Re: [PATCH 06/11] PCI: endpoint: Introduce EPC 'deinit' event and notify the EPF drivers

Manivannan Sadhasivam
2024-03-26T08:31:26Z

On Fri, Mar 22, 2024 at 05:10:17PM +0100, Niklas Cassel wrote:
> On Thu, Mar 14, 2024 at 08:53:45PM +0530, Manivannan Sadhasivam wrote:
> > As like the EPC 'init' event, that is used to signal the EPF drivers about
> > the EPC initialization, let's introduce 'deinit' event that is used to
> > signal EPC deinitialization.
> >
> > The EPC deinitialization applies only when any sort of fundamental reset
> > is supported by the endpoint controller as per the PCIe spec.
> >
> > Reference: PCIe Base spec v5.0, sections 4.2.4.9.1 and 6.6.1.
> >
> > Currently, some EPC drivers like pcie-qcom-ep and pcie-tegra194 support
> > PERST# as the fundamental reset. So the 'deinit' event will be notified to
> > the EPF drivers when PERST# assert happens in the above mentioned EPC
> > drivers.
> >
> > The EPF drivers, on receiving the event through the deinit() callback
> > should reset the EPF state machine and also cleanup any configuration that
> > got affected by the fundamental reset like BAR, DMA etc...
> >
> > This change also warrants skipping the cleanups in unbind() if already done
> > in deinit().
> >
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> > drivers/pci/controller/dwc/pcie-qcom-ep.c | 1 +
> > drivers/pci/controller/dwc/pcie-tegra194.c | 1 +
> > drivers/pci/endpoint/functions/pci-epf-mhi.c | 19 +++++++++++++++++++
> > drivers/pci/endpoint/functions/pci-epf-test.c | 17 +++++++++++++++--
> > drivers/pci/endpoint/pci-epc-core.c | 25 +++++++++++++++++++++++++
> > include/linux/pci-epc.h | 1 +
> > include/linux/pci-epf.h | 2 ++
> > 7 files changed, 64 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-qcom-ep.c b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > index 50b1635e3cbb..e4b742355d57 100644
> > --- a/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > +++ b/drivers/pci/controller/dwc/pcie-qcom-ep.c
> > @@ -501,6 +501,7 @@ static void qcom_pcie_perst_assert(struct dw_pcie *pci)
> > {
> > struct qcom_pcie_ep *pcie_ep = to_pcie_ep(pci);
> >
> > + pci_epc_deinit_notify(pci->ep.epc);
>
> Why not just move pci_epc_deinit_notify() in to dw_pcie_ep_cleanup() ?
> (So that we don't need to add pci_epc_deinit_notify() to all EPC drivers
> with PERST?)
>

This is mostly done to keep similarity with dw_pcie_ep_init_notify(). Even
though it is a helper, it explicitly says that the function sends init
notification. Otherwise, it will confuse developers on who is calling the
deinit_notify(). I believe there is already enough mess to confuse the
newcomers ;)

- Mani

> Regardless:
> Reviewed-by: Niklas Cassel <cassel@kernel.org>
>
> > dw_pcie_ep_cleanup(&pci->ep);
> > qcom_pcie_disable_resources(pcie_ep);
> > pcie_ep->link_status = QCOM_PCIE_EP_LINK_DISABLED;
> > diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> > index e02deb31a72d..3e6e08b321fb 100644
> > --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> > +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> > @@ -1715,6 +1715,7 @@ static void pex_ep_event_pex_rst_assert(struct tegra_pcie_dw *pcie)
> > if (ret)
> > dev_err(pcie->dev, "Failed to go Detect state: %d\n", ret);
> >
> > + pci_epc_deinit_notify(pcie->pci.ep.epc);
> > dw_pcie_ep_cleanup(&pcie->pci.ep);
> >
> > reset_control_assert(pcie->core_rst);
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-mhi.c b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > index 4e4300efd9d7..83de96119718 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-mhi.c
> > @@ -748,6 +748,24 @@ static int pci_epf_mhi_epc_init(struct pci_epf *epf)
> > return 0;
> > }
> >
> > +static void pci_epf_mhi_epc_deinit(struct pci_epf *epf)
> > +{
> > + struct pci_epf_mhi *epf_mhi = epf_get_drvdata(epf);
> > + const struct pci_epf_mhi_ep_info *info = epf_mhi->info;
> > + struct pci_epf_bar *epf_bar = &epf->bar[info->bar_num];
> > + struct mhi_ep_cntrl *mhi_cntrl = &epf_mhi->mhi_cntrl;
> > + struct pci_epc *epc = epf->epc;
> > +
> > + if (mhi_cntrl->mhi_dev) {
> > + mhi_ep_power_down(mhi_cntrl);
> > + if (info->flags & MHI_EPF_USE_DMA)
> > + pci_epf_mhi_dma_deinit(epf_mhi);
> > + mhi_ep_unregister_controller(mhi_cntrl);
> > + }
> > +
> > + pci_epc_clear_bar(epc, epf->func_no, epf->vfunc_no, epf_bar);
> > +}
> > +
> > static int pci_epf_mhi_link_up(struct pci_epf *epf)
> > {
> > struct pci_epf_mhi *epf_mhi = epf_get_drvdata(epf);
> > @@ -882,6 +900,7 @@ static void pci_epf_mhi_unbind(struct pci_epf *epf)
> >
> > static const struct pci_epc_event_ops pci_epf_mhi_epc_event_ops = {
> > .init = pci_epf_mhi_epc_init,
> > + .deinit = pci_epf_mhi_epc_deinit,
> > };
> >
> > static const struct pci_epc_bus_event_ops pci_epf_mhi_bus_event_ops = {
> > diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> > index 8f1e0cb08814..84cd47ebac22 100644
> > --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> > +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> > @@ -804,6 +804,15 @@ static int pci_epf_test_epc_init(struct pci_epf *epf)
> > return 0;
> > }
> >
> > +static void pci_epf_test_epc_deinit(struct pci_epf *epf)
> > +{
> > + struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> > +
> > + cancel_delayed_work(&epf_test->cmd_handler);
> > + pci_epf_test_clean_dma_chan(epf_test);
> > + pci_epf_test_clear_bar(epf);
> > +}
> > +
> > static int pci_epf_test_link_up(struct pci_epf *epf)
> > {
> > struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> > @@ -816,6 +825,7 @@ static int pci_epf_test_link_up(struct pci_epf *epf)
> >
> > static const struct pci_epc_event_ops pci_epf_test_epc_event_ops = {
> > .init = pci_epf_test_epc_init,
> > + .deinit = pci_epf_test_epc_deinit,
> > };
> >
> > static const struct pci_epc_bus_event_ops pci_epf_test_bus_event_ops = {
> > @@ -954,10 +964,13 @@ static int pci_epf_test_bind(struct pci_epf *epf)
> > static void pci_epf_test_unbind(struct pci_epf *epf)
> > {
> > struct pci_epf_test *epf_test = epf_get_drvdata(epf);
> > + struct pci_epc *epc = epf->epc;
> >
> > cancel_delayed_work(&epf_test->cmd_handler);
> > - pci_epf_test_clean_dma_chan(epf_test);
> > - pci_epf_test_clear_bar(epf);
> > + if (epc->init_complete) {
> > + pci_epf_test_clean_dma_chan(epf_test);
> > + pci_epf_test_clear_bar(epf);
> > + }
> > pci_epf_test_free_space(epf);
> > }
> >
> > diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> > index 5a522b2842e2..26378a9a56a7 100644
> > --- a/drivers/pci/endpoint/pci-epc-core.c
> > +++ b/drivers/pci/endpoint/pci-epc-core.c
> > @@ -779,6 +779,31 @@ void pci_epc_notify_pending_init(struct pci_epc *epc, struct pci_epf *epf)
> > }
> > EXPORT_SYMBOL_GPL(pci_epc_notify_pending_init);
> >
> > +/**
> > + * pci_epc_deinit_notify() - Notify the EPF device about EPC deinitialization
> > + * @epc: the EPC device whose deinitialization is completed
> > + *
> > + * Invoke to notify the EPF device that the EPC deinitialization is completed.
> > + */
> > +void pci_epc_deinit_notify(struct pci_epc *epc)
> > +{
> > + struct pci_epf *epf;
> > +
> > + if (IS_ERR_OR_NULL(epc))
> > + return;
> > +
> > + mutex_lock(&epc->list_lock);
> > + list_for_each_entry(epf, &epc->pci_epf, list) {
> > + mutex_lock(&epf->lock);
> > + if (epf->epc_event_ops && epf->epc_event_ops->deinit)
> > + epf->epc_event_ops->deinit(epf);
> > + mutex_unlock(&epf->lock);
> > + }
> > + epc->init_complete = false;
> > + mutex_unlock(&epc->list_lock);
> > +}
> > +EXPORT_SYMBOL_GPL(pci_epc_deinit_notify);
> > +
> > /**
> > * pci_epc_bme_notify() - Notify the EPF device that the EPC device has received
> > * the BME event from the Root complex
> > diff --git a/include/linux/pci-epc.h b/include/linux/pci-epc.h
> > index adee6dbe4e45..976b2212e872 100644
> > --- a/include/linux/pci-epc.h
> > +++ b/include/linux/pci-epc.h
> > @@ -199,6 +199,7 @@ void pci_epc_linkup(struct pci_epc *epc);
> > void pci_epc_linkdown(struct pci_epc *epc);
> > void pci_epc_init_notify(struct pci_epc *epc);
> > void pci_epc_notify_pending_init(struct pci_epc *epc, struct pci_epf *epf);
> > +void pci_epc_deinit_notify(struct pci_epc *epc);
> > void pci_epc_bme_notify(struct pci_epc *epc);
> > void pci_epc_remove_epf(struct pci_epc *epc, struct pci_epf *epf,
> > enum pci_epc_interface_type type);
> > diff --git a/include/linux/pci-epf.h b/include/linux/pci-epf.h
> > index ff8304e72f8e..52f69eaf505d 100644
> > --- a/include/linux/pci-epf.h
> > +++ b/include/linux/pci-epf.h
> > @@ -70,9 +70,11 @@ struct pci_epf_ops {
> > /**
> > * struct pci_epc_event_ops - Callbacks for capturing the EPC specific events
> > * @init: Callback for the EPC initialization event
> > + * @deinit: Callback for the EPC deinitialization event
> > */
> > struct pci_epc_event_ops {
> > int (*init)(struct pci_epf *epf);
> > + void (*deinit)(struct pci_epf *epf);
> > };
> >
> > /**
> >
> > --
> > 2.25.1
> >

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