linux-kernel - Re: [PATCH 10/10] PCI: dwc: Do not write to MSI control registers if the platform doesn't use it

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Date:   Wed, 2 Jan 2019 10:13:03 +0000
From:   Gustavo Pimentel <gustavo.pimentel@...opsys.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Murali Karicheri <m-karicheri2@...com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Gustavo Pimentel <gustavo.pimentel@...opsys.com>,
        Marc Zyngier <marc.zyngier@....com>
CC:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Jingoo Han <jingoohan1@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10/10] PCI: dwc: Do not write to MSI control registers if
 the platform doesn't use it

Hi,

On 19/12/2018 12:42, Kishon Vijay Abraham I wrote:
> Platforms which populate msi_host_init, has it's own MSI controller
> logic. Writing to MSI control registers on platforms which doesn't use
> Designware's MSI controller logic might have side effects. To
> be safe, do not write to MSI control registers if the platform uses
> it's own MSI controller logic instead of Designware's MSI controller
> logic.
> 
> Signed-off-by: Kishon Vijay Abraham I <kishon@...com>
> ---
>  .../pci/controller/dwc/pcie-designware-host.c | 24 ++++++++++---------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
> index dbc94f3be3d5..6644a5683b2b 100644
> --- a/drivers/pci/controller/dwc/pcie-designware-host.c
> +++ b/drivers/pci/controller/dwc/pcie-designware-host.c
> @@ -647,17 +647,19 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
>  
>  	dw_pcie_setup(pci);
>  
> -	num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> -
> -	/* Initialize IRQ Status array */
> -	for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
> -		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK +
> -					(ctrl * MSI_REG_CTRL_BLOCK_SIZE),
> -				    4, ~0);
> -		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
> -					(ctrl * MSI_REG_CTRL_BLOCK_SIZE),
> -				    4, ~0);
> -		pp->irq_status[ctrl] = 0;
> +	if (!pp->ops->msi_host_init) {
> +		num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
> +
> +		/* Initialize IRQ Status array */
> +		for (ctrl = 0; ctrl < num_ctrls; ctrl++) {
> +			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_MASK +
> +					    (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
> +					    4, ~0);
> +			dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE +
> +					    (ctrl * MSI_REG_CTRL_BLOCK_SIZE),
> +					    4, ~0);
> +			pp->irq_status[ctrl] = 0;
> +		}
>  	}
>  
>  	/* Setup RC BARs */
> 

Acked-by: Gustavo Pimentel <gustavo.pimentel@...opsys.com>

Regards,
Gustavo