linux-kernel - Re: [PATCH v2 05/13] PCI: endpoint: Assign PCI domain number for endpoint controllers

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Message-ID: <8b6cd895-8904-4d8c-bf23-5d933f476d57@linaro.org>
Date: Thu, 18 Jul 2024 14:11:00 +0200
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: manivannan.sadhasivam@...aro.org,
 Lorenzo Pieralisi <lpieralisi@...nel.org>,
 Krzysztof Wilczyński <kw@...ux.com>,
 Rob Herring <robh@...nel.org>, Bjorn Helgaas <bhelgaas@...gle.com>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Kishon Vijay Abraham I <kishon@...nel.org>,
 Bjorn Andersson <andersson@...nel.org>
Cc: linux-pci@...r.kernel.org, linux-arm-msm@...r.kernel.org,
 linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 05/13] PCI: endpoint: Assign PCI domain number for
 endpoint controllers

On 17.07.2024 7:03 PM, Manivannan Sadhasivam via B4 Relay wrote:
> From: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> 
> Right now, PCI endpoint subsystem doesn't assign PCI domain number for the
> PCI endpoint controllers. But this domain number could be useful to the EPC
> drivers to uniquely identify each controller based on the hardware instance
> when there are multiple ones present in an SoC (even multiple RC/EP).
> 
> So let's make use of the existing pci_bus_find_domain_nr() API to allocate
> domain numbers based on either Devicetree (linux,pci-domain) property or
> dynamic domain number allocation scheme.
> 
> It should be noted that the domain number allocated by this API will be
> based on both RC and EP controllers in a SoC. If the 'linux,pci-domain' DT
> property is present, then the domain number represents the actual hardware
> instance of the PCI endpoint controller. If not, then the domain number
> will be allocated based on the PCI EP/RC controller probe order.
> 
> If the architecture doesn't support CONFIG_PCI_DOMAINS_GENERIC (rare), then
> currently a warning is thrown to indicate that the architecture specific
> implementation is needed.
> 
> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> ---
>  drivers/pci/endpoint/pci-epc-core.c | 10 ++++++++++
>  include/linux/pci-epc.h             |  2 ++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/pci/endpoint/pci-epc-core.c b/drivers/pci/endpoint/pci-epc-core.c
> index 84309dfe0c68..7fa81b91e762 100644
> --- a/drivers/pci/endpoint/pci-epc-core.c
> +++ b/drivers/pci/endpoint/pci-epc-core.c
> @@ -838,6 +838,9 @@ void pci_epc_destroy(struct pci_epc *epc)
>  {
>  	pci_ep_cfs_remove_epc_group(epc->group);
>  	device_unregister(&epc->dev);
> +
> +	if (IS_ENABLED(CONFIG_PCI_DOMAINS_GENERIC))
> +		pci_bus_release_domain_nr(NULL, &epc->dev);	

Shouldn't this be called before device_unregister? pci/remove.c
does that (via pci_remove_bus() in pci_remove_root_bus())

Konrad