Re: [PATCH v2 2/3] PCI: cadence: Use DT bindings to set PHY latencies
From: Christian Gmeiner
Date: Tue May 30 2023 - 04:20:43 EST
Am Do., 4. Mai 2023 um 13:33 Uhr schrieb Verma, Achal <a-verma1@xxxxxx>:
>
>
>
> On 4/27/2023 11:20 AM, Dominic Rath wrote:
> > From: Alexander Bahle <bahle@xxxxxxxxxxxxxxx>
> >
> > Use optional "tx-phy-latency-ps" and "rx-phy-latency-ps"
> > DeviceTree bindings to set the CDNS_PCIE_LM_PTM_LAT_PARAM(_IDX)
> > register(s) during PCIe host and endpoint setup.
> >
> > The properties are lists of uint32 PHY latencies in picoseconds for
> > every supported speed starting at PCIe Gen1, e.g.:
> >
> > tx-phy-latency-ps = <100000 200000>; /* Gen1: 100ns, Gen2: 200ns */
> > rx-phy-latency-ps = <150000 250000>; /* Gen1: 150ns, Gen2: 250ns */
> >
> > There should be a value for every supported speed, otherwise a info
> > message is emitted to let users know that the PTM timestamps from this
> > PCIe device may not be precise enough for some applications.
> >
> > Signed-off-by: Alexander Bahle <bahle@xxxxxxxxxxxxxxx>
> > Signed-off-by: Dominic Rath <rath@xxxxxxxxxxxxxxx>
> > ---
> > .../pci/controller/cadence/pcie-cadence-ep.c | 2 +
> > .../controller/cadence/pcie-cadence-host.c | 1 +
> > drivers/pci/controller/cadence/pcie-cadence.c | 92 +++++++++++++++++++
> > drivers/pci/controller/cadence/pcie-cadence.h | 23 +++++
> > 4 files changed, 118 insertions(+)
> >
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > index b8b655d4047e..6e39126922d1 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > @@ -664,6 +664,8 @@ int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep)
> > }
> > pcie->mem_res = res;
> >
> > + cdns_pcie_init_ptm_phy_latency(dev, pcie);
> > +
> > ep->max_regions = CDNS_PCIE_MAX_OB;
> > of_property_read_u32(np, "cdns,max-outbound-regions", &ep->max_regions);
> >
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence-host.c b/drivers/pci/controller/cadence/pcie-cadence-host.c
> > index 940c7dd701d6..8933002f828e 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence-host.c
> > +++ b/drivers/pci/controller/cadence/pcie-cadence-host.c
> > @@ -510,6 +510,7 @@ int cdns_pcie_host_setup(struct cdns_pcie_rc *rc)
> > cdns_pcie_detect_quiet_min_delay_set(&rc->pcie);
> >
> > cdns_pcie_host_enable_ptm_response(pcie)
> Hi Dominic,
> Shouldn't cdns_pcie_init_ptm_phy_latency() called before
> cdns_pcie_host_enable_ptm_response(), enabling host to reply PTM
> requests. However host could receive PTM requests later only after
> cdns_pcie_start_link().
Good catch!
> > + cdns_pcie_init_ptm_phy_latency(dev, pcie);
> >
> > ret = cdns_pcie_start_link(pcie);
> > if (ret) {
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence.c b/drivers/pci/controller/cadence/pcie-cadence.c
> > index 13c4032ca379..1a282ed9b888 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence.c
> > +++ b/drivers/pci/controller/cadence/pcie-cadence.c
> > @@ -5,8 +5,100 @@
> >
> > #include <linux/kernel.h>
> >
> > +#include "../../pci.h"
> > #include "pcie-cadence.h"
> >
> > +void cdns_pcie_set_ptm_phy_latency_param(struct cdns_pcie *pcie, bool rx,
> > + u32 speed_index, u32 latency)
> > +{
> > + u32 val;
> > +
> > + /* Set the speed index */
> > + val = cdns_pcie_readl(pcie, CDNS_PCIE_LM_PTM_LAT_PARAM_IDX);
> > + val = ((val & ~CDNS_PCIE_LM_PTM_LAT_PARAM_IDX_PTMLATIN_MASK) |
> > + CDNS_PCIE_LM_PTM_LAT_PARAM_IDX_PTMLATIN(speed_index));
> > + cdns_pcie_writel(pcie, CDNS_PCIE_LM_PTM_LAT_PARAM_IDX, val);
> > +
> > + val = cdns_pcie_readl(pcie, CDNS_PCIE_LM_PTM_LAT_PARAM);
> > + if (rx) {
> > + /* Set the RX direction latency */
> > + val = ((val & ~CDNS_PCIE_LM_PTM_LAT_PARAM_PTMRXLAT_MASK) |
> > + CDNS_PCIE_LM_PTM_LAT_PARAM_PTMRXLAT(latency));
> > + } else {
> > + /* Set TX direction latency */
> > + val = ((val & ~CDNS_PCIE_LM_PTM_LAT_PARAM_PTMTXLAT_MASK) |
> > + CDNS_PCIE_LM_PTM_LAT_PARAM_PTMTXLAT(latency));
> > + }
> > + cdns_pcie_writel(pcie, CDNS_PCIE_LM_PTM_LAT_PARAM, val);
> > +}
> > +
> > +static int cdns_pcie_set_ptm_phy_latency(struct device *dev, struct cdns_pcie *pcie,
> > + bool rx, const char *key)
> > +{
> > + struct device_node *np;
> > + int max_link_speed;
> > + int param_count;
> > + u32 latency;
> > + int ret;
> > + int i;
> > +
> > + /* Do nothing if there is no phy */
> > + if (pcie->phy_count < 1)
> > + return 0;
> > +
> > + np = dev->of_node;
> > + max_link_speed = of_pci_get_max_link_speed(np);
> > + if (max_link_speed < 1)
> > + return -EINVAL;
> > +
> > + /* Only check and use params of the first phy */
> > + np = pcie->phy[0]->dev.of_node;
> > + param_count = of_property_count_u32_elems(np, key);
> > + if (param_count < 0 || param_count < max_link_speed) {
> > + dev_info(dev,
> > + "PTM: no %s set for one or more speeds: %d\n",
> > + key, param_count);
> > + }
> > +
> > + /* Don't set param for unsupported speed */
> > + if (param_count > max_link_speed)
> > + param_count = max_link_speed;
> > +
> > + for (i = 0; i < param_count; i++) {
> > + ret = of_property_read_u32_index(np, key, i, &latency);
> > + if (ret != 0) {
> > + dev_err(dev, "failed to read PTM latency for speed %d from %s\n",
> > + i, key);
> > + return ret;
> > + }
> > +
> > + /* convert ps to ns */
> > + latency /= 1000;
> > +
> > + cdns_pcie_set_ptm_phy_latency_param(pcie, rx,
> > + i, latency);
> > +
> > + dev_dbg(dev, "PTM: %s phy latency Gen.%d: %uns\n",
> > + rx ? "rx" : "tx", i+1, latency);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +int cdns_pcie_init_ptm_phy_latency(struct device *dev, struct cdns_pcie *pcie)
> > +{
> > + int ret;
> > +
> > + ret = cdns_pcie_set_ptm_phy_latency(dev, pcie, false,
> > + "tx-phy-latency-ps");
> > + if (ret)
> > + return ret;
> > +
> > + ret = cdns_pcie_set_ptm_phy_latency(dev, pcie, true,
> > + "rx-phy-latency-ps");
> > + return ret;
> > +}
> > +
> > void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie)
> > {
> > u32 delay = 0x3;
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence.h b/drivers/pci/controller/cadence/pcie-cadence.h
> > index 190786e47df9..483b957a8212 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence.h
> > +++ b/drivers/pci/controller/cadence/pcie-cadence.h
> > @@ -120,6 +120,26 @@
> > #define CDNS_PCIE_LM_PTM_CTRL (CDNS_PCIE_LM_BASE + 0x0da8)
> > #define CDNS_PCIE_LM_TPM_CTRL_PTMRSEN BIT(17)
> >
> > +/* PTM Latency Parameters Index Register */
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_IDX \
> > + (CDNS_PCIE_LM_BASE + 0x0db0)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_IDX_PTMLATIN_MASK \
> > + GENMASK(3, 0)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_IDX_PTMLATIN(a) \
> > + (((a) << 0) & CDNS_PCIE_LM_PTM_LAT_PARAM_IDX_PTMLATIN_MASK)
> > +
> > +/* PTM Latency Parameters Register */
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM \
> > + (CDNS_PCIE_LM_BASE + 0x0db4)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_PTMTXLAT_MASK \
> > + GENMASK(9, 0)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_PTMTXLAT(a) \
> > + (((a) << 0) & CDNS_PCIE_LM_PTM_LAT_PARAM_PTMTXLAT_MASK)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_PTMRXLAT_MASK \
> > + GENMASK(19, 10)
> > +#define CDNS_PCIE_LM_PTM_LAT_PARAM_PTMRXLAT(b) \
> > + (((b) << 10) & CDNS_PCIE_LM_PTM_LAT_PARAM_PTMRXLAT_MASK)
> > +
> > /*
> > * Endpoint Function Registers (PCI configuration space for endpoint functions)
> > */
> > @@ -541,6 +561,9 @@ static inline int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep)
> > #endif
> >
> > void cdns_pcie_detect_quiet_min_delay_set(struct cdns_pcie *pcie);
> > +void cdns_pcie_set_ptm_phy_latency_param(struct cdns_pcie *pcie, bool rx,
> > + u32 speed_index, u32 latency);
> > +int cdns_pcie_init_ptm_phy_latency(struct device *dev, struct cdns_pcie *pcie);
> >
> > void cdns_pcie_set_outbound_region(struct cdns_pcie *pcie, u8 busnr, u8 fn,
> > u32 r, bool is_io,
> Acked-by: Achal Verma <a-verma1@xxxxxx>
With the suggested change:
Reviewed-by: Christian Gmeiner <christian.gmeiner@xxxxxxxxx>
--
greets
--
Christian Gmeiner, MSc
https://christian-gmeiner.info/privacypolicy