linux-kernel - RE: [PATCH v5 02/46] usb: gadget: add endpoint capabilities flags

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Date:	Fri, 31 Jul 2015 15:51:52 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Robert Baldyga' <r.baldyga@...sung.com>,
	"balbi@...com" <balbi@...com>
CC:	"nicolas.ferre@...el.com" <nicolas.ferre@...el.com>,
	"robert.jarzmik@...e.fr" <robert.jarzmik@...e.fr>,
	"m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
	"devel@...verdev.osuosl.org" <devel@...verdev.osuosl.org>,
	"cernekee@...il.com" <cernekee@...il.com>,
	"michal.simek@...inx.com" <michal.simek@...inx.com>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"Peter.Chen@...escale.com" <Peter.Chen@...escale.com>,
	"dahlmann.thomas@...or.de" <dahlmann.thomas@...or.de>,
	"johnyoun@...opsys.com" <johnyoun@...opsys.com>,
	"linux-geode@...ts.infradead.org" <linux-geode@...ts.infradead.org>,
	"haojian.zhuang@...il.com" <haojian.zhuang@...il.com>,
	"andrzej.p@...sung.com" <andrzej.p@...sung.com>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"petr.cvek@....cz" <petr.cvek@....cz>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"daniel@...que.org" <daniel@...que.org>
Subject: RE: [PATCH v5 02/46] usb: gadget: add endpoint capabilities flags

From: Robert Baldyga
> Sent: 31 July 2015 15:00
> Introduce struct usb_ep_caps which contains information about capabilities
> of usb endpoints - supported transfer types and directions. This structure
> should be filled by UDC driver for each of its endpoints, and will be
> used in epautoconf in new ep matching mechanism which will replace ugly
> guessing of endpoint capabilities basing on its name.
> 
> Signed-off-by: Robert Baldyga <r.baldyga@...sung.com>
> ---
>  include/linux/usb/gadget.h | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
> 
> diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
> index 68fb5e8..a9a4959 100644
> --- a/include/linux/usb/gadget.h
> +++ b/include/linux/usb/gadget.h
> @@ -141,10 +141,29 @@ struct usb_ep_ops {
>  };
...
> +struct usb_ep_caps {
> +	unsigned type_control:1;
> +	unsigned type_iso:1;
> +	unsigned type_bulk:1;
> +	unsigned type_int:1;
> +	unsigned dir_in:1;
> +	unsigned dir_out:1;
> +};

With the way this is used (eg below from 13/46)

+
+		if (i == 0) {
+			ep->ep.caps.type_control = true;
+		} else {
+			ep->ep.caps.type_iso = true;
+			ep->ep.caps.type_bulk = true;
+			ep->ep.caps.type_int = true;
+		}
+
+		ep->ep.caps.dir_in = true;
+		ep->ep.caps.dir_out = true;

I think it would be more obvious if you used a u8 and explicit bitmasks.
The initialisation (as above) would the be explicitly assigning 'not supported'
to the other fields.
The compiler will also generate much better code...

	David