linux-kernel - Re: [PATCH] PCI: endpoint: Don't stop EP controller by EP function

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Date:   Tue, 5 Jul 2022 17:40:28 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Shunsuke Mie <mie@...l.co.jp>
Cc:     Kishon Vijay Abraham I <kishon@...com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Hou Zhiqiang <Zhiqiang.Hou@....com>,
        Li Chen <lchen@...arella.com>, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] PCI: endpoint: Don't stop EP controller by EP function

On Wed, Jun 22, 2022 at 01:09:24PM +0900, Shunsuke Mie wrote:
> For multi-function endpoint device, an ep function shouldn't stop EP
> controller. Nomally the controller is stopped via configfs.

Can you please clarify this for me?

An endpoint function by itself wouldn't stop an endpoint controller.

I assume that some *operation* on an endpoint function currently stops
the endpoint controller, but that operation should not stop the
controller?

I guess the operation is an "unbind" that detaches an EPF device from
an EPC device?

> Fixes: 349e7a85b25f ("PCI: endpoint: functions: Add an EP function to test PCI")
> Signed-off-by: Shunsuke Mie <mie@...l.co.jp>
> ---
>  drivers/pci/endpoint/functions/pci-epf-test.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/drivers/pci/endpoint/functions/pci-epf-test.c b/drivers/pci/endpoint/functions/pci-epf-test.c
> index 5b833f00e980..a5ed779b0a51 100644
> --- a/drivers/pci/endpoint/functions/pci-epf-test.c
> +++ b/drivers/pci/endpoint/functions/pci-epf-test.c
> @@ -627,7 +627,6 @@ static void pci_epf_test_unbind(struct pci_epf *epf)
>  
>  	cancel_delayed_work(&epf_test->cmd_handler);
>  	pci_epf_test_clean_dma_chan(epf_test);
> -	pci_epc_stop(epc);
>  	for (bar = 0; bar < PCI_STD_NUM_BARS; bar++) {
>  		epf_bar = &epf->bar[bar];
>  
> -- 
> 2.17.1
>