[PATCH v12 10/13] usb: chipidea: add wait vbus lower than OTGSC_BSV before role starts

[Marc Kleine-Budde]

On 07/11/2013 08:27 AM, Peter Chen wrote:
> When the gadget role starts, we need to make sure the vbus is lower
> than OTGSC_BSV, or there will be an vbus interrupt since we use
> B_SESSION_VALID as vbus interrupt to indicate connect and disconnect.
> When the host role starts, it may not be useful to wait vbus to lower
> than OTGSC_BSV, but it can indicate some hardware problems like the
> vbus is still higher than OTGSC_BSV after we disconnect to host some
> time later (500 jiffies currently), which is obvious not correct.

Jiffies ist not constant. I think you have to specify the timeout in
fractions of HZ. The system ticks with HZ jiffies per second. So a
timeout of 500ms is "HZ / 2".

Marc

> 
> Signed-off-by: Peter Chen <peter.chen at freescale.com>
> ---
>  drivers/usb/chipidea/ci.h   |    3 +++
>  drivers/usb/chipidea/core.c |   32 ++++++++++++++++++++++++++++++++
>  drivers/usb/chipidea/otg.c  |    4 ++++
>  3 files changed, 39 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
> index 3160363..df27696 100644
> --- a/drivers/usb/chipidea/ci.h
> +++ b/drivers/usb/chipidea/ci.h
> @@ -308,4 +308,7 @@ int hw_port_test_set(struct ci_hdrc *ci, u8 mode);
>  
>  u8 hw_port_test_get(struct ci_hdrc *ci);
>  
> +int hw_wait_reg(struct ci_hdrc *ci, enum ci_hw_regs reg, u32 mask,
> +				u32 value, unsigned long timeout);
> +
>  #endif	/* __DRIVERS_USB_CHIPIDEA_CI_H */
> diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> index 7a07300..1c39541 100644
> --- a/drivers/usb/chipidea/core.c
> +++ b/drivers/usb/chipidea/core.c
> @@ -295,6 +295,38 @@ int hw_device_reset(struct ci_hdrc *ci, u32 mode)
>  	return 0;
>  }
>  
> +/**
> + * hw_wait_reg: wait the register value
> + *
> + * Sometimes, it needs to wait register value before going on.
> + * Eg, when switch to device mode, the vbus value should be lower
> + * than OTGSC_BSV before connects to host.
> + *
> + * @ci: the controller
> + * @reg: register index
> + * @mask: mast bit
> + * @value: the bit value to wait
> + * @timeout: timeout to indicate an error
                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Better: timeout in jiffies

> + *
> + * This function returns an error code if timeout
> + */
> +int hw_wait_reg(struct ci_hdrc *ci, enum ci_hw_regs reg, u32 mask,
> +				u32 value, unsigned long timeout)
> +{
> +	unsigned long elapse = jiffies + timeout;
> +
> +	while (hw_read(ci, reg, mask) != value) {
> +		if (time_after(jiffies, elapse)) {
> +			dev_err(ci->dev, "timeout waiting for %08x in %d\n",
> +					mask, reg);
> +			return -ETIMEDOUT;
> +		}
> +		msleep(20);
> +	}
> +
> +	return 0;
> +}
> +
>  static irqreturn_t ci_irq(int irq, void *data)
>  {
>  	struct ci_hdrc *ci = data;
> diff --git a/drivers/usb/chipidea/otg.c b/drivers/usb/chipidea/otg.c
> index c74194d..8aa0241 100644
> --- a/drivers/usb/chipidea/otg.c
> +++ b/drivers/usb/chipidea/otg.c
> @@ -67,6 +67,7 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
>  		usb_gadget_vbus_disconnect(&ci->gadget);
>  }
>  
> +#define CI_VBUS_STABLE_TIMEOUT 500
>  static void ci_handle_id_switch(struct ci_hdrc *ci)
>  {
>  	enum ci_role role = ci_otg_role(ci);
> @@ -76,6 +77,9 @@ static void ci_handle_id_switch(struct ci_hdrc *ci)
>  			ci_role(ci)->name, ci->roles[role]->name);
>  
>  		ci_role_stop(ci);
> +		/* wait vbus lower than OTGSC_BSV */
> +		hw_wait_reg(ci, OP_OTGSC, OTGSC_BSV, 0,
> +				CI_VBUS_STABLE_TIMEOUT);
>  		ci_role_start(ci, role);
>  	}
>  }
> 


-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |

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