On Wed, Mar 11, 2015 at 01:42:42PM +0100, Bas Vermeulen wrote:
> i.MX35 has an issue that when USB DMA (SINGLE) transfers
> are interrupted, the usb core can hang.
>
> This patch implements the workaround described in ENGcm11601
> by setting the AHB to use INCR transfers instead of SINGLE
> transfers.
>
> Signed-off-by: Bas Vermeulen <bas.vermeulen@xxxxxxxxxxxx>
> CC: Sasha Hauer <kernel@xxxxxxxxxxxxxx>
> CC: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> ---
> drivers/usb/host/ehci-mxc.c | 17 +++++++++++++++++
> 1 file changed, 17 insertions(+)
>
> diff --git a/drivers/usb/host/ehci-mxc.c b/drivers/usb/host/ehci-mxc.c
> index c7a9b31..1a00492 100644
> --- a/drivers/usb/host/ehci-mxc.c
> +++ b/drivers/usb/host/ehci-mxc.c
> @@ -36,6 +36,7 @@
> static const char hcd_name[] = "ehci-mxc";
>
> #define ULPI_VIEWPORT_OFFSET 0x170
> +#define SBUSCFG_OFFSET 0x090
>
> struct ehci_mxc_priv {
> struct clk *usbclk, *ahbclk, *phyclk;
> @@ -43,8 +44,24 @@ struct ehci_mxc_priv {
>
> static struct hc_driver __read_mostly ehci_mxc_hc_driver;
>
> +static int ehci_mxc_reset(struct usb_hcd *hcd)
> +{
> + int retval;
> +
> + retval = ehci_setup(hcd);
> + if (retval)
> + return retval;
> +
> + /* workaround for ENGcm11601 */
> + if (of_machine_is_compatible("fsl,imx35"))
> + writel(0, hcd->regs + SBUSCFG_OFFSET);
This driver normally is not used with device tree. Without additional
kernel changes the chipidea driver is used instead.
Sascha
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