Re: [PATCH] arm64: iort: take _DMA methods into account for named components

From: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
To: Ard Biesheuvel <ardb@kernel.org>
Cc: catalin.marinas@arm.com, will@kernel.org, robin.murphy@arm.com,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH] arm64: iort: take _DMA methods into account for named components
Date: Mon, 20 Apr 2020 09:40:51 +0100	[thread overview]
Message-ID: <20200420084051.GA12852@red-moon.cambridge.arm.com> (raw)
In-Reply-To: <20200404073047.17898-1-ardb@kernel.org>

On Sat, Apr 04, 2020 at 09:30:47AM +0200, Ard Biesheuvel wrote:
> Where IORT nodes for named components can describe simple DMA limits
> expressed as the number of address bits a device can driver, _DMA methods
> in AML can express more complex topologies, involving DMA translation in
> particular.
> 
> Currently, we only take this _DMA method into account if it appears on a
> ACPI device node describing a PCIe root complex, but it is perfectly
> acceptable to attach them to named components as well, so let's ensure
> we take them into account in those cases too.
> 
> Reported-by: Andrei Warkentin <awarkentin@vmware.com>
> Fixes: 7ad4263980826e8b ("ACPI: Make acpi_dma_configure() DMA regions aware")
> Cc: <stable@vger.kernel.org> # v4.14+
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
>  drivers/acpi/arm64/iort.c | 11 ++++-------
>  1 file changed, 4 insertions(+), 7 deletions(-)

Only question is whether there is FW in the field with _DMA methods that
now we would start parsing (and hopefully everything will still work)
but for that the only choice is applying this patch and see, so:

Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>

> diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> index ed3d2d1a7ae9..07eb78baf198 100644
> --- a/drivers/acpi/arm64/iort.c
> +++ b/drivers/acpi/arm64/iort.c
> @@ -1146,13 +1146,10 @@ void iort_dma_setup(struct device *dev, u64 *dma_addr, u64 *dma_size)
>  	else
>  		size = 1ULL << 32;
>  
> -	if (dev_is_pci(dev)) {
> -		ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> -		if (ret == -ENODEV)
> -			ret = rc_dma_get_range(dev, &size);
> -	} else {
> -		ret = nc_dma_get_range(dev, &size);
> -	}
> +	ret = acpi_dma_get_range(dev, &dmaaddr, &offset, &size);
> +	if (ret == -ENODEV)
> +		ret = dev_is_pci(dev) ? rc_dma_get_range(dev, &size)
> +				      : nc_dma_get_range(dev, &size);
>  
>  	if (!ret) {
>  		/*
> -- 
> 2.17.1
> 

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