Re: [PATCH][RFC] PCI: rcar: Add bus notifier so we can limit the DMA range

[Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>]

On Tue, May 22, 2018 at 12:05:14AM +0200, Marek Vasut wrote:
> From: Phil Edworthy <phil.edworthy@renesas.com>
> 
> The PCIe DMA controller on RCar Gen2 and earlier is on 32bit bus,
> so limit the DMA range to 32bit.
> 
> Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Geert Uytterhoeven <geert+renesas@glider.be>
> Cc: Phil Edworthy <phil.edworthy@renesas.com>
> Cc: Simon Horman <horms+renesas@verge.net.au>
> Cc: Wolfram Sang <wsa@the-dreams.de>
> Cc: linux-renesas-soc@vger.kernel.org
> To: linux-pci@vger.kernel.org
> ---
> NOTE: I'm aware of https://patchwork.kernel.org/patch/9495895/ , but the
>       discussion seems to have gone way off, so I'm sending this as a
>       RFC. Any feedback on how to do this limiting properly would be nice.
> ---
>  drivers/pci/host/pcie-rcar.c | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)

The issue solved by this patch was solved in a more generic way through
this series:

https://lists.linuxfoundation.org/pipermail/iommu/2018-July/028792.html

I will therefore drop this patch from the PCI patch queue.

Thanks,
Lorenzo

> diff --git a/drivers/pci/host/pcie-rcar.c b/drivers/pci/host/pcie-rcar.c
> index c3eab0b95290..db2b16f40bc1 100644
> --- a/drivers/pci/host/pcie-rcar.c
> +++ b/drivers/pci/host/pcie-rcar.c
> @@ -1325,3 +1325,31 @@ static struct platform_driver rcar_pcie_driver = {
>  	.probe = rcar_pcie_probe,
>  };
>  builtin_platform_driver(rcar_pcie_driver);
> +
> +static int rcar_pcie_pci_notifier(struct notifier_block *nb,
> +			    unsigned long action, void *data)
> +{
> +	struct device *dev = data;
> +
> +	switch (action) {
> +	case BUS_NOTIFY_BOUND_DRIVER:
> +		/* Force the DMA mask to lower 32-bits */
> +		dma_set_mask_and_coherent(dev, DMA_BIT_MASK(32));
> +		break;
> +	default:
> +		return NOTIFY_DONE;
> +	}
> +
> +	return NOTIFY_OK;
> +}
> +
> +static struct notifier_block device_nb = {
> +	.notifier_call = rcar_pcie_pci_notifier,
> +};
> +
> +static int __init register_rcar_pcie_pci_notifier(void)
> +{
> +	return bus_register_notifier(&pci_bus_type, &device_nb);
> +}
> +
> +arch_initcall(register_rcar_pcie_pci_notifier);
> -- 
> 2.16.2
>