Re: Questions on PCI express AER support in HBA driver

Re: Questions on PCI express AER support in HBA driver

[Allexio Ju]

On 1/21/07, Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> > >From the document "The PCI Express AER Driver Guide" that you wrote,
> > I've got an impression that SCSI LLD driver needs to have
> > (*link_reset). Isn't this callback also required if the driver
> > supports PCIe AER?
> link_reset was deleted in my final AER patch. My objective is
> to keep the callbacks simple, so driver developers are willing to
> add AER support.
>
> Linas said he would remove it from the definition of pci_error_handlers
> only after a long time that noboday really uses it.
So, instead of having (*reset_link) in pcie_port_service_driver
structure, I just need (*link_reset) in pci_error_handler structure to
support  PCIe AER. Is this correct understanding?

Allexio

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Re: Questions on PCI express AER support in HBA driver

[Zhang, Yanmin]

On Mon, 2007-01-22 at 05:59 -0800, Allexio Ju wrote:
> On 1/21/07, Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> > > >From the document "The PCI Express AER Driver Guide" that you wrote,
> > > I've got an impression that SCSI LLD driver needs to have
> > > (*link_reset). Isn't this callback also required if the driver
> > > supports PCIe AER?
> > link_reset was deleted in my final AER patch. My objective is
> > to keep the callbacks simple, so driver developers are willing to
> > add AER support.
> >
> > Linas said he would remove it from the definition of pci_error_handlers
> > only after a long time that noboday really uses it.
> So, instead of having (*reset_link) in pcie_port_service_driver
> structure, I just need (*link_reset) in pci_error_handler structure to
> support  PCIe AER. Is this correct understanding?
Sorry, the definition names are confusing which I tried to avoid.

1) pcie_port_service_driver is service driver of port, not end-point devices.
SCSI LLD driver should be end-point devices, so you needn't use reset_link
in pcie_port_service_driver.
2) (*link_reset) in pci_error_handler structure was obsolete. Pls. don't use it
at all. Originally, this callback was to tell driver that a pci express link was
reset. Its problem is error_detected might return PCI_ERS_RESULT_NEED_RESET also
which means next recovery step is slot_reset. In addition, I want to keep the
error recovery steps simple, so driver developers are happy to add callbacks in
drivers. Another reason is the specific driver should be compatible for pci and
pci-express together. If we use link_reset in pci_error_handler, the codes might
be not compatible.

Typically, the callbacks in pci-e (or just pci) drivers could be:
1) pci_ers_result_t (*error_detected)(struct pci_dev *dev,
		enum pci_channel_state error);
2) pci_ers_result_t (*slot_reset)(struct pci_dev *dev);
3) void (*resume)(struct pci_dev *dev);

Thanks,
Yanmin

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Re: Questions on PCI express AER support in HBA driver

[Allexio Ju]

Hi,

On 1/22/07, Zhang, Yanmin <yanmin_zhang@linux.intel.com> wrote:
> 1) pcie_port_service_driver is service driver of port, not end-point devices.
> SCSI LLD driver should be end-point devices, so you needn't use reset_link
> in pcie_port_service_driver.
Great. Thank you for clarification.

> 2) (*link_reset) in pci_error_handler structure was obsolete. Pls. don't use it
> at all. Originally, this callback was to tell driver that a pci express link was
> reset. Its problem is error_detected might return PCI_ERS_RESULT_NEED_RESET also
> which means next recovery step is slot_reset. In addition, I want to keep the
> error recovery steps simple, so driver developers are happy to add callbacks in
> drivers. Another reason is the specific driver should be compatible for pci and
> pci-express together. If we use link_reset in pci_error_handler, the codes might
> be not compatible.
Understood and it make sense. Thank you for detail description.

> Typically, the callbacks in pci-e (or just pci) drivers could be:
> 1) pci_ers_result_t (*error_detected)(struct pci_dev *dev,
>                enum pci_channel_state error);
> 2) pci_ers_result_t (*slot_reset)(struct pci_dev *dev);
> 3) void (*resume)(struct pci_dev *dev);
Understood.

Thank you,

Allexio

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