From: Hans Verkuil <hverkuil@xs4all.nl>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Hans Verkuil <hans.verkuil@cisco.com>,
Tomasz Figa <tfiga@chromium.org>,
Mauro Carvalho Chehab <mchehab@kernel.org>,
Kyungmin Park <kyungmin.park@samsung.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Sakari Ailus <sakari.ailus@iki.fi>,
Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
Pawel Osciak <posciak@chromium.org>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCHv2 02/12] videobuf2: handle V4L2 buffer cache flags
Date: Wed, 19 Feb 2020 09:25:29 +0100 [thread overview]
Message-ID: <2b1d9855-48dd-ecfe-7a7c-5998f76c3cd8@xs4all.nl> (raw)
In-Reply-To: <20200219081340.GA122464@google.com>
On 2/19/20 9:13 AM, Sergey Senozhatsky wrote:
> On (20/02/19 09:07), Hans Verkuil wrote:
> [..]
>>> +static void set_buffer_cache_hints(struct vb2_queue *q,
>>> + struct vb2_buffer *vb,
>>> + struct v4l2_buffer *b)
>>> +{
>>> + /*
>>> + * DMA exporter should take care of cache syncs, so we can avoid
>>> + * explicit ->prepare()/->finish() syncs. For other ->memory types
>>> + * we always need ->prepare() or/and ->finish() cache sync.
>>> + */
>>> + if (q->memory == VB2_MEMORY_DMABUF) {
>>> + vb->need_cache_sync_on_finish = 0;
>>> + vb->need_cache_sync_on_prepare = 0;
>>> + return;
>>> + }
>>> +
>>> + if (!q->allow_cache_hints)
>>> + return;
>>> +
>>> + vb->need_cache_sync_on_prepare = 1;
>>
>> This needs a comment explaining why prepare is set to 1 by default. I remember
>> we discussed this earlier, and the conclusion of that discussion needs to be
>> documented here in a comment.
>
> Please ignore this patch. There is a follow up which sets _both_
> flags by default. The purpose is to preserve the existing behaviour,
> we can do all sorts of incremental changes (clear flags in more cases,
> etc.) later on. Do you want me to document this in the code?
Yes please!
Regards,
Hans
>
> -ss
>
next prev parent reply other threads:[~2020-02-19 8:25 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-04 2:56 [RFC][PATCHv2 00/12] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 01/12] videobuf2: add cache management members Sergey Senozhatsky
2020-02-19 8:05 ` Hans Verkuil
2020-02-19 8:16 ` Sergey Senozhatsky
2020-02-19 8:27 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 02/12] videobuf2: handle V4L2 buffer cache flags Sergey Senozhatsky
2020-02-05 8:13 ` Sergey Senozhatsky
2020-02-19 8:07 ` Hans Verkuil
2020-02-19 8:13 ` Sergey Senozhatsky
2020-02-19 8:25 ` Hans Verkuil [this message]
2020-02-19 8:46 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 03/12] videobuf2: add V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-02-13 7:08 ` Tomasz Figa
2020-02-19 8:19 ` Hans Verkuil
2020-02-19 8:56 ` Hans Verkuil
2020-02-25 7:45 ` Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 04/12] videobuf2: add queue memory consistency parameter Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 05/12] videobuf2: handle V4L2_FLAG_MEMORY_NON_CONSISTENT flag Sergey Senozhatsky
2020-02-19 8:25 ` Hans Verkuil
2020-02-19 8:59 ` Sergey Senozhatsky
2020-02-19 9:04 ` Hans Verkuil
2020-02-19 8:48 ` Hans Verkuil
2020-02-19 9:05 ` Sergey Senozhatsky
2020-02-19 9:11 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 06/12] videobuf2: factor out planes prepare/finish functions Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 07/12] videobuf2: do not sync caches when we are allowed not to Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 08/12] videobuf2: check ->synced flag in prepare() and finish() Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 09/12] videobuf2: let user-space know if driver supports cache hints Sergey Senozhatsky
2020-02-19 8:33 ` Hans Verkuil
2020-02-19 8:45 ` Sergey Senozhatsky
2020-02-19 8:56 ` Hans Verkuil
2020-02-04 2:56 ` [RFC][PATCHv2 10/12] videobuf2: add begin/end cpu_access callbacks to dma-contig Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 11/12] videobuf2: add begin/end cpu_access callbacks to dma-sg Sergey Senozhatsky
2020-02-19 8:35 ` Hans Verkuil
2020-02-19 8:42 ` Sergey Senozhatsky
2020-02-04 2:56 ` [RFC][PATCHv2 12/12] videobuf2: don't test db_attach in dma-contig prepare and finish Sergey Senozhatsky
2020-02-19 8:53 ` [RFC][PATCHv2 00/12] Implement V4L2_BUF_FLAG_NO_CACHE_* flags Hans Verkuil
2020-02-26 11:20 ` Sergey Senozhatsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=2b1d9855-48dd-ecfe-7a7c-5998f76c3cd8@xs4all.nl \
--to=hverkuil@xs4all.nl \
--cc=hans.verkuil@cisco.com \
--cc=kyungmin.park@samsung.com \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=m.szyprowski@samsung.com \
--cc=mchehab@kernel.org \
--cc=posciak@chromium.org \
--cc=sakari.ailus@iki.fi \
--cc=senozhatsky@chromium.org \
--cc=tfiga@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).