Re: [PATCH v2 1/1] PCI: pciehp: Skip DLLSC handling if DPC is triggered
From: Sinan Kaya
Date: Thu Mar 18 2021 - 11:37:00 EST
On 3/17/2021 4:02 PM, Kuppuswamy, Sathyanarayanan wrote:
> My point is, there is no race in OS handlers (pciehp_ist() vs
> pcie_do_recovery())
> However, Sinan wrote in
>> 2018 that one of the issues with hotplug versus DPC is that pciehp
>> may turn off slot power and thereby foil DPC recovery. (Power off =
>> cold reset, whereas DPC recovery = warm reset.) This can occur
>> as well if DPC is handled by firmware.
It has been a while...
If I remember correctly, there is no race condition if the platform
handles DPC and HP interrupts on the same MSI vector.
If HP and DPC interrupts are handled as MSI-x interrupts, these can
fire out of order and can cause problems for each one.
I hope it helps.