On Fri, Nov 01, 2024 at 10:26:38AM -0500, Bjorn Andersson wrote:
> On Fri, Nov 01, 2024 at 05:04:12PM GMT, Krishna chaitanya chundru wrote:
> > If the vendor drivers can detect the Link up event using mechanisms
> > such as Link up IRQ and can the driver can enumerate downstream devices
> > instead of waiting here, then waiting for Link up during probe is not
> > needed here, which optimizes the boot time.
> >
> > So skip waiting for link to be up if the driver supports 'linkup_irq'.
> >
> > Signed-off-by: Krishna chaitanya chundru <quic_krichai@xxxxxxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pcie-designware-host.c | 10 ++++++++--
> > drivers/pci/controller/dwc/pcie-designware.h | 1 +
> > 2 files changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > index 3e41865c7290..26418873ce14 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > @@ -530,8 +530,14 @@ int dw_pcie_host_init(struct dw_pcie_rp *pp)
> > goto err_remove_edma;
> > }
> >
> > - /* Ignore errors, the link may come up later */
> > - dw_pcie_wait_for_link(pci);
> > + /*
> > + * Note: The link up delay is skipped only when a link up IRQ is present.
> > + * This flag should not be used to bypass the link up delay for arbitrary
> > + * reasons.
>
> Perhaps by improving the naming of the variable, you don't need 3 lines
> of comment describing the conditional.
>
> > + */
> > + if (!pp->linkup_irq)
> > + /* Ignore errors, the link may come up later */
>
> Does this mean that we will be able to start handling these errors?
>
> > + dw_pcie_wait_for_link(pci);
> >
> > bridge->sysdata = pp;
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > index 347ab74ac35a..539c6d106bb0 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > @@ -379,6 +379,7 @@ struct dw_pcie_rp {
> > bool use_atu_msg;
> > int msg_atu_index;
> > struct resource *msg_res;
> > + bool linkup_irq;
>
> Please name this for what it is, rather than some property from which
> some other decision should be derived. (And then you need a comment to
> describe how people should interpret and use it)
>
> Also, "linkup_irq" sound like an int carrying the interrupt number, not
> a boolean.
>
>
> Please call it "use_async_linkup", "use_linkup_irq" or something.
>
"use_linkup_irq" sounds good to me. But I do like to keep the note above as
there were incidents that people tried to avoid this delay as a "workaround" to
unrelated problems.
- Mani
--
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