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From: Hans Verkuil <hverkuil@xs4all.nl>
To: Ezequiel Garcia <ezequiel@collabora.com>, linux-media@vger.kernel.org
Cc: kernel@collabora.com,
	Mauro Carvalho Chehab <mchehab@osg.samsung.com>,
	Shuah Khan <shuahkh@osg.samsung.com>,
	Pawel Osciak <pawel@osciak.com>,
	Alexandre Courbot <acourbot@chromium.org>,
	Sakari Ailus <sakari.ailus@iki.fi>,
	Brian Starkey <brian.starkey@arm.com>,
	linux-kernel@vger.kernel.org,
	Gustavo Padovan <gustavo.padovan@collabora.com>
Subject: Re: [PATCH v9 11/15] vb2: add in-fence support to QBUF
Date: Wed, 9 May 2018 09:04:40 +0200	[thread overview]
Message-ID: <0a4f2701-a699-3c28-559d-2bf638178b94@xs4all.nl> (raw)
In-Reply-To: <5541e08b048b932789db1c58438c2a2c2b6da7ce.camel@collabora.com>

On 05/08/2018 09:16 PM, Ezequiel Garcia wrote:
> On Mon, 2018-05-07 at 14:07 +0200, Hans Verkuil wrote:
>> On 04/05/18 22:06, Ezequiel Garcia wrote:
>>> @@ -1421,15 +1505,40 @@ int vb2_core_qbuf(struct vb2_queue *q, unsigned int index, void *pb)
>>>  	trace_vb2_qbuf(q, vb);
>>>  
>>>  	/*
>>> -	 * If already streaming, give the buffer to driver for processing.
>>> -	 * If not, the buffer will be given to driver on next streamon.
>>> +	 * For explicit synchronization: If the fence didn't signal
>>> +	 * yet we setup a callback to queue the buffer once the fence
>>> +	 * signals and then return successfully. But if the fence
>>> +	 * already signaled we lose the reference we held and queue the
>>> +	 * buffer to the driver.
>>
>> What happens if the fence signaled an error? Is that error returned to userspace?
>> (i.e. VIDIOC_QBUF will fail in that case)
>>
> 
> Hm, good question. If the fence signals with an error, we won't catch it apparently.
> We should fix dma_fence_add_callback to know about signaled vs. error signaled.

OK, so in the meantime we need a comment explaining this in the code. Perhaps as
a FIXME or TODO.

Regards,

	Hans

  reply	other threads:[~2018-05-09  7:04 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-04 20:05 [PATCH v9 00/15] V4L2 Explicit Synchronization Ezequiel Garcia
2018-05-04 20:05 ` [PATCH v9 01/15] xilinx: regroup caps on querycap Ezequiel Garcia
2018-05-04 20:05 ` [PATCH v9 02/15] hackrf: group device capabilities Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 03/15] omap3isp: " Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 04/15] vb2: move vb2_ops functions to videobuf2-core.[ch] Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 05/15] vb2: add unordered vb2_queue property for drivers Ezequiel Garcia
2018-05-07 11:03   ` Hans Verkuil
2018-05-04 20:06 ` [PATCH v9 06/15] v4l: add unordered flag to format description ioctl Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 07/15] v4l: mark unordered formats Ezequiel Garcia
2018-05-07 13:45   ` Hans Verkuil
2018-05-04 20:06 ` [PATCH v9 08/15] cobalt: set queue as unordered Ezequiel Garcia
2018-05-07 11:04   ` Hans Verkuil
2018-05-04 20:06 ` [PATCH v9 09/15] vb2: mark codec drivers " Ezequiel Garcia
2018-05-07 11:02   ` Hans Verkuil
2018-05-04 20:06 ` [PATCH v9 10/15] vb2: add explicit fence user API Ezequiel Garcia
2018-05-07 11:30   ` Hans Verkuil
2018-05-09 10:33   ` Brian Starkey
2018-05-09 15:52     ` Ezequiel Garcia
2018-05-09 16:33       ` Brian Starkey
2018-05-09 19:10         ` Ezequiel Garcia
2018-05-09 19:40         ` Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 11/15] vb2: add in-fence support to QBUF Ezequiel Garcia
2018-05-07 12:07   ` Hans Verkuil
2018-05-08 19:16     ` Ezequiel Garcia
2018-05-09  7:04       ` Hans Verkuil [this message]
2018-05-08 23:18     ` Gustavo Padovan
2018-05-09 10:35       ` Brian Starkey
2018-05-09 10:36   ` Brian Starkey
2018-05-09 10:52     ` Hans Verkuil
2018-05-09 16:03     ` Ezequiel Garcia
2018-05-09 16:45       ` Brian Starkey
2018-05-04 20:06 ` [PATCH v9 12/15] vb2: add out-fence " Ezequiel Garcia
2018-05-07 12:29   ` Hans Verkuil
2018-05-09 10:37   ` Brian Starkey
2018-05-04 20:06 ` [PATCH v9 13/15] v4l: introduce the fences capability Ezequiel Garcia
2018-05-04 20:06 ` [PATCH v9 14/15] v4l: Add V4L2_CAP_FENCES to drivers Ezequiel Garcia
2018-05-07 12:42   ` Hans Verkuil
2018-05-04 20:06 ` [PATCH v9 15/15] v4l: Document explicit synchronization behavior Ezequiel Garcia
2018-05-07 12:51   ` Hans Verkuil

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