On 09/15/2015 05:43 PM, Felipe Balbi wrote:
On Tue, Sep 15, 2015 at 05:37:27PM +0200, Krzysztof Opasiak wrote:
Hello,
On 09/15/2015 04:26 PM, Robert Baldyga wrote:
This patch introduces 'enabled' flag in struct usb_ep, and modifies
usb_ep_enable() and usb_ep_disable() functions to encapsulate endpoint
enabled/disabled state. It helps to avoid enabling endpoints which are
already enabled, and disabling endpoints which are already disables.
>From now USB functions don't have to remember current endpoint
enable/disable state, as this state is now handled automatically which
makes this API less bug-prone.
Signed-off-by: Robert Baldyga <r.baldyga@xxxxxxxxxxx>
---
include/linux/usb/gadget.h | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)
diff --git a/include/linux/usb/gadget.h b/include/linux/usb/gadget.h
index 3f299e2..63375cd 100644
--- a/include/linux/usb/gadget.h
+++ b/include/linux/usb/gadget.h
@@ -215,6 +215,7 @@ struct usb_ep {
struct list_head ep_list;
struct usb_ep_caps caps;
bool claimed;
+ bool enabled;
unsigned maxpacket:16;
unsigned maxpacket_limit:16;
unsigned max_streams:16;
@@ -264,7 +265,15 @@ static inline void usb_ep_set_maxpacket_limit(struct usb_ep *ep,
*/
static inline int usb_ep_enable(struct usb_ep *ep)
{
- return ep->ops->enable(ep, ep->desc);
+ int ret = 0;
+
+ if (!ep->enabled) {
+ ret = ep->ops->enable(ep, ep->desc);
+ if (!ret)
+ ep->enabled = true;
+ }
+
+ return ret;
}
/**
@@ -281,7 +290,15 @@ static inline int usb_ep_enable(struct usb_ep *ep)
*/
static inline int usb_ep_disable(struct usb_ep *ep)
{
- return ep->ops->disable(ep);
+ int ret = 0;
+
+ if (ep->enabled) {
+ ret = ep->ops->disable(ep);
+ if (!ret)
+ ep->enabled = false;
+ }
+
+ return ret;
}
Personally I don't like this convention. In my opinion usb_ep_disable() &
usb_ep_enable() should fail if ep is already disabled/enabled. Then in
function code we should check if endpoint is enabled (maybe even we should
have usb_ep_is_enabled()) and call disable only when it is really enabled.
usb_ep_is_enabled() should be a good addition but I don't see an issue
ignoring usb_ep_enabled() for something that's already enabled.
Imagine if you got an error when you tried to push the light switch to
the 'on' position while the light was already on :-p
Hmmm not sure right now, didn't test this recently :D as usually I check
if light isn't already "on" before I touch the switch to turn it on:P
Just joking. Personally I just prefer to don't touch things which are
already in desired condition. Let's take close() as example which could
be a little bit equivalent of our usb_ep_disable(). It is not legal to
call it twice on some fd and second call ends up with error.
Best regards,
--
Krzysztof Opasiak
Samsung R&D Institute Poland
Samsung Electronics
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