From: Greg KH <gregkh@linuxfoundation.org>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Michael Grzeschik <m.grzeschik@pengutronix.de>,
linux-usb@vger.kernel.org, linux-media@vger.kernel.org,
dan.scally@ideasonboard.com, nicolas@ndufresne.ca,
kernel@pengutronix.de
Subject: Re: [PATCH v2 1/3] usb: gadget: uvc: stop pump thread on video disable
Date: Thu, 5 Oct 2023 10:40:10 +0200 [thread overview]
Message-ID: <2023100557-crabbing-superhero-02f9@gregkh> (raw)
In-Reply-To: <20231005081716.GA13853@pendragon.ideasonboard.com>
On Thu, Oct 05, 2023 at 11:17:16AM +0300, Laurent Pinchart wrote:
> Hi Michael,
>
> Thank you for the patch.
>
> On Mon, Sep 11, 2023 at 04:05:28PM +0200, Michael Grzeschik wrote:
> > Since the uvc-video gadget driver is using the v4l2 interface,
> > the streamon and streamoff can be triggered at any times. To ensure
> > that the pump worker will be closed as soon the userspace is
> > calling streamoff we synchronize the state of the gadget ensuring
> > the pump worker to bail out.
>
> I'm sorry but I really dislike this. Not only does the patch fail to
> ensure real synchronization, as the uvcg_video_pump() function still
> runs asynchronously, it messes up the usage of the state field that now
> tracks the state both from a host point of view (which it was doing so
> far, updating the state based on callbacks from the UDC), and from a
> gadget userspace point of view. This lacks clarity and is confusing.
> Furthermore, the commit message doesn't even explain what issue is being
> fixed here.
>
> Greg, I think this series has been merged too soon :-(
Ok, I'll go revert them now, thanks for the review.
greg k-h
next prev parent reply other threads:[~2023-10-05 8:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-11 14:05 [PATCH v2 0/3] usb: gadget: uvc: restart fixes Michael Grzeschik
2023-09-11 14:05 ` [PATCH v2 1/3] usb: gadget: uvc: stop pump thread on video disable Michael Grzeschik
2023-10-05 8:17 ` Laurent Pinchart
2023-10-05 8:40 ` Greg KH [this message]
2023-10-05 8:48 ` Laurent Pinchart
2023-10-05 8:58 ` Greg KH
2023-09-11 14:05 ` [PATCH v2 2/3] usb: gadget: uvc: cleanup request when not in correct state Michael Grzeschik
2023-10-05 8:21 ` Laurent Pinchart
2023-09-11 14:05 ` [PATCH v2 3/3] usb: gadget: uvc: rework pump worker to avoid while loop Michael Grzeschik
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