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Date:   Tue, 23 May 2023 07:14:52 +0000
From:   Tomasz Figa <tfiga@chromium.org>
To:     Benjamin Gaignard <benjamin.gaignard@collabora.com>
Cc:     m.szyprowski@samsung.com, mchehab@kernel.org, ming.qian@nxp.com,
        shijie.qin@nxp.com, eagle.zhou@nxp.com, bin.liu@mediatek.com,
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        tiffany.lin@mediatek.com, andrew-ct.chen@mediatek.com,
        yunfei.dong@mediatek.com, stanimir.k.varbanov@gmail.com,
        quic_vgarodia@quicinc.com, agross@kernel.org, andersson@kernel.org,
        konrad.dybcio@linaro.org, ezequiel@vanguardiasur.com.ar,
        p.zabel@pengutronix.de, daniel.almeida@collabora.com,
        hverkuil-cisco@xs4all.nl, laurent.pinchart@ideasonboard.com,
        jernel@kernel.org, linux-media@vger.kernel.org,
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Subject: Re: [PATCH v2 4/8] media: videobuf2: Stop define VB2_MAX_FRAME as
 global
Message-ID: <20230523071452.2h2tilwrwejtmmrc@chromium.org>
References: <20230321102855.346732-1-benjamin.gaignard@collabora.com>
 <20230321102855.346732-5-benjamin.gaignard@collabora.com>
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In-Reply-To: <20230321102855.346732-5-benjamin.gaignard@collabora.com>
Precedence: bulk

On Tue, Mar 21, 2023 at 11:28:51AM +0100, Benjamin Gaignard wrote:
> After changing bufs arrays to a dynamic allocated array
> VB2_MAX_FRAME doesn't mean anything for videobuf2 core.
> Remove it from the core definitions but keep it for drivers internal
> needs.

This made me think that some drivers could behave really badly if they
get more than VB2_MAX_FRAME (or VIDEO_MAX_FRAME) buffers. I certainly
see some having fixed-size arrays of exactly that size. Should we have a
queue flag that enables more buffers, so it is only available for
drivers which can handle them?

Best regards,
Tomasz

> 
> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
>  drivers/media/common/videobuf2/videobuf2-core.c               | 2 ++
>  drivers/media/platform/amphion/vdec.c                         | 1 +
>  .../media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c | 2 ++
>  drivers/media/platform/qcom/venus/hfi.h                       | 2 ++
>  drivers/media/platform/verisilicon/hantro_hw.h                | 2 ++
>  drivers/staging/media/ipu3/ipu3-v4l2.c                        | 2 ++
>  include/media/videobuf2-core.h                                | 1 -
>  include/media/videobuf2-v4l2.h                                | 4 ----
>  8 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
> index f4da917ccf3f..3c6ced360770 100644
> --- a/drivers/media/common/videobuf2/videobuf2-core.c
> +++ b/drivers/media/common/videobuf2/videobuf2-core.c
> @@ -31,6 +31,8 @@
>  
>  #include <trace/events/vb2.h>
>  
> +#define VB2_MAX_FRAME	32
> +
>  static int debug;
>  module_param(debug, int, 0644);
>  
> diff --git a/drivers/media/platform/amphion/vdec.c b/drivers/media/platform/amphion/vdec.c
> index 87f9f8e90ab1..bef0c1b869be 100644
> --- a/drivers/media/platform/amphion/vdec.c
> +++ b/drivers/media/platform/amphion/vdec.c
> @@ -28,6 +28,7 @@
>  
>  #define VDEC_MIN_BUFFER_CAP		8
>  #define VDEC_MIN_BUFFER_OUT		8
> +#define VB2_MAX_FRAME			32
>  
>  struct vdec_fs_info {
>  	char name[8];
> diff --git a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> index f5958b6d834a..ba208caf3043 100644
> --- a/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> +++ b/drivers/media/platform/mediatek/vcodec/vdec/vdec_vp9_req_lat_if.c
> @@ -16,6 +16,8 @@
>  #include "../vdec_drv_if.h"
>  #include "../vdec_vpu_if.h"
>  
> +#define VB2_MAX_FRAME	32
> +
>  /* reset_frame_context defined in VP9 spec */
>  #define VP9_RESET_FRAME_CONTEXT_NONE0 0
>  #define VP9_RESET_FRAME_CONTEXT_NONE1 1
> diff --git a/drivers/media/platform/qcom/venus/hfi.h b/drivers/media/platform/qcom/venus/hfi.h
> index f25d412d6553..bd5ca5a8b945 100644
> --- a/drivers/media/platform/qcom/venus/hfi.h
> +++ b/drivers/media/platform/qcom/venus/hfi.h
> @@ -10,6 +10,8 @@
>  
>  #include "hfi_helper.h"
>  
> +#define VB2_MAX_FRAME				32
> +
>  #define VIDC_SESSION_TYPE_VPE			0
>  #define VIDC_SESSION_TYPE_ENC			1
>  #define VIDC_SESSION_TYPE_DEC			2
> diff --git a/drivers/media/platform/verisilicon/hantro_hw.h b/drivers/media/platform/verisilicon/hantro_hw.h
> index e83f0c523a30..9e8faf7ba6fb 100644
> --- a/drivers/media/platform/verisilicon/hantro_hw.h
> +++ b/drivers/media/platform/verisilicon/hantro_hw.h
> @@ -15,6 +15,8 @@
>  #include <media/v4l2-vp9.h>
>  #include <media/videobuf2-core.h>
>  
> +#define VB2_MAX_FRAME	32
> +
>  #define DEC_8190_ALIGN_MASK	0x07U
>  
>  #define MB_DIM			16
> diff --git a/drivers/staging/media/ipu3/ipu3-v4l2.c b/drivers/staging/media/ipu3/ipu3-v4l2.c
> index e530767e80a5..6627b5c2d4d6 100644
> --- a/drivers/staging/media/ipu3/ipu3-v4l2.c
> +++ b/drivers/staging/media/ipu3/ipu3-v4l2.c
> @@ -10,6 +10,8 @@
>  #include "ipu3.h"
>  #include "ipu3-dmamap.h"
>  
> +#define VB2_MAX_FRAME	32
> +
>  /******************** v4l2_subdev_ops ********************/
>  
>  #define IPU3_RUNNING_MODE_VIDEO		0
> diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
> index b8b34a993e04..4aa43c5c7c58 100644
> --- a/include/media/videobuf2-core.h
> +++ b/include/media/videobuf2-core.h
> @@ -21,7 +21,6 @@
>  #include <media/media-request.h>
>  #include <media/frame_vector.h>
>  
> -#define VB2_MAX_FRAME	(32)
>  #define VB2_MAX_PLANES	(8)
>  
>  /**
> diff --git a/include/media/videobuf2-v4l2.h b/include/media/videobuf2-v4l2.h
> index 5a845887850b..88a7a565170e 100644
> --- a/include/media/videobuf2-v4l2.h
> +++ b/include/media/videobuf2-v4l2.h
> @@ -15,10 +15,6 @@
>  #include <linux/videodev2.h>
>  #include <media/videobuf2-core.h>
>  
> -#if VB2_MAX_FRAME != VIDEO_MAX_FRAME
> -#error VB2_MAX_FRAME != VIDEO_MAX_FRAME
> -#endif
> -
>  #if VB2_MAX_PLANES != VIDEO_MAX_PLANES
>  #error VB2_MAX_PLANES != VIDEO_MAX_PLANES
>  #endif
> -- 
> 2.34.1
>