linux-kernel - Re: [PATCH v2 1/2] PCI: dwc: Perform host

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Date:   Tue, 24 Aug 2021 14:05:27 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Jingoo Han <jingoohan1@...il.com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Stanimir Varbanov <svarbanov@...sol.com>,
        linux-arm-msm@...r.kernel.org, linux-pci@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/2] PCI: dwc: Perform host_init() before registering
 msi

On Mon, Aug 23, 2021 at 08:49:57AM -0700, Bjorn Andersson wrote:
> On the Qualcomm sc8180x platform the bootloader does something related
> to PCI that leaves a pending "msi" interrupt, which with the current
> ordering often fires before init has a chance to enable the clocks that
> are necessary for the interrupt handler to access the hardware.
> 
> Move the host_init() call before the registration of the "msi" interrupt
> handler to ensure the host driver has a chance to enable the clocks.

Did you audit other drivers for similar issues?  If they do, we should
fix them all at once.

> The assignment of the bridge's ops and child_ops is moved along, because
> at least the TI Keystone driver overwrites these in its host_init
> callback.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
> 
> Changes since v1:
> - New patch, instead of enabling resources in the qcom driver before jumping to
>   dw_pcie_host_init(), per Rob Herring's suggestion.
> 
>  .../pci/controller/dwc/pcie-designware-host.c | 19 ++++++++++---------
>  1 file changed, 10 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index d1d9b8344ec9..f4755f3a03be 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -335,6 +335,16 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  	if (pci->link_gen < 1)
>  		pci->link_gen = of_pci_get_max_link_speed(np);
>  
> +	/* Set default bus ops */
> +	bridge->ops = &dw_pcie_ops;
> +	bridge->child_ops = &dw_child_pcie_ops;
> +
> +	if (pp->ops->host_init) {
> +		ret = pp->ops->host_init(pp);
> +		if (ret)
> +			return ret;
> +	}
> +
>  	if (pci_msi_enabled()) {
>  		pp->has_msi_ctrl = !(pp->ops->msi_host_init ||
>  				     of_property_read_bool(np, "msi-parent") ||
> @@ -388,15 +398,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  		}
>  	}
>  
> -	/* Set default bus ops */
> -	bridge->ops = &dw_pcie_ops;
> -	bridge->child_ops = &dw_child_pcie_ops;
> -
> -	if (pp->ops->host_init) {
> -		ret = pp->ops->host_init(pp);
> -		if (ret)
> -			goto err_free_msi;
> -	}
>  	dw_pcie_iatu_detect(pci);
>  
>  	dw_pcie_setup_rc(pp);
> -- 
> 2.29.2
>