Re: [PATCH v7 0/8] Expose and manage PCI device reset

From: Amey Narkhede
Date: Tue Jun 08 2021 - 11:46:17 EST

On 21/06/08 12:05PM, Enrico Weigelt, metux IT consult wrote:
> On 08.06.21 07:48, Amey Narkhede wrote:
> Hi,
> > PCI and PCIe devices may support a number of possible reset mechanisms
> > for example Function Level Reset (FLR) provided via Advanced Feature or
> > PCIe capabilities, Power Management reset, bus reset, or device specific reset.
> > Currently the PCI subsystem creates a policy prioritizing these reset methods
> > which provides neither visibility nor control to userspace.
> Since I've got a current use case for that - could you perhaps tell more
> about the whole pci device reset mechanisms ?
> In my case I've got a board that wires reset lines to the soc's gpios.
> Not sure how exactly to qualify this, but I guess it would count as a
> bus wide reset.
> Now the big question for me is how to implement that in a board specific
> platform driver (which already does setup of gpios and other attached
> devices), so we can reset the card in slot X in a generic way.
> Any help highly appreciated.
> --mtx
In case of bus reset(pci_reset_secondary_bus()), it uses bridge control
register to assert reset on bus so I think it should out of the box but
not 100% sure about it.