linux-kernel - Re: [PATCH 3/6] hantro: Rework how encoder and decoder are identified

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Message-ID: <119b9832-c1bc-9010-cca6-ea82d61c8e9b@arm.com>
Date:   Fri, 26 Jun 2020 10:52:23 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     Ezequiel Garcia <ezequiel@...labora.com>,
        linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Cc:     Hans Verkuil <hverkuil@...all.nl>, kernel@...labora.com,
        Philipp Zabel <p.zabel@...gutronix.de>
Subject: Re: [PATCH 3/6] hantro: Rework how encoder and decoder are identified

Hi Ezequiel,

On 2020-06-25 17:35, Ezequiel Garcia wrote:
> So far we've been using the .buf_finish hook to distinguish
> decoder from encoder. This is unnecessarily obfuscated.
> 
> Moreover, we want to move the buf_finish, so use a cleaner
> scheme to distinguish the driver decoder/encoder type.
> 
> Signed-off-by: Ezequiel Garcia <ezequiel@...labora.com>
> ---
>   drivers/staging/media/hantro/hantro.h     | 2 ++
>   drivers/staging/media/hantro/hantro_drv.c | 4 +++-
>   2 files changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/media/hantro/hantro.h b/drivers/staging/media/hantro/hantro.h
> index 3005207fc6fb..028b788ad50f 100644
> --- a/drivers/staging/media/hantro/hantro.h
> +++ b/drivers/staging/media/hantro/hantro.h
> @@ -199,6 +199,7 @@ struct hantro_dev {
>    *
>    * @dev:		VPU driver data to which the context belongs.
>    * @fh:			V4L2 file handler.
> + * @is_encoder:		Decoder or encoder context?
>    *
>    * @sequence_cap:       Sequence counter for capture queue
>    * @sequence_out:       Sequence counter for output queue
> @@ -223,6 +224,7 @@ struct hantro_dev {
>   struct hantro_ctx {
>   	struct hantro_dev *dev;
>   	struct v4l2_fh fh;
> +	bool is_encoder;
>   
>   	u32 sequence_cap;
>   	u32 sequence_out;
> diff --git a/drivers/staging/media/hantro/hantro_drv.c b/drivers/staging/media/hantro/hantro_drv.c
> index 0db8ad455160..112ed556eb90 100644
> --- a/drivers/staging/media/hantro/hantro_drv.c
> +++ b/drivers/staging/media/hantro/hantro_drv.c
> @@ -197,7 +197,7 @@ static void device_run(void *priv)
>   
>   bool hantro_is_encoder_ctx(const struct hantro_ctx *ctx)
>   {
> -	return ctx->buf_finish == hantro_enc_buf_finish;
> +	return ctx->is_encoder;

FWIW I'd suggest removing the wrapper function entirely now - it makes 
sense when the check itself is implemented in a weird and non-obvious 
way, but a simple boolean flag named exactly what it means is already 
about as clear as it can get.

Robin.

>   }
>   
>   static struct v4l2_m2m_ops vpu_m2m_ops = {
> @@ -420,8 +420,10 @@ static int hantro_open(struct file *filp)
>   	if (func->id == MEDIA_ENT_F_PROC_VIDEO_ENCODER) {
>   		allowed_codecs = vpu->variant->codec & HANTRO_ENCODERS;
>   		ctx->buf_finish = hantro_enc_buf_finish;
> +		ctx->is_encoder = true;
>   	} else if (func->id == MEDIA_ENT_F_PROC_VIDEO_DECODER) {
>   		allowed_codecs = vpu->variant->codec & HANTRO_DECODERS;
> +		ctx->is_encoder = false;
>   	} else {
>   		ret = -ENODEV;
>   		goto err_ctx_free;
>