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From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Jingoo Han <jingoohan1@gmail.com>,
	Gustavo Pimentel <gustavo.pimentel@synopsys.com>,
	Bjorn Helgaas <bhelgaas@google.com>,
	linux-pci@vger.kernel.org, Tim Harvey <tharvey@gateworks.com>,
	kernel@pengutronix.de, patchwork-lst@pengutronix.de
Subject: Re: [PATCH] PCI: dwc: skip MSI init if MSIs have been explicitly disabled
Date: Fri, 1 Mar 2019 12:29:02 +0000
Message-ID: <20190301121119.GA21064@e107981-ln.cambridge.arm.com> (raw)
In-Reply-To: <20190227165219.31911-1-l.stach@pengutronix.de>

On Wed, Feb 27, 2019 at 05:52:19PM +0100, Lucas Stach wrote:
> Since 7c5925afbc58 (PCI: dwc: Move MSI IRQs allocation to IRQ domains
> hierarchical API) the MSI init claims one of the controller IRQs as a
> chained IRQ line for the MSI controller. On some designs, like the i.MX6,
> this line is shared with a PCIe legacy IRQ. When the line is claimed for
> the MSI domain, any device trying to use this legacy IRQs will fail to
> request this IRQ line.
> 
> As MSI and legacy IRQs are already mutually exclusive on the DWC core,
> as the core won't forward any legacy IRQs once any MSI has been enabled,
> users wishing to use legacy IRQs already need to explictly disable MSI
> support (usually via the pci=nomsi kernel commandline option). To avoid
> any issues with MSI conflicting with legacy IRQs, just skip all of the
> DWC MSI initalization, including the IRQ line claim, when MSI is disabled.
> 
> Fixes: c5925afbc58
>        (PCI: dwc: Move MSI IRQs allocation to IRQ domains hierarchical API)
> Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
> Tested-by: Tim Harvey <tharvey@gateworks.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware-host.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied to pci/dwc for v5.1, added CC: stable too as requested.

Lorenzo

> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index 29a05759a294..f4a8494f616b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -433,7 +433,7 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  	if (ret)
>  		pci->num_viewport = 2;
>  
> -	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> +	if (IS_ENABLED(CONFIG_PCI_MSI) && pci_msi_enabled()) {
>  		/*
>  		 * If a specific SoC driver needs to change the
>  		 * default number of vectors, it needs to implement
> -- 
> 2.20.1
> 

  parent reply index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-27 16:52 Lucas Stach
2019-02-27 17:25 ` Fabio Estevam
2019-02-27 17:43   ` Tim Harvey
2019-02-28 13:29 ` Lorenzo Pieralisi
2019-03-01 10:10   ` Gustavo Pimentel
2019-03-01 12:29 ` Lorenzo Pieralisi [this message]
2019-03-04 19:25 ` Bjorn Helgaas
2019-03-04 19:39   ` Lucas Stach
2019-03-04 20:18     ` Marc Zyngier
2019-03-06  9:53       ` Gustavo Pimentel
2019-03-06 11:39         ` Lucas Stach
2019-03-06 15:59       ` Tim Harvey
2019-04-15 14:34       ` Gustavo Pimentel

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