[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20160715094542.GE1041@n2100.armlinux.org.uk>
Date: Fri, 15 Jul 2016 10:45:42 +0100
From: Russell King - ARM Linux <linux@...linux.org.uk>
To: Anup Patel <anup.patel@...adcom.com>
Cc: "Hans J. Koch" <hjk@...sjkoch.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jonathan Corbet <corbet@....net>,
Scott Branden <sbranden@...adcom.com>,
linux-doc@...r.kernel.org, Ray Jui <rjui@...adcom.com>,
linux-kernel@...r.kernel.org, Rob Herring <robh+dt@...nel.org>,
bcm-kernel-feedback-list@...adcom.com,
Ankit Jindal <thatsjindal@...il.com>,
linux-arm-kernel@...ts.infradead.org,
Jan Viktorin <viktorin@...ivetech.com>
Subject: Re: [PATCH 7/8] uio: bind uio_dmem_genirq via OF
On Fri, Jul 15, 2016 at 02:34:02PM +0530, Anup Patel wrote:
> +static int uio_dmem_genirq_alloc_platdata(struct platform_device *pdev)
> +{
> + struct uio_dmem_genirq_pdata pdata;
> + u32 dma_bits, regions;
> + u32 sizes[MAX_UIO_MAPS];
> + int ret;
> +
> + memset(&pdata, 0, sizeof(pdata));
> +
> + ret = of_property_read_u32(pdev->dev.of_node,
> + uio_of_dma_bits_prop, &dma_bits);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "Missing property %s\n", uio_of_dma_bits_prop);
> + return ret;
> + }
> + if (dma_bits > 64)
> + dma_bits = 64;
> +
> + dma_set_coherent_mask(&pdev->dev, DMA_BIT_MASK(dma_bits));
You really need to check the return value from this: this function
negotiates with the architecture, and if 64-bit DMA is not supported,
then the call will fail and you as a driver are expected to fall back
to 32-bit DMA only.
In that case, you're expected to call the same function with a 32-bit
mask, and if that fails, you're supposed to then decide that DMA is
not possible.
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up
according to speedtest.net.
Powered by blists - more mailing lists