From: Sergey Senozhatsky <senozhatsky@chromium.org>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>,
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 17:13:40 +0900 [thread overview]
Message-ID: <20200219081340.GA122464@google.com> (raw)
In-Reply-To: <be430540-4b8e-6b44-1eee-9d7291a365be@xs4all.nl>
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?
-ss
next prev parent reply other threads:[~2020-02-19 8:13 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 [this message]
2020-02-19 8:25 ` Hans Verkuil
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
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