| Message ID | 20230404174141.4091634-1-ajayagarwal@google.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | PCI: dwc: Allow platform driver to skip the wait for link | expand |
On Tue, Apr 04, 2023 at 11:11:41PM +0530, Ajay Agarwal wrote: > Currently as a part of device probe, the driver waits for the > link to come up for up to 1 second. If the link training is not > enabled by default or as a part of host_init, then this wait for > the link can be skipped to save the 1 second of wait time. > > Allow the platform driver to skip this wait for the link up by > setting a flag `skip_wait_for_link`. This flag will be false by > default, thereby preserving the legacy behavior for existing > platform drivers. > > Signed-off-by: Ajay Agarwal <ajayagarwal@google.com> > --- > drivers/pci/controller/dwc/pcie-designware-host.c | 9 +++++++-- > drivers/pci/controller/dwc/pcie-designware.h | 1 + > 2 files changed, 8 insertions(+), 2 deletions(-) A previous patch handles this change, dropping this one, please chime in in this thread if needed: https://lore.kernel.org/linux-pci/ZC12lN9Cs0QlPhVh@lpieralisi > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c > index 9952057c8819..3425eb17b467 100644 > --- a/drivers/pci/controller/dwc/pcie-designware-host.c > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c > @@ -491,8 +491,13 @@ 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); > + /* > + * If the platform driver sets `skip_wait_for_link` because it knows the > + * link will not be up, do not wait for it. Save 1 sec of wait time. > + * Else, test for the link. Ignore errors, the link may come up later > + */ > + if (!pp->skip_wait_for_link) > + 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 79713ce075cc..f8f6dad5c948 100644 > --- a/drivers/pci/controller/dwc/pcie-designware.h > +++ b/drivers/pci/controller/dwc/pcie-designware.h > @@ -297,6 +297,7 @@ struct dw_pcie_host_ops { > struct dw_pcie_rp { > bool has_msi_ctrl:1; > bool cfg0_io_shared:1; > + bool skip_wait_for_link:1; > u64 cfg0_base; > void __iomem *va_cfg0_base; > u32 cfg0_size; > -- > 2.40.0.348.gf938b09366-goog >
diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c index 9952057c8819..3425eb17b467 100644 --- a/drivers/pci/controller/dwc/pcie-designware-host.c +++ b/drivers/pci/controller/dwc/pcie-designware-host.c @@ -491,8 +491,13 @@ 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); + /* + * If the platform driver sets `skip_wait_for_link` because it knows the + * link will not be up, do not wait for it. Save 1 sec of wait time. + * Else, test for the link. Ignore errors, the link may come up later + */ + if (!pp->skip_wait_for_link) + 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 79713ce075cc..f8f6dad5c948 100644 --- a/drivers/pci/controller/dwc/pcie-designware.h +++ b/drivers/pci/controller/dwc/pcie-designware.h @@ -297,6 +297,7 @@ struct dw_pcie_host_ops { struct dw_pcie_rp { bool has_msi_ctrl:1; bool cfg0_io_shared:1; + bool skip_wait_for_link:1; u64 cfg0_base; void __iomem *va_cfg0_base; u32 cfg0_size;
Currently as a part of device probe, the driver waits for the link to come up for up to 1 second. If the link training is not enabled by default or as a part of host_init, then this wait for the link can be skipped to save the 1 second of wait time. Allow the platform driver to skip this wait for the link up by setting a flag `skip_wait_for_link`. This flag will be false by default, thereby preserving the legacy behavior for existing platform drivers. Signed-off-by: Ajay Agarwal <ajayagarwal@google.com> --- drivers/pci/controller/dwc/pcie-designware-host.c | 9 +++++++-- drivers/pci/controller/dwc/pcie-designware.h | 1 + 2 files changed, 8 insertions(+), 2 deletions(-)