Re: [PATCH 1/4] usb: musb: Implement session bit based runtime PM for musb-core

[Bin Liu <b-liu-l0cyMroinI0@public.gmane.org>]

On Thu, Aug 18, 2016 at 03:46:47PM -0700, Tony Lindgren wrote:
> We want to keep musb enabled always when the session bit is
> set. This simplifies the PM runtime and allows making it more
> generic across the various glue layers.
> 
> So far the only exception to just following the session bit is
> host mode disconnect where the session bit stays set.
> 
> In that case, just allow PM and let the PM runtime autoidle
> timeout deal with it.
> 
> Signed-off-by: Tony Lindgren <tony-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
> ---
>  drivers/usb/musb/musb_core.c | 70 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/usb/musb/musb_core.h |  1 +
>  2 files changed, 71 insertions(+)
> 
> diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c
> index 74fc306..9c4e1a5 100644
> --- a/drivers/usb/musb/musb_core.c
> +++ b/drivers/usb/musb/musb_core.c
> @@ -1831,11 +1831,81 @@ static const struct attribute_group musb_attr_group = {
>  	.attrs = musb_attributes,
>  };
>  
> +#define MUSB_QUIRK_B_INVALID_VBUS_91	(MUSB_DEVCTL_BDEVICE | \
> +					 (2 << MUSB_DEVCTL_VBUS_SHIFT) | \
> +					 MUSB_DEVCTL_SESSION)
> +#define MUSB_QUIRK_A_DISCONNECT_19	((3 << MUSB_DEVCTL_VBUS_SHIFT) | \
> +					 MUSB_DEVCTL_SESSION)
> +
> +/*
> + * Check the musb devctl session bit to determine if we want to
> + * allow PM runtime for the device. In general, we want to keep things
> + * active when the session bit is set except after host disconnect.
> + *
> + * Only called from musb_irq_work. If this ever needs to get called
> + * elsewhere, proper locking must be implemented for musb->session.
> + */
> +static void musb_pm_runtime_check_session(struct musb *musb)
> +{
> +	u8 devctl, s;
> +	int error;
> +
> +	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
> +
> +	/* Handle session status quirks first */
> +	s = MUSB_DEVCTL_FSDEV | MUSB_DEVCTL_LSDEV |
> +		MUSB_DEVCTL_HR;
> +	switch (devctl & ~s) {
> +	case MUSB_QUIRK_B_INVALID_VBUS_91:
> +		if (musb->session)
> +			break;
> +		dev_dbg(musb->controller,
> +			"Allow PM as device with invalid vbus: %02x\n",
> +			devctl);
> +		return;
> +	case MUSB_QUIRK_A_DISCONNECT_19:
> +		if (!musb->session)
> +			break;
> +		dev_dbg(musb->controller,
> +			"Allow PM on possible host mode disconnect\n");
> +		pm_runtime_mark_last_busy(musb->controller);
> +		pm_runtime_put_autosuspend(musb->controller);
> +		musb->session = false;
> +		return;
> +	default:
> +		break;
> +	}
> +
> +	/* No need to do anything if session has not changed */
> +	s = devctl & MUSB_DEVCTL_SESSION;
> +	if (s == musb->session)
> +		return;
> +
> +	/* Block PM or allow PM? */
> +	if (s) {
> +		dev_dbg(musb->controller, "Block PM on active session: %02x\n",
> +			devctl);
> +		error = pm_runtime_get_sync(musb->controller);
> +		if (error < 0)
> +			dev_err(musb->controller, "Could not enable: %i\n",
> +				error);
> +	} else {
> +		dev_dbg(musb->controller, "Allow PM with no session: %02x\n",
> +			devctl);

I changed dev_dbg() to musb_dbg(). musb core already moves to
tracepoints for debug.

> +		pm_runtime_mark_last_busy(musb->controller);
> +		pm_runtime_put_autosuspend(musb->controller);
> +	}
> +
> +	musb->session = s;
> +}
> +
>  /* Only used to provide driver mode change events */
>  static void musb_irq_work(struct work_struct *data)
>  {
>  	struct musb *musb = container_of(data, struct musb, irq_work);
>  
> +	musb_pm_runtime_check_session(musb);
> +
>  	if (musb->xceiv->otg->state != musb->xceiv_old_state) {
>  		musb->xceiv_old_state = musb->xceiv->otg->state;
>  		sysfs_notify(&musb->controller->kobj, NULL, "mode");
> diff --git a/drivers/usb/musb/musb_core.h b/drivers/usb/musb/musb_core.h
> index b55a776..65288a5 100644
> --- a/drivers/usb/musb/musb_core.h
> +++ b/drivers/usb/musb/musb_core.h
> @@ -378,6 +378,7 @@ struct musb {
>  	u8			min_power;	/* vbus for periph, in mA/2 */
>  
>  	int			port_mode;	/* MUSB_PORT_MODE_* */
> +	bool			session;
>  	bool			is_host;
>  
>  	int			a_wait_bcon;	/* VBUS timeout in msecs */
> -- 
> 2.8.1
> 
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