On 4/20/2016 2:31 PM, dingu...@opensource.altera.com wrote:
> From: Dinh Nguyen <dingu...@opensource.altera.com>
>
> Allow for platforms that have a reset controller driver in place to bring
> the USB IP out of reset.
>
> Signed-off-by: Dinh Nguyen <dingu...@opensource.altera.com>
> ---
> v6: fix 80 line checkpatch warning in dev_err print
> v5: updated error conditions for not finding the reset property
> v4: use dev_dbg() if not a -EPROBE_DEFER
> v3: fix compile error
> v2: move to lowlevel_hw_init()
> ---
> drivers/usb/dwc2/core.h | 1 +
> drivers/usb/dwc2/platform.c | 21 +++++++++++++++++++++
> 2 files changed, 22 insertions(+)
>
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 3c58d63..f748132 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -837,6 +837,7 @@ struct dwc2_hsotg {
> void *priv;
> int irq;
> struct clk *clk;
> + struct reset_control *reset;
>
> unsigned int queuing_high_bandwidth:1;
> unsigned int srp_success:1;
> diff --git a/drivers/usb/dwc2/platform.c b/drivers/usb/dwc2/platform.c
> index 88629be..fa2c097 100644
> --- a/drivers/usb/dwc2/platform.c
> +++ b/drivers/usb/dwc2/platform.c
> @@ -45,6 +45,7 @@
> #include <linux/platform_device.h>
> #include <linux/phy/phy.h>
> #include <linux/platform_data/s3c-hsotg.h>
> +#include <linux/reset.h>
>
> #include <linux/usb/of.h>
>
> @@ -337,6 +338,23 @@ static int dwc2_lowlevel_hw_init(struct dwc2_hsotg
> *hsotg)
> {
> int i, ret;
>
> + hsotg->reset = devm_reset_control_get(hsotg->dev, "dwc2");
> + if (IS_ERR(hsotg->reset)) {
> + ret = PTR_ERR(hsotg->reset);
> + switch (ret) {
> + case -ENOENT:
> + hsotg->reset = NULL;
> + break;
> + default:
> + dev_err(hsotg->dev, "error getting reset control %d\n",
> + ret);
> + return ret;
> + }
> + }
> +
> + if (hsotg->reset)
> + reset_control_deassert(hsotg->reset);
> +
> /* Set default UTMI width */
> hsotg->phyif = GUSBCFG_PHYIF16;
>
> @@ -434,6 +452,9 @@ static int dwc2_driver_remove(struct platform_device *dev)
> if (hsotg->ll_hw_enabled)
> dwc2_lowlevel_hw_disable(hsotg);
>
> + if (hsotg->reset)
> + reset_control_assert(hsotg->reset);
> +
> return 0;
> }
>
>
Hi Dinh,
On my system, with no reset controller configured, this fails
devm_reset_control_get() with -EINVAL, and it also spits out a
backtrace.
Hi Philipp,
I think devm_reset_control_get() should return either NULL or some
other error to indicate that the reset controller is not
configured. That way we can check it and handle that condition. If we
check for -EINVAL, we might miss a legitimate error that is returning
-EINVAL.
Also I think the WARN_ON(1) should be removed for this case.
Any thoughts on this or other suggestions to resolve it?
Regards,
John
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