On Mon, Jul 17, 2023 at 02:36:19PM -0400, Frank Li wrote:
> On Mon, Jul 17, 2023 at 10:15:26PM +0530, Manivannan Sadhasivam wrote:
> > On Wed, Apr 19, 2023 at 12:41:17PM -0400, Frank Li wrote:
> > > Introduced helper function dw_pcie_get_ltssm to retrieve SMLH_LTSS_STATE.
> > > Added API pme_turn_off and exit_from_l2 for managing L2/L3 state transitions.
> > >
> > > Typical L2 entry workflow:
> > >
> > > 1. Transmit PME turn off signal to PCI devices.
> > > 2. Await link entering L2_IDLE state.
> >
> > AFAIK, typical workflow is to wait for PME_To_Ack.
>
> 1 Already wait for PME_to_ACK, 2, just wait for link actual enter L2.
> I think PCI RC needs some time to set link enter L2 after get ACK from
> PME.
>
> >
> > > 3. Transition Root complex to D3 state.
> > >
> > > Typical L2 exit workflow:
> > >
> > > 1. Transition Root complex to D0 state.
> > > 2. Issue exit from L2 command.
> > > 3. Reinitialize PCI host.
> > > 4. Wait for link to become active.
> > >
> > > Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
> > > ---
> > > Change from v2 to v3:
> > > - Basic rewrite whole patch according rob herry suggestion.
> > > put common function into dwc, so more soc can share the same logic.
> > >
> > > .../pci/controller/dwc/pcie-designware-host.c | 80 +++++++++++++++++++
> > > drivers/pci/controller/dwc/pcie-designware.h | 28 +++++++
> > > 2 files changed, 108 insertions(+)
> > >
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > index 9952057c8819..ef6869488bde 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> > > +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> > > @@ -8,6 +8,7 @@
> > > * Author: Jingoo Han <jg1.han@xxxxxxxxxxx>
> > > */
> > >
> > > +#include <linux/iopoll.h>
> > > #include <linux/irqchip/chained_irq.h>
> > > #include <linux/irqdomain.h>
> > > #include <linux/msi.h>
> > > @@ -807,3 +808,82 @@ int dw_pcie_setup_rc(struct dw_pcie_rp *pp)
> > > return 0;
> > > }
> > > EXPORT_SYMBOL_GPL(dw_pcie_setup_rc);
> > > +
> > > +/*
> > > + * There are for configuring host controllers, which are bridges *to* PCI devices
> > > + * but are not PCI devices themselves.
> >
> > None of the functions applicable to the devices. So there is no need for this
> > comment.
>
> I copy comments in drivers/pci/controller/dwc/pcie-designware.c.
>
> /*
> * These interfaces resemble the pci_find_*capability() interfaces, but these
> * are for configuring host controllers, which are bridges *to* PCI devices but
> * are not PCI devices themselves.
> */
> static u8 __dw_pcie_find_next_cap(struct dw_pcie *pci, u8 cap_ptr,
> u8 cap)
>
>
> I think it is reasonalble because it is too similar with standard API
> pci_set_power_state();
>
Ok, then please add this API similarity in the comment as like
__dw_pcie_find_next_cap(). Also change "There" to "These".
> >
> > > + */
> > > +static void dw_pcie_set_dstate(struct dw_pcie *pci, u32 dstate)
> >
> > Please use pci_power_t defines for dstates.
>
> Although dwc use the same define, it is difference things.
>
Sorry, what difference? Could you please clarify?
> >
> > > +{
> > > + u8 offset = dw_pcie_find_capability(pci, PCI_CAP_ID_PM);
> > > + u32 val;
> > > +
> > > + val = dw_pcie_readw_dbi(pci, offset + PCI_PM_CTRL);
> >
> > Please use PCI accessors for accessing spec compliant registers.
>
> According to comments in pcie-designware.c, it is difference concept
> even though register define is the same as PCI spec. It was used to
> control root bridges.
>
Ah, I got slightly confused. This is fine.
> >
> > > + val &= ~PCI_PM_CTRL_STATE_MASK;
> > > + val |= dstate;
> > > + dw_pcie_writew_dbi(pci, offset + PCI_PM_CTRL, val);
> > > +}
> > > +
> > > +int dw_pcie_suspend_noirq(struct dw_pcie *pci)
> > > +{
> > > + u32 val;
> > > + int ret;
> > > +
> > > + if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_ACT)
> > > + return 0;
> > > +
> > > + pci->pp.ops->pme_turn_off(&pci->pp);
> >
> > You should first check for the existence of the callback before invoking. This
> > applies to all callbacks in this patch.
>
> Yes, I will update.
>
> >
> > > +
> > > + /*
> > > + * PCI Express Base Specification Rev 4.0
> > > + * 5.3.3.2.1 PME Synchronization
> > > + * Recommand 1ms to 10ms timeout to check L2 ready
> > > + */
> > > + ret = read_poll_timeout(dw_pcie_get_ltssm, val, val == DW_PCIE_LTSSM_L2_IDLE,
> > > + 100, 10000, false, pci);
> >
> > Is there no way to wait for PME_To_Ack TLP?
>
>
> Suppose PME_turn_off should wait for ACK before return.
Ok. I didn't see this behavior in the spec, hence curious.
> Here, just make sure Link enter L2 status. Hardware need some time to put
> link to L2 after get ACK from bus, even it is very short generally.
>
Fine then. But can we check for PM_LINKST_IN_L2 SII System Information Interface
(SII) instead of LTSSM state?
> >
> > > + if (ret) {
> > > + dev_err(pci->dev, "PCIe link enter L2 timeout! ltssm = 0x%x\n", val);
> > > + return ret;
> > > + }
> > > +
> > > + dw_pcie_set_dstate(pci, 0x3);
> > > +
> > > + pci->suspended = true;
> > > +
> > > + return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dw_pcie_suspend_noirq);
> > > +
> > > +int dw_pcie_resume_noirq(struct dw_pcie *pci)
> > > +{
> > > + int ret;
> > > +
> > > + if (!pci->suspended)
> > > + return 0;
> > > +
> > > + pci->suspended = false;
> > > +
> > > + dw_pcie_set_dstate(pci, 0x0);
> > > +
> > > + pci->pp.ops->exit_from_l2(&pci->pp);
> > > +
> > > + /* delay 10 ms to access EP */
> >
> > Is this delay as part of the DWC spec? If so, please quote the section.
> >
> > > + mdelay(10);
> > > +
> > > + ret = pci->pp.ops->host_init(&pci->pp);
> > > + if (ret) {
> > > + dev_err(pci->dev, "ls_pcie_host_init failed! ret = 0x%x\n", ret);
> >
> > s/ls_pcie_host_init/Host init
> >
> > > + return ret;
> > > + }
> > > +
> > > + dw_pcie_setup_rc(&pci->pp);
> > > +
> >
> > Don't you need to configure iATU?
> >
> > > + ret = dw_pcie_wait_for_link(pci);
> >
> > Don't you need to start the link beforehand?
>
> Suppose need start link, it works at layerscape platform just because dwc
> have not full power off. some state still kept.
>
It may work for your platform but not for all if the power gets removed. So
please start the link manually.
- Mani
> >
> > > + if (ret) {
> > > + dev_err(pci->dev, "wait link up timeout! ret = 0x%x\n", ret);
> >
> > dw_pcie_wait_for_link() itself prints error message on failure. So no need to do
> > the same here.
>
> Okay
>
> >
> > - Mani
> >
> > > + return ret;
> > > + }
> > > +
> > > + return ret;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dw_pcie_resume_noirq);
> > > diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> > > index 79713ce075cc..effb07a506e4 100644
> > > --- a/drivers/pci/controller/dwc/pcie-designware.h
> > > +++ b/drivers/pci/controller/dwc/pcie-designware.h
> > > @@ -288,10 +288,21 @@ enum dw_pcie_core_rst {
> > > DW_PCIE_NUM_CORE_RSTS
> > > };
> > >
> > > +enum dw_pcie_ltssm {
> > > + DW_PCIE_LTSSM_UNKNOWN = 0xFFFFFFFF,
> > > + /* Need align PCIE_PORT_DEBUG0 bit0:5 */
> > > + DW_PCIE_LTSSM_DETECT_QUIET = 0x0,
> > > + DW_PCIE_LTSSM_DETECT_ACT = 0x1,
> > > + DW_PCIE_LTSSM_L0 = 0x11,
> > > + DW_PCIE_LTSSM_L2_IDLE = 0x15,
> > > +};
> > > +
> > > struct dw_pcie_host_ops {
> > > int (*host_init)(struct dw_pcie_rp *pp);
> > > void (*host_deinit)(struct dw_pcie_rp *pp);
> > > int (*msi_host_init)(struct dw_pcie_rp *pp);
> > > + void (*pme_turn_off)(struct dw_pcie_rp *pp);
> > > + void (*exit_from_l2)(struct dw_pcie_rp *pp);
> > > };
> > >
> > > struct dw_pcie_rp {
> > > @@ -364,6 +375,7 @@ struct dw_pcie_ops {
> > > void (*write_dbi2)(struct dw_pcie *pcie, void __iomem *base, u32 reg,
> > > size_t size, u32 val);
> > > int (*link_up)(struct dw_pcie *pcie);
> > > + enum dw_pcie_ltssm (*get_ltssm)(struct dw_pcie *pcie);
> > > int (*start_link)(struct dw_pcie *pcie);
> > > void (*stop_link)(struct dw_pcie *pcie);
> > > };
> > > @@ -393,6 +405,7 @@ struct dw_pcie {
> > > struct reset_control_bulk_data app_rsts[DW_PCIE_NUM_APP_RSTS];
> > > struct reset_control_bulk_data core_rsts[DW_PCIE_NUM_CORE_RSTS];
> > > struct gpio_desc *pe_rst;
> > > + bool suspended;
> > > };
> > >
> > > #define to_dw_pcie_from_pp(port) container_of((port), struct dw_pcie, pp)
> > > @@ -430,6 +443,9 @@ void dw_pcie_iatu_detect(struct dw_pcie *pci);
> > > int dw_pcie_edma_detect(struct dw_pcie *pci);
> > > void dw_pcie_edma_remove(struct dw_pcie *pci);
> > >
> > > +int dw_pcie_suspend_noirq(struct dw_pcie *pci);
> > > +int dw_pcie_resume_noirq(struct dw_pcie *pci);
> > > +
> > > static inline void dw_pcie_writel_dbi(struct dw_pcie *pci, u32 reg, u32 val)
> > > {
> > > dw_pcie_write_dbi(pci, reg, 0x4, val);
> > > @@ -501,6 +517,18 @@ static inline void dw_pcie_stop_link(struct dw_pcie *pci)
> > > pci->ops->stop_link(pci);
> > > }
> > >
> > > +static inline enum dw_pcie_ltssm dw_pcie_get_ltssm(struct dw_pcie *pci)
> > > +{
> > > + u32 val;
> > > +
> > > + if (pci->ops && pci->ops->get_ltssm)
> > > + return pci->ops->get_ltssm(pci);
> > > +
> > > + val = dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0);
> > > +
> > > + return (enum dw_pcie_ltssm)FIELD_GET(PORT_LOGIC_LTSSM_STATE_MASK, val);
> > > +}
> > > +
> > > #ifdef CONFIG_PCIE_DW_HOST
> > > irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp);
> > > int dw_pcie_setup_rc(struct dw_pcie_rp *pp);
> > > --
> > > 2.34.1
> > >
> >
> > --
> > மணிவண்ணன் சதாசிவம்
--
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