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Date: Wed, 27 Mar 2024 14:10:56 +0530
From: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
To: Niklas Cassel <cassel@kernel.org>
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Subject: Re: [PATCH v11 8/8] PCI: endpoint: Remove "core_init_notifier" flag
Message-ID: <20240327084056.GC2742@thinkpad>
References: <20240327-pci-dbi-rework-v11-0-6f5259f90673@linaro.org>
 <20240327-pci-dbi-rework-v11-8-6f5259f90673@linaro.org>
 <ZgPXpZgoMqVn8QHt@ryzen>
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On Wed, Mar 27, 2024 at 09:24:05AM +0100, Niklas Cassel wrote:
> Hello Mani,
> 
> On Wed, Mar 27, 2024 at 12:05:54PM +0530, Manivannan Sadhasivam wrote:
> > "core_init_notifier" flag is set by the glue drivers requiring refclk from
> > the host to complete the DWC core initialization. Also, those drivers will
> > send a notification to the EPF drivers once the initialization is fully
> > completed using the pci_epc_init_notify() API. Only then, the EPF drivers
> > will start functioning.
> > 
> > For the rest of the drivers generating refclk locally, EPF drivers will
> > start functioning post binding with them. EPF drivers rely on the
> > 'core_init_notifier' flag to differentiate between the drivers.
> > Unfortunately, this creates two different flows for the EPF drivers.
> > 
> > So to avoid that, let's get rid of the "core_init_notifier" flag and follow
> > a single initialization flow for the EPF drivers. This is done by calling
> > the dw_pcie_ep_init_notify() from all glue drivers after the completion of
> > dw_pcie_ep_init_registers() API. This will allow all the glue drivers to
> > send the notification to the EPF drivers once the initialization is fully
> > completed.
> > 
> > Only difference here is that, the drivers requiring refclk from host will
> > send the notification once refclk is received, while others will send it
> > during probe time itself.
> > 
> > But this also requires the EPC core driver to deliver the notification
> > after EPF driver bind. Because, the glue driver can send the notification
> > before the EPF drivers bind() and in those cases the EPF drivers will miss
> > the event. To accommodate this, EPC core is now caching the state of the
> > EPC initialization in 'init_complete' flag and pci-ep-cfs driver sends the
> > notification to EPF drivers based on that after each EPF driver bind.
> > 
> > Tested-by: Niklas Cassel <cassel@kernel.org>
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
> > ---
> >  drivers/pci/controller/cadence/pcie-cadence-ep.c  |  2 ++
> >  drivers/pci/controller/dwc/pci-dra7xx.c           |  2 ++
> >  drivers/pci/controller/dwc/pci-imx6.c             |  2 ++
> >  drivers/pci/controller/dwc/pci-keystone.c         |  2 ++
> >  drivers/pci/controller/dwc/pci-layerscape-ep.c    |  2 ++
> >  drivers/pci/controller/dwc/pcie-artpec6.c         |  2 ++
> >  drivers/pci/controller/dwc/pcie-designware-ep.c   |  1 +
> >  drivers/pci/controller/dwc/pcie-designware-plat.c |  2 ++
> >  drivers/pci/controller/dwc/pcie-keembay.c         |  2 ++
> >  drivers/pci/controller/dwc/pcie-qcom-ep.c         |  1 -
> >  drivers/pci/controller/dwc/pcie-rcar-gen4.c       |  2 ++
> >  drivers/pci/controller/dwc/pcie-tegra194.c        |  1 -
> >  drivers/pci/controller/dwc/pcie-uniphier-ep.c     |  2 ++
> >  drivers/pci/controller/pcie-rcar-ep.c             |  2 ++
> >  drivers/pci/controller/pcie-rockchip-ep.c         |  2 ++
> >  drivers/pci/endpoint/functions/pci-epf-test.c     | 18 +++++-------------
> >  drivers/pci/endpoint/pci-ep-cfs.c                 |  9 +++++++++
> >  drivers/pci/endpoint/pci-epc-core.c               | 22 ++++++++++++++++++++++
> >  include/linux/pci-epc.h                           |  7 ++++---
> >  19 files changed, 65 insertions(+), 18 deletions(-)
> > 
> > diff --git a/drivers/pci/controller/cadence/pcie-cadence-ep.c b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > index 2d0a8d78bffb..da67a06ee790 100644
> > --- a/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > +++ b/drivers/pci/controller/cadence/pcie-cadence-ep.c
> > @@ -734,6 +734,8 @@ int cdns_pcie_ep_setup(struct cdns_pcie_ep *ep)
> >  
> >  	spin_lock_init(&ep->lock);
> >  
> > +	dw_pcie_ep_init_notify(&pci->ep);
> 
> This looks wrong (and I think that you have not build tested this).
> 

Ah, this is silly. Sorry, added the change in a rush :(

> dw_* prefix indicates DWC, so it is a DWC specific function.
> 
> I don't think that you can use this function for the 3 non-DWC EPC drivers.
> I think that you need to use call pci_epc_init_notify() directly.
> 
> 
> (Also perhaps rebase your series on v6.9-rc1, I got conflicts when trying
> to apply it to v6.9-rc1, because it looks like the series is still based
> on v6.8-rc1.)
> 

I rebased the epf rework series and didn't get any conflict. But will rebase
this one also and send next version.

Thanks for noticing my idiocy.

- Mani

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