As per the PCIe base spec r5.0, section 5.2, Link Down event can happen
under any of the following circumstances:
1. Fundamental/Hot reset
2. Link disable transmission by upstream component
3. Moving from L2/L3 to L0
In those cases, Link Down causes some non-sticky DWC registers to loose the
state (like REBAR, etc...). So the drivers need to reinitialize them to
function properly once the link comes back again.
This is not a problem for drivers supporting PERST# IRQ, since they can
reinitialize the registers in the PERST# IRQ callback. But for the drivers
not supporting PERST#, there is no way they can reinitialize the registers
other than relying on Link Down IRQ received when the link goes down. So
let's add a DWC generic API dw_pcie_ep_linkdown() that reinitializes the
non-sticky registers and also notifies the EPF drivers about link going
down.
This API can also be used by the drivers supporting PERST# to handle the
scenario (2) mentioned above.
NOTE: For the sake of code organization, move the dw_pcie_ep_linkup()
definition just above dw_pcie_ep_linkdown().
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
drivers/pci/controller/dwc/pcie-designware-ep.c | 93 ++++++++++++++++---------
drivers/pci/controller/dwc/pcie-designware.h | 5 ++
2 files changed, 67 insertions(+), 31 deletions(-)
diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 3893a8c1a11c..5451057ca74b 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -14,18 +14,6 @@
#include <linux/pci-epc.h>
#include <linux/pci-epf.h>
-/**
- * dw_pcie_ep_linkup - Notify EPF drivers about link up event
- * @ep: DWC EP device
- */
-void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
-{
- struct pci_epc *epc = ep->epc;
-
- pci_epc_linkup(epc);
-}
-EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup);
-
/**
* dw_pcie_ep_init_notify - Notify EPF drivers about EPC initialization
* complete
@@ -672,6 +660,29 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
return 0;
}
+static void dw_pcie_ep_init_non_sticky_registers(struct dw_pcie *pci)
+{
+ unsigned int offset;
+ unsigned int nbars;
+ u32 reg, i;
+
+ offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
+
+ dw_pcie_dbi_ro_wr_en(pci);
+
+ if (offset) {
+ reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
+ nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
+ PCI_REBAR_CTRL_NBAR_SHIFT;
+
+ for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
+ dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
+ }
+
+ dw_pcie_setup(pci);
+ dw_pcie_dbi_ro_wr_dis(pci);
+}
+
/**
* dw_pcie_ep_init_registers - Initialize DWC EP specific registers
* @ep: DWC EP device
@@ -686,13 +697,11 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
struct dw_pcie_ep_func *ep_func;
struct device *dev = pci->dev;
struct pci_epc *epc = ep->epc;
- unsigned int offset, ptm_cap_base;
- unsigned int nbars;
+ u32 ptm_cap_base, reg;
u8 hdr_type;
u8 func_no;
- int i, ret;
void *addr;
- u32 reg;
+ int ret;
hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
PCI_HEADER_TYPE_MASK;
@@ -755,20 +764,8 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
if (ep->ops->init)
ep->ops->init(ep);
- offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
- dw_pcie_dbi_ro_wr_en(pci);
-
- if (offset) {
- reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
- nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
- PCI_REBAR_CTRL_NBAR_SHIFT;
-
- for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
- dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
- }
-
/*
* PTM responder capability can be disabled only after disabling
* PTM root capability.
@@ -785,9 +782,6 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
dw_pcie_dbi_ro_wr_dis(pci);
}
- dw_pcie_setup(pci);
- dw_pcie_dbi_ro_wr_dis(pci);
-
return 0;
err_remove_edma:
@@ -797,6 +791,43 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
}
EXPORT_SYMBOL_GPL(dw_pcie_ep_init_registers);
+/**
+ * dw_pcie_ep_linkup - Notify EPF drivers about Link Up event
+ * @ep: DWC EP device
+ */
+void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
+{
+ struct pci_epc *epc = ep->epc;
+
+ pci_epc_linkup(epc);
+}
+EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup);
+
+/**
+ * dw_pcie_ep_linkdown - Notify EPF drivers about Link Down event
+ * @ep: DWC EP device
+ *
+ * Non-sticky registers are also initialized before sending the notification to
+ * the EPF drivers. This is needed since the registers need to be initialized
+ * before the link comes back again.
+ */
+void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep)
+{
+ struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+ struct pci_epc *epc = ep->epc;
+
+ /*
+ * Initialize the non-sticky DWC registers as they would've reset post
+ * Link Down. This is specifically needed for drivers not supporting
+ * PERST# as they have no way to reinitialize the registers before the
+ * link comes back again.
+ */
+ dw_pcie_ep_init_non_sticky_registers(pci);
+
+ pci_epc_linkdown(epc);
+}
+EXPORT_SYMBOL_GPL(dw_pcie_ep_linkdown);
+
/**
* dw_pcie_ep_init - Initialize the endpoint device
* @ep: DWC EP device
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index f8e5431a207b..152969545b0a 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -668,6 +668,7 @@ static inline void __iomem *dw_pcie_own_conf_map_bus(struct pci_bus *bus,
#ifdef CONFIG_PCIE_DW_EP
void dw_pcie_ep_linkup(struct dw_pcie_ep *ep);
+void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep);
int dw_pcie_ep_init(struct dw_pcie_ep *ep);
int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep);
void dw_pcie_ep_init_notify(struct dw_pcie_ep *ep);
@@ -688,6 +689,10 @@ static inline void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
{
}
+static inline void dw_pcie_ep_linkdown(struct dw_pcie_ep *ep)
+{
+}
+
static inline int dw_pcie_ep_init(struct dw_pcie_ep *ep)
{
return 0;
--
2.25.1Hello Mani,
On Thu, Mar 14, 2024 at 08:53:46PM +0530, Manivannan Sadhasivam wrote:
> As per the PCIe base spec r5.0, section 5.2, Link Down event can happen
> under any of the following circumstances:
>
> 1. Fundamental/Hot reset
> 2. Link disable transmission by upstream component
> 3. Moving from L2/L3 to L0
>
> In those cases, Link Down causes some non-sticky DWC registers to loose the
> state (like REBAR, etc...). So the drivers need to reinitialize them to
> function properly once the link comes back again.
>
> This is not a problem for drivers supporting PERST# IRQ, since they can
> reinitialize the registers in the PERST# IRQ callback. But for the drivers
> not supporting PERST#, there is no way they can reinitialize the registers
> other than relying on Link Down IRQ received when the link goes down. So
> let's add a DWC generic API dw_pcie_ep_linkdown() that reinitializes the
> non-sticky registers and also notifies the EPF drivers about link going
> down.
>
> This API can also be used by the drivers supporting PERST# to handle the
> scenario (2) mentioned above.
>
> NOTE: For the sake of code organization, move the dw_pcie_ep_linkup()
> definition just above dw_pcie_ep_linkdown().
>
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> ---
> drivers/pci/controller/dwc/pcie-designware-ep.c | 93 ++++++++++++++++---------
> drivers/pci/controller/dwc/pcie-designware.h | 5 ++
> 2 files changed, 67 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> index 3893a8c1a11c..5451057ca74b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> @@ -14,18 +14,6 @@
> #include <linux/pci-epc.h>
> #include <linux/pci-epf.h>
>
> -/**
> - * dw_pcie_ep_linkup - Notify EPF drivers about link up event
> - * @ep: DWC EP device
> - */
> -void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
> -{
> - struct pci_epc *epc = ep->epc;
> -
> - pci_epc_linkup(epc);
> -}
> -EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup);
> -
> /**
> * dw_pcie_ep_init_notify - Notify EPF drivers about EPC initialization
> * complete
> @@ -672,6 +660,29 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
> return 0;
> }
>
> +static void dw_pcie_ep_init_non_sticky_registers(struct dw_pcie *pci)
> +{
> + unsigned int offset;
> + unsigned int nbars;
> + u32 reg, i;
> +
> + offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
> +
> + dw_pcie_dbi_ro_wr_en(pci);
> +
> + if (offset) {
> + reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
> + nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
> + PCI_REBAR_CTRL_NBAR_SHIFT;
> +
> + for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
> + dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
> + }
> +
> + dw_pcie_setup(pci);
> + dw_pcie_dbi_ro_wr_dis(pci);
> +}
> +
> /**
> * dw_pcie_ep_init_registers - Initialize DWC EP specific registers
> * @ep: DWC EP device
> @@ -686,13 +697,11 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> struct dw_pcie_ep_func *ep_func;
> struct device *dev = pci->dev;
> struct pci_epc *epc = ep->epc;
> - unsigned int offset, ptm_cap_base;
> - unsigned int nbars;
> + u32 ptm_cap_base, reg;
> u8 hdr_type;
> u8 func_no;
> - int i, ret;
> void *addr;
> - u32 reg;
> + int ret;
>
> hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
> PCI_HEADER_TYPE_MASK;
> @@ -755,20 +764,8 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> if (ep->ops->init)
> ep->ops->init(ep);
>
> - offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
> ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
>
> - dw_pcie_dbi_ro_wr_en(pci);
> -
> - if (offset) {
> - reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
> - nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
> - PCI_REBAR_CTRL_NBAR_SHIFT;
> -
> - for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
> - dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
> - }
> -
> /*
> * PTM responder capability can be disabled only after disabling
> * PTM root capability.
> @@ -785,9 +782,6 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> dw_pcie_dbi_ro_wr_dis(pci);
> }
>
> - dw_pcie_setup(pci);
> - dw_pcie_dbi_ro_wr_dis(pci);
> -
Your previous series had:
- dw_pcie_setup(pci);
- dw_pcie_dbi_ro_wr_dis(pci);
+ dw_pcie_ep_init_non_sticky_registers(pci);
Here.
I tested this series, but it did not work for me (the Resizable BARs did
not get resized) since you removed the call to
dw_pcie_ep_init_non_sticky_registers().
By readding the call to dw_pcie_ep_init_non_sticky_registers(),
the BARs get Resized again.
BTW do you have a git branch with both your series somewhere?
(Possibly even rebased on
https://lore.kernel.org/linux-pci/20240320113157.322695-1-cassel@kernel.org/T/#t
like you suggested in your other mail.)
Kind regards,
Niklas
On Wed, Mar 27, 2024 at 07:06:30PM +0100, Niklas Cassel wrote:
> Hello Mani,
>
> On Thu, Mar 14, 2024 at 08:53:46PM +0530, Manivannan Sadhasivam wrote:
> > As per the PCIe base spec r5.0, section 5.2, Link Down event can happen
> > under any of the following circumstances:
> >
> > 1. Fundamental/Hot reset
> > 2. Link disable transmission by upstream component
> > 3. Moving from L2/L3 to L0
> >
> > In those cases, Link Down causes some non-sticky DWC registers to loose the
> > state (like REBAR, etc...). So the drivers need to reinitialize them to
> > function properly once the link comes back again.
> >
> > This is not a problem for drivers supporting PERST# IRQ, since they can
> > reinitialize the registers in the PERST# IRQ callback. But for the drivers
> > not supporting PERST#, there is no way they can reinitialize the registers
> > other than relying on Link Down IRQ received when the link goes down. So
> > let's add a DWC generic API dw_pcie_ep_linkdown() that reinitializes the
> > non-sticky registers and also notifies the EPF drivers about link going
> > down.
> >
> > This API can also be used by the drivers supporting PERST# to handle the
> > scenario (2) mentioned above.
> >
> > NOTE: For the sake of code organization, move the dw_pcie_ep_linkup()
> > definition just above dw_pcie_ep_linkdown().
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> > drivers/pci/controller/dwc/pcie-designware-ep.c | 93 ++++++++++++++++---------
> > drivers/pci/controller/dwc/pcie-designware.h | 5 ++
> > 2 files changed, 67 insertions(+), 31 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > index 3893a8c1a11c..5451057ca74b 100644
> > --- a/drivers/pci/controller/dwc/pcie-designware-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
> > @@ -14,18 +14,6 @@
> > #include <linux/pci-epc.h>
> > #include <linux/pci-epf.h>
> >
> > -/**
> > - * dw_pcie_ep_linkup - Notify EPF drivers about link up event
> > - * @ep: DWC EP device
> > - */
> > -void dw_pcie_ep_linkup(struct dw_pcie_ep *ep)
> > -{
> > - struct pci_epc *epc = ep->epc;
> > -
> > - pci_epc_linkup(epc);
> > -}
> > -EXPORT_SYMBOL_GPL(dw_pcie_ep_linkup);
> > -
> > /**
> > * dw_pcie_ep_init_notify - Notify EPF drivers about EPC initialization
> > * complete
> > @@ -672,6 +660,29 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
> > return 0;
> > }
> >
> > +static void dw_pcie_ep_init_non_sticky_registers(struct dw_pcie *pci)
> > +{
> > + unsigned int offset;
> > + unsigned int nbars;
> > + u32 reg, i;
> > +
> > + offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
> > +
> > + dw_pcie_dbi_ro_wr_en(pci);
> > +
> > + if (offset) {
> > + reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
> > + nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
> > + PCI_REBAR_CTRL_NBAR_SHIFT;
> > +
> > + for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
> > + dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
> > + }
> > +
> > + dw_pcie_setup(pci);
> > + dw_pcie_dbi_ro_wr_dis(pci);
> > +}
> > +
> > /**
> > * dw_pcie_ep_init_registers - Initialize DWC EP specific registers
> > * @ep: DWC EP device
> > @@ -686,13 +697,11 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> > struct dw_pcie_ep_func *ep_func;
> > struct device *dev = pci->dev;
> > struct pci_epc *epc = ep->epc;
> > - unsigned int offset, ptm_cap_base;
> > - unsigned int nbars;
> > + u32 ptm_cap_base, reg;
> > u8 hdr_type;
> > u8 func_no;
> > - int i, ret;
> > void *addr;
> > - u32 reg;
> > + int ret;
> >
> > hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
> > PCI_HEADER_TYPE_MASK;
> > @@ -755,20 +764,8 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> > if (ep->ops->init)
> > ep->ops->init(ep);
> >
> > - offset = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_REBAR);
> > ptm_cap_base = dw_pcie_ep_find_ext_capability(pci, PCI_EXT_CAP_ID_PTM);
> >
> > - dw_pcie_dbi_ro_wr_en(pci);
> > -
> > - if (offset) {
> > - reg = dw_pcie_readl_dbi(pci, offset + PCI_REBAR_CTRL);
> > - nbars = (reg & PCI_REBAR_CTRL_NBAR_MASK) >>
> > - PCI_REBAR_CTRL_NBAR_SHIFT;
> > -
> > - for (i = 0; i < nbars; i++, offset += PCI_REBAR_CTRL)
> > - dw_pcie_writel_dbi(pci, offset + PCI_REBAR_CAP, 0x0);
> > - }
> > -
> > /*
> > * PTM responder capability can be disabled only after disabling
> > * PTM root capability.
> > @@ -785,9 +782,6 @@ int dw_pcie_ep_init_registers(struct dw_pcie_ep *ep)
> > dw_pcie_dbi_ro_wr_dis(pci);
> > }
> >
> > - dw_pcie_setup(pci);
> > - dw_pcie_dbi_ro_wr_dis(pci);
> > -
>
> Your previous series had:
>
> - dw_pcie_setup(pci);
> - dw_pcie_dbi_ro_wr_dis(pci);
> + dw_pcie_ep_init_non_sticky_registers(pci);
>
> Here.
> I tested this series, but it did not work for me (the Resizable BARs did
> not get resized) since you removed the call to
> dw_pcie_ep_init_non_sticky_registers().
>
> By readding the call to dw_pcie_ep_init_non_sticky_registers(),
> the BARs get Resized again.
>
>
Ah, looks like rebase has gone bad. Will fix it in v2.
> BTW do you have a git branch with both your series somewhere?
> (Possibly even rebased on
> https://lore.kernel.org/linux-pci/20240320113157.322695-1-cassel@kernel.org/T/#t
> like you suggested in your other mail.)
>
There it is: https://git.codelinaro.org/manivannan.sadhasivam/linux/-/tree/b4/pci-epf-rework
- Mani
--
மணிவண்ணன் சதாசிவம்
On Thu, Mar 14, 2024 at 08:53:46PM +0530, Manivannan Sadhasivam wrote: > As per the PCIe base spec r5.0, section 5.2, Link Down event can happen > under any of the following circumstances: > > 1. Fundamental/Hot reset > 2. Link disable transmission by upstream component > 3. Moving from L2/L3 to L0 > > In those cases, Link Down causes some non-sticky DWC registers to loose the > state (like REBAR, etc...). So the drivers need to reinitialize them to > function properly once the link comes back again. > > This is not a problem for drivers supporting PERST# IRQ, since they can > reinitialize the registers in the PERST# IRQ callback. But for the drivers > not supporting PERST#, there is no way they can reinitialize the registers > other than relying on Link Down IRQ received when the link goes down. So > let's add a DWC generic API dw_pcie_ep_linkdown() that reinitializes the > non-sticky registers and also notifies the EPF drivers about link going > down. > > This API can also be used by the drivers supporting PERST# to handle the > scenario (2) mentioned above. > > NOTE: For the sake of code organization, move the dw_pcie_ep_linkup() > definition just above dw_pcie_ep_linkdown(). > > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org> > --- Reviewed-by: Niklas Cassel <cassel@kernel.org>
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