Re: [PATCH v3 5/5] PCI: qcom: Add support for resetting the slot due to link down event

[Niklas Cassel <cassel@kernel.org>]

Hello Mani,

On Thu, Apr 17, 2025 at 10:46:31PM +0530, Manivannan Sadhasivam via B4 Relay wrote:
> @@ -1571,6 +1652,9 @@ static irqreturn_t qcom_pcie_global_irq_thread(int irq, void *data)
>  		pci_unlock_rescan_remove();
>  
>  		qcom_pcie_icc_opp_update(pcie);
> +	} else if (FIELD_GET(PARF_INT_ALL_LINK_DOWN, status)) {
> +		dev_dbg(dev, "Received Link down event\n");
> +		pci_host_handle_link_down(pp->bridge);
>  	} else {
>  		dev_WARN_ONCE(dev, 1, "Received unknown event. INT_STATUS: 0x%08x\n",
>  			      status);

From debugging an unrelated problem, I noticed that dw-rockchip can
sometimes have both "link up" bit and "hot reset or link down" bit set
at the same time, when reading the status register.

Perhaps the link went down very quickly and then was established again
by the time the threaded IRQ handler gets to run.

Your code seems to do an if + else if.

Without knowing how the events work for your platforms, I would guess
that it should also be possible to have multiple events set.


In you code, if both LINK UP and hot reset/link down are set,
I would assume that you driver will not do the right thing.

Perhaps you want to swap the order? So that link down is handled first,
and then link up is handled. (If you convert to "if + if "instead of
"if + else if" that is.)


Kind regards,
Niklas