linux-kernel - Re: [PATCH v3 6/8] usb: dwc2: host: Assume all devices are on one single

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Date:	Thu, 19 Nov 2015 09:34:11 -0600
From:	Felipe Balbi <balbi@...com>
To:	Douglas Anderson <dianders@...omium.org>,
	John Youn <John.Youn@...opsys.com>
CC:	Yunzhi Li <lyz@...k-chips.com>,
	Heiko Stübner <heiko@...ech.de>,
	<linux-rockchip@...ts.infradead.org>,
	Julius Werner <jwerner@...omium.org>,
	<gregory.herrero@...el.com>, <yousaf.kaukab@...el.com>,
	<dinguyen@...nsource.altera.com>, <stern@...land.harvard.edu>,
	<ming.lei@...onical.com>, Douglas Anderson <dianders@...omium.org>,
	<johnyoun@...opsys.com>, <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 6/8] usb: dwc2: host: Assume all devices are on one single_tt hub


Hi,

Douglas Anderson <dianders@...omium.org> writes:
> Until we have logic to determine which devices share the same TT let's
> add logic to assume that all devices on a given dwc2 controller are on
> one single_tt hub.  This is better than the previous code that assumed
> that all devices were on one multi_tt hub, since single_tt hubs
> appear (in my experience) to be much more common and any schedule that
> would work on a single_tt hub will also work on a multi_tt hub.  This
> will prevent more than 8 total low/full speed devices to be on the bus
> at one time, but that's a reasonable restriction until we've made things
> smarter.
>
> Signed-off-by: Douglas Anderson <dianders@...omium.org>
> ---
> Changes in v3:
> - Assuming single_tt is new for v3; not terribly well tested (yet).
>
> Changes in v2: None
>
>  drivers/usb/dwc2/core.h      |  1 +
>  drivers/usb/dwc2/hcd_queue.c | 40 +++++++++++++++++++++++++++++++++++++++-
>  2 files changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/usb/dwc2/core.h b/drivers/usb/dwc2/core.h
> index 567ee2c9e69f..09aa2b5ae29e 100644
> --- a/drivers/usb/dwc2/core.h
> +++ b/drivers/usb/dwc2/core.h
> @@ -782,6 +782,7 @@ struct dwc2_hsotg {
>  	u16 periodic_usecs;
>  	unsigned long periodic_bitmap[DIV_ROUND_UP(TOTAL_PERIODIC_USEC,
>  						   BITS_PER_LONG)];
> +	bool has_split[8];

why don't you use a u8 instead then just set each bit for each
"has_split" you need to take care of. This array is kinda ugly.

> @@ -386,6 +409,13 @@ static int dwc2_find_multi_uframe(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
>  	bitmap_set(hsotg->periodic_bitmap, start, qh->usecs);
>  	qh->start_usecs = start;
>  
> +	if (qh->do_split) {
> +		for (i = start / EARLY_FRAME_USEC;
> +		     i < DIV_ROUND_UP(start + utime - 1, EARLY_FRAME_USEC);
> +		     i++)
> +			hsotg->has_split[i] = true;

hsotg->has_split |= BIT(i);

> @@ -546,6 +577,13 @@ static void dwc2_deschedule_periodic(struct dwc2_hsotg *hsotg,
>  	}
>  
>  	bitmap_clear(hsotg->periodic_bitmap, start, utime);
> +
> +	if (qh->do_split) {
> +		for (i = start / EARLY_FRAME_USEC;
> +		     i < DIV_ROUND_UP(start + utime - 1, EARLY_FRAME_USEC);
> +		     i++)
> +			hsotg->has_split[i] = false;

hsotg->has_split &= ~BIT(i);

-- 
balbi

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