linux-kernel - Re: [PATCH v3 04/22] usb: chipidea: Only read/write OTGSC from one place

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Date:   Fri, 2 Sep 2016 10:43:37 +0800
From:   Peter Chen <hzpeterchen@...il.com>
To:     Stephen Boyd <stephen.boyd@...aro.org>
Cc:     linux-usb@...r.kernel.org, Felipe Balbi <balbi@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        Neil Armstrong <narmstrong@...libre.com>,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Peter Chen <peter.chen@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Andy Gross <andy.gross@...aro.org>,
        "Ivan T. Ivanov" <iivanov.xz@...il.com>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 04/22] usb: chipidea: Only read/write OTGSC from one
 place

On Wed, Aug 31, 2016 at 05:40:18PM -0700, Stephen Boyd wrote:
> With the id and vbus detection done via extcon we need to make
> sure we poll the status of OTGSC properly by considering what the
> extcon is saying, and not just what the register is saying. Let's
> move this hw_wait_reg() function to the only place it's used and
> simplify it for polling the OTGSC register. Then we can make
> certain we only use the hw_read_otgsc() API to read OTGSC, which
> will make sure we properly handle extcon events.
> 
> Cc: Peter Chen <peter.chen@....com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Ivan T. Ivanov" <iivanov.xz@...il.com>
> Fixes: 3ecb3e09b042 ("usb: chipidea: Use extcon framework for VBUS and ID detect")
> Signed-off-by: Stephen Boyd <stephen.boyd@...aro.org>
> ---
>  drivers/usb/chipidea/ci.h   |  3 ---
>  drivers/usb/chipidea/core.c | 32 --------------------------------
>  drivers/usb/chipidea/otg.c  | 34 ++++++++++++++++++++++++++++++----
>  3 files changed, 30 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
> index cd414559040f..05bc4d631cb9 100644
> --- a/drivers/usb/chipidea/ci.h
> +++ b/drivers/usb/chipidea/ci.h
> @@ -428,9 +428,6 @@ 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 int timeout_ms);
> -
>  void ci_platform_configure(struct ci_hdrc *ci);
>  
>  int dbg_create_files(struct ci_hdrc *ci);
> diff --git a/drivers/usb/chipidea/core.c b/drivers/usb/chipidea/core.c
> index 69426e644d17..01390e02ee53 100644
> --- a/drivers/usb/chipidea/core.c
> +++ b/drivers/usb/chipidea/core.c
> @@ -516,38 +516,6 @@ int hw_device_reset(struct ci_hdrc *ci)
>  	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_ms: timeout in millisecond
> - *
> - * 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 int timeout_ms)
> -{
> -	unsigned long elapse = jiffies + msecs_to_jiffies(timeout_ms);
> -
> -	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 03b6743461d1..a829607c3e4d 100644
> --- a/drivers/usb/chipidea/otg.c
> +++ b/drivers/usb/chipidea/otg.c
> @@ -104,7 +104,31 @@ void ci_handle_vbus_change(struct ci_hdrc *ci)
>  		usb_gadget_vbus_disconnect(&ci->gadget);
>  }
>  
> -#define CI_VBUS_STABLE_TIMEOUT_MS 5000
> +/**
> + * When we switch to device mode, the vbus value should be lower
> + * than OTGSC_BSV before connecting to host.
> + *
> + * @ci: the controller
> + *
> + * This function returns an error code if timeout
> + */
> +static int hw_wait_vbus_lower_bsv(struct ci_hdrc *ci)
> +{
> +	unsigned long elapse = jiffies + msecs_to_jiffies(5000);
> +	u32 mask = OTGSC_BSV;
> +
> +	while (hw_read_otgsc(ci, mask)) {
> +		if (time_after(jiffies, elapse)) {
> +			dev_err(ci->dev, "timeout waiting for %08x in OTGSC\n",
> +					mask);
> +			return -ETIMEDOUT;
> +		}
> +		msleep(20);
> +	}
> +
> +	return 0;
> +}
> +
>  static void ci_handle_id_switch(struct ci_hdrc *ci)
>  {
>  	enum ci_role role = ci_otg_role(ci);
> @@ -116,9 +140,11 @@ static void ci_handle_id_switch(struct ci_hdrc *ci)
>  		ci_role_stop(ci);
>  
>  		if (role == CI_ROLE_GADGET)
> -			/* wait vbus lower than OTGSC_BSV */
> -			hw_wait_reg(ci, OP_OTGSC, OTGSC_BSV, 0,
> -					CI_VBUS_STABLE_TIMEOUT_MS);
> +			/*
> +			 * wait vbus lower than OTGSC_BSV before connecting
> +			 * to host
> +			 */
> +			hw_wait_vbus_lower_bsv(ci);
>  
>  		ci_role_start(ci, role);
>  	}

Acked-by: Peter Chen <peter.chen@....com>

-- 

Best Regards,
Peter Chen