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[209.85.210.49]) by smtp.gmail.com with ESMTPSA id k16sm1942332otj.58.2019.08.30.02.48.49 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Aug 2019 02:48:50 -0700 (PDT) Received: by mail-ot1-f49.google.com with SMTP id 97so3523435otr.4 for ; Fri, 30 Aug 2019 02:48:49 -0700 (PDT) X-Received: by 2002:a9d:4817:: with SMTP id c23mr10736054otf.97.1567158529318; Fri, 30 Aug 2019 02:48:49 -0700 (PDT) MIME-Version: 1.0 References: <20190822194500.2071-1-jernej.skrabec@siol.net> <20190822194500.2071-3-jernej.skrabec@siol.net> <907f3c43-b994-f1c7-a15b-116566e19003@xs4all.nl> In-Reply-To: <907f3c43-b994-f1c7-a15b-116566e19003@xs4all.nl> From: Alexandre Courbot Date: Fri, 30 Aug 2019 18:48:36 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH 2/8] videodev2.h: add V4L2_DEC_CMD_FLUSH To: Hans Verkuil Cc: Jernej Skrabec , Mauro Carvalho Chehab , Paul Kocialkowski , mripard@kernel.org, Pawel Osciak , Marek Szyprowski , Kyungmin Park , Tomasz Figa , Chen-Yu Tsai , gregkh@linuxfoundation.org, Linux Media Mailing List , LKML , devel@driverdev.osuosl.org, "moderated list:ARM/Mediatek SoC support" , Ezequiel Garcia , jonas@kwiboo.se Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 30, 2019 at 6:45 PM Hans Verkuil wrote: > > On 8/30/19 11:38 AM, Alexandre Courbot wrote: > > On Fri, Aug 23, 2019 at 4:45 AM Jernej Skrabec wrote: > >> > >> From: Hans Verkuil > >> > >> Add this new V4L2_DEC_CMD_FLUSH decoder command and document it. > >> > >> Signed-off-by: Hans Verkuil > >> Signed-off-by: Jernej Skrabec > >> --- > >> Documentation/media/uapi/v4l/vidioc-decoder-cmd.rst | 11 ++++++++++- > >> Documentation/media/videodev2.h.rst.exceptions | 1 + > >> include/uapi/linux/videodev2.h | 1 + > >> 3 files changed, 12 insertions(+), 1 deletion(-) > >> > >> diff --git a/Documentation/media/uapi/v4l/vidioc-decoder-cmd.rst b/Documentation/media/uapi/v4l/vidioc-decoder-cmd.rst > >> index 57f0066f4cff..0bffef6058f7 100644 > >> --- a/Documentation/media/uapi/v4l/vidioc-decoder-cmd.rst > >> +++ b/Documentation/media/uapi/v4l/vidioc-decoder-cmd.rst > >> @@ -208,7 +208,16 @@ introduced in Linux 3.3. They are, however, mandatory for stateful mem2mem decod > >> been started yet, the driver will return an ``EPERM`` error code. When > >> the decoder is already running, this command does nothing. No > >> flags are defined for this command. > >> - > >> + * - ``V4L2_DEC_CMD_FLUSH`` > >> + - 4 > >> + - Flush any held capture buffers. Only valid for stateless decoders, > >> + and only if ``V4L2_BUF_CAP_SUPPORTS_M2M_HOLD_CAPTURE_BUF`` was set. > >> + This command is typically used when the application reached the > >> + end of the stream and the last output buffer had the > >> + ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` flag set. This would prevent > >> + dequeueing the last capture buffer containing the last decoded frame. > >> + So this command can be used to explicitly flush that last decoded > >> + frame. > > > > Just for safety, can we also specify that it is valid to call this > > command even if no buffer was held (in which case it is a no-op), as > > this can help make user-space code simpler? > > Ah yes, thanks for the reminder. > > Jernej, when you post the next version of this series, can you change the text > above to: > > - Flush any held capture buffers. Only valid for stateless decoders. > This command is typically used when the application reached the > end of the stream and the last output buffer had the > ``V4L2_BUF_FLAG_M2M_HOLD_CAPTURE_BUF`` flag set. This would prevent > dequeueing the capture buffer containing the last decoded frame. > So this command can be used to explicitly flush that final decoded > frame. This command does nothing if there are no held capture buffers. With the above, Reviewed-by: Alexandre Courbot Thanks! > > Regards, > > Hans > > > > >> > >> Return Value > >> ============ > >> diff --git a/Documentation/media/videodev2.h.rst.exceptions b/Documentation/media/videodev2.h.rst.exceptions > >> index adeb6b7a15cb..a79028e4d929 100644 > >> --- a/Documentation/media/videodev2.h.rst.exceptions > >> +++ b/Documentation/media/videodev2.h.rst.exceptions > >> @@ -434,6 +434,7 @@ replace define V4L2_DEC_CMD_START decoder-cmds > >> replace define V4L2_DEC_CMD_STOP decoder-cmds > >> replace define V4L2_DEC_CMD_PAUSE decoder-cmds > >> replace define V4L2_DEC_CMD_RESUME decoder-cmds > >> +replace define V4L2_DEC_CMD_FLUSH decoder-cmds > >> > >> replace define V4L2_DEC_CMD_START_MUTE_AUDIO decoder-cmds > >> replace define V4L2_DEC_CMD_PAUSE_TO_BLACK decoder-cmds > >> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h > >> index 4fa9f543742d..91a79e16089c 100644 > >> --- a/include/uapi/linux/videodev2.h > >> +++ b/include/uapi/linux/videodev2.h > >> @@ -1978,6 +1978,7 @@ struct v4l2_encoder_cmd { > >> #define V4L2_DEC_CMD_STOP (1) > >> #define V4L2_DEC_CMD_PAUSE (2) > >> #define V4L2_DEC_CMD_RESUME (3) > >> +#define V4L2_DEC_CMD_FLUSH (4) > >> > >> /* Flags for V4L2_DEC_CMD_START */ > >> #define V4L2_DEC_CMD_START_MUTE_AUDIO (1 << 0) > >> -- > >> 2.22.1 > >> >