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

[Krishna Chaitanya Chundru]

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@xxxxxxxxxx>
>>
>> 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@xxxxxxxxxx>
>> Signed-off-by: Krishna Chaitanya Chundru <krishna.chundru@xxxxxxxxxxxxxxxx>
>> ---
> [...]
>
>> +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.
>> +		pci = pcie->pci;
>> +
>> +		if (pcie->global_irq)
>> +			disable_irq(pcie->global_irq);
> This changed the ordering of disabling things versus the previous
> revision, although I don't think it should matter given this
> IRQ currently only services the linkdown event
>
>
> Konrad