pdev);
>>> This is no less than an intriguing choice.. please store the same
>>> element in both cases so we don't have to do this
>> for firmware_managed solutions struct qcom_pcie *pcie is not being
>> used/allocated at all. it will waste of memory if we allocate memory for just
>> this use case. - Krishna Chaitanya.
> Should we move it to a separate file/driver then, perhaps?
> We could share the ECAM ops in e.g. pcie-qcom-common.c
I will let Mani to comment on this.

- Krishna Chaitanya.
>
> Konrad