Message-ID: <1593592121.4007.33.camel@mhfsdcap03>
Date:   Wed, 1 Jul 2020 16:28:41 +0800
From:   Xia Jiang <xia.jiang@...iatek.com>
To:     Tomasz Figa <tfiga@...omium.org>
CC:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Matthias Brugger" <matthias.bgg@...il.com>,
        Rick Chang <rick.chang@...iatek.com>,
        <linux-media@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        <srv_heupstream@...iatek.com>, <senozhatsky@...omium.org>,
        <mojahsu@...omium.org>, <drinkcat@...omium.org>,
        <maoguang.meng@...iatek.com>, <sj.huang@...iatek.com>
Subject: Re: [PATCH RESEND v9 18/18] media: platform: Add jpeg enc feature

On Tue, 2020-06-30 at 16:53 +0000, Tomasz Figa wrote:
> Hi Xia,
> 
> On Tue, Jun 30, 2020 at 10:56:21AM +0800, Xia Jiang wrote:
> > On Thu, 2020-06-11 at 18:46 +0000, Tomasz Figa wrote:
> > > Hi Xia,
> > > 
> > > On Thu, Jun 04, 2020 at 05:05:53PM +0800, Xia Jiang wrote:
> [snip]
> > > > +static void mtk_jpeg_enc_device_run(void *priv)
> > > > +{
> > > > +	struct mtk_jpeg_ctx *ctx = priv;
> > > > +	struct mtk_jpeg_dev *jpeg = ctx->jpeg;
> > > > +	struct vb2_v4l2_buffer *src_buf, *dst_buf;
> > > > +	enum vb2_buffer_state buf_state = VB2_BUF_STATE_ERROR;
> > > > +	unsigned long flags;
> > > > +	struct mtk_jpeg_src_buf *jpeg_src_buf;
> > > > +	struct mtk_jpeg_enc_bs enc_bs;
> > > > +	int ret;
> > > > +
> > > > +	src_buf = v4l2_m2m_next_src_buf(ctx->fh.m2m_ctx);
> > > > +	dst_buf = v4l2_m2m_next_dst_buf(ctx->fh.m2m_ctx);
> > > > +	jpeg_src_buf = mtk_jpeg_vb2_to_srcbuf(&src_buf->vb2_buf);
> > > > +
> > > > +	ret = pm_runtime_get_sync(jpeg->dev);
> > > > +	if (ret < 0)
> > > > +		goto enc_end;
> > > > +
> > > > +	spin_lock_irqsave(&jpeg->hw_lock, flags);
> > > > +
> > > > +	/*
> > > > +	 * Resetting the hardware every frame is to ensure that all the
> > > > +	 * registers are cleared. This is a hardware requirement.
> > > > +	 */
> > > > +	mtk_jpeg_enc_reset(jpeg->reg_base);
> > > > +
> > > > +	mtk_jpeg_set_enc_dst(ctx, jpeg->reg_base, &dst_buf->vb2_buf, &enc_bs);
> > > > +	mtk_jpeg_set_enc_src(ctx, jpeg->reg_base, &src_buf->vb2_buf);
> > > > +	mtk_jpeg_enc_set_config(jpeg->reg_base, ctx->out_q.fmt->hw_format,
> > > > +				ctx->enable_exif, ctx->enc_quality,
> > > > +				ctx->restart_interval);
> > > > +	mtk_jpeg_enc_start(jpeg->reg_base);
> > > 
> > > Could we just move the above 5 functions into one function inside
> > > mtk_jpeg_enc_hw.c that takes mtk_jpeg_dev pointer as its argument, let's
> > > say mtk_jpeg_enc_hw_run() and simply program all the data to the registers
> > > directly, without the extra level of abstractions?
> > I can move the 5 functions into one function(mtk_jpeg_enc_hw_run()), but
> > this function will be very long, because it contains computation code
> > such as setting dst addr, blk_num, quality.
> > In v4, you have adviced the following architecture:
> > How about the following model, as used by many other drivers:
> > 
> > mtk_jpeg_enc_set_src()
> > {
> >         // Set any registers related to source format and buffer
> > }
> > 
> > mtk_jpeg_enc_set_dst()
> > {
> >         // Set any registers related to destination format and buffer
> > }
> > 
> > mtk_jpeg_enc_set_params()
> > {
> >         // Set any registers related to additional encoding parameters
> > }
> > 
> > mtk_jpeg_enc_device_run(enc, ctx)
> > {
> >         mtk_jpeg_enc_set_src(enc, src_buf, src_fmt);
> >         mtk_jpeg_enc_set_dst(enc, dst_buf, dst_fmt);
> >         mtk_jpeg_enc_set_params(enc, ctx);
> >         // Trigger the hardware run
> > }
> > I think that this architecture is more clear(mtk_jpeg_enc_set_config is
> > equivalent to mtk_jpeg_enc_set_params).
> > Should I keep the original architecture or move 5 functions into
> > mtk_jpeg_enc_hw_run?
> 
> Sounds good to me.
> 
> My biggest issue with the code that it ends up introducing one more
> level of abstraction, but with the approach you suggested, the arguments
> just accept standard structs, which avoids that problem.
Dear Tomasz,

Sorry for that I didn't understand your final preference.

As you mentioned, using mtk_jpeg_dev pointer as its argument, but some
arguments come from mtk_jpeg_ctx pointer, such as ctx->enable_exif/
ctx->enc_quality/ctx->restart_interval. Should we use  mtk_jpeg_ctx
pointer as its argument? Should we use src_dma_addr/dst_dma_addr as its
arguments too? Because that src_dma_addr/dst_dma_addr need to be getted
by v4l2 interfaces(
src_buf=v4l2_m2m_next_src_buf();
src_dma_ddr=vb2_dma_contig_plane_dma_addr();). 
Using V4L2 interfaces in mtk_jpeg_enc_hw.c doesn't seem reasonable.

solution 1:
mtk_jpeg_enc_hw_run(ctx, src_dma_addr, dst_dma_addr)
{
	//Set all the registers
without one more level of abstraction
}

solution 2:
mtk_jpeg_enc_reset(jpeg)
{
	//set the reset register
}

mtk_jpeg_set_enc_dst(ctx, dst_dma_addr)
{
	
	//Set any registers related to destination format and buffer
without one more level of abstraction
}
mtk_jpeg_set_enc_src(ctx, src_dma_addr)
{

	//Set any registers related to source format and buffer     without one
more level of abstraction
}
mtk_jpeg_enc_set_config(ctx)
{
	// Set any registers related to additional encoding parameters
without one more level of abstraction
}
mtk_jpeg_enc_start(jpeg)
{
	//set the trigger register
}

Solution 1 or Solution 2?

Best Regards,
Xia Jiang
> 
> [snip]
> > > > +
> > > > +	ctx->fh.ctrl_handler = &ctx->ctrl_hdl;
> > > > +	ctx->colorspace = V4L2_COLORSPACE_JPEG,
> > > > +	ctx->ycbcr_enc = V4L2_YCBCR_ENC_DEFAULT;
> > > > +	ctx->quantization = V4L2_QUANTIZATION_DEFAULT;
> > > > +	ctx->xfer_func = V4L2_XFER_FUNC_DEFAULT;
> > > 
> > > Since we already have a v4l2_pix_format_mplane struct which has fields for
> > > the above 4 values, could we just store them there?
> > > 
> > > Also, I don't see this driver handling the colorspaces in any way, but it
> > > seems to allow changing them from the userspace. This is incorrect, because
> > > the userspace has no way to know that the colorspace is not handled.
> > > Instead, the try_fmt implementation should always override the
> > > userspace-provided colorspace configuration with the ones that the driver
> > > assumes.
> > > 
> > > > +	pix_mp->width = MTK_JPEG_MIN_WIDTH;
> > > > +	pix_mp->height = MTK_JPEG_MIN_HEIGHT;
> > > > +
> > > > +	q->fmt = mtk_jpeg_find_format(V4L2_PIX_FMT_YUYV,
> > > > +				      MTK_JPEG_FMT_FLAG_ENC_OUTPUT);
> > > > +	vidioc_try_fmt(container_of(pix_mp, struct v4l2_format,
> > > > +				    fmt.pix_mp), q->fmt);
> > > > +	q->w = pix_mp->width;
> > > > +	q->h = pix_mp->height;
> > > > +	q->crop_rect.width = pix_mp->width;
> > > > +	q->crop_rect.height = pix_mp->height;
> > > > +	q->sizeimage[0] = pix_mp->plane_fmt[0].sizeimage;
> > > > +	q->bytesperline[0] = pix_mp->plane_fmt[0].bytesperline;
> > > 
> > > Actually, do we need this custom mtk_jpeg_q_data struct? Why couldn't we
> > > just keep the same values inside the standard v4l2_pix_format_mplane
> > > struct?
> > I think that we need mtk_jpeg_q_data struct.If we delete it, how can we
> > know these values(w, h, sizeimage, bytesperline, mtk_jpeg_fmt) belong to
> > output or capture(output and capture's sizeimages are different, width
> > and height are differnt too for jpeg dec )?We have
> > s_fmt_vid_out_mplane/cap_mplane function to set these values.
> > 
> > But we can use standard v4l2_pix_format_mplane struct replacing the w, h
> > bytesperline, sizeimage in mtk_jpeg_q_data struct like this:
> > struct mtk_jpeg_q_data{
> > 	struct mtk_jpeg_fmt *fmt;
> > 	struct v4l2_pix_format_mplane pix_mp;
> > 	struct v4l2_rect enc_crop_rect
> > }
> > Then delete ctx->colorspace ctx->ycbcr_enc ctx->quantization
> > ctx->xfer_func, becuase v4l2_pix_format_mplane in q_data has contained
> > them and assign them for out_q and cap_q separately.
> > 
> > WDYT?
> 
> Sounds good to me. I was considering just making it like
> 
> struct mtk_jpeg_ctx {
> 	struct mtk_jpeg_fmt *src_fmt;
> 	struct v4l2_pix_format_mplane src_pix_mp;
> 	struct v4l2_rect src_crop;
> 
> 	struct mtk_jpeg_fmt *dst_fmt;
> 	struct v4l2_pix_format_mplane dst_pix_mp;
> 	struct v4l2_rect dst_crop;
> };
> 
> but I like your suggestion as well, as long as custom data structures
> are not used to store standard information.
> [snip]
> > > > @@ -1042,8 +1619,12 @@ static int mtk_jpeg_probe(struct platform_device *pdev)
> > > >  		return jpeg_irq;
> > > >  	}
> > > >  
> > > > -	ret = devm_request_irq(&pdev->dev, jpeg_irq, mtk_jpeg_dec_irq, 0,
> > > > -			       pdev->name, jpeg);
> > > > +	if (jpeg->variant->is_encoder)
> > > > +		ret = devm_request_irq(&pdev->dev, jpeg_irq, mtk_jpeg_enc_irq,
> > > > +				       0, pdev->name, jpeg);
> > > > +	else
> > > > +		ret = devm_request_irq(&pdev->dev, jpeg_irq, mtk_jpeg_dec_irq,
> > > > +				       0, pdev->name, jpeg);
> > > 
> > > Rather than having "is_encoder" in the variant struct, would it make more
> > > sense to have "irq_handler" instead? That would avoid the explicit if.
> > Do you mean to delete "is_encoder"? It is used 8 times in the
> > driver.Should I move them all to the match data?
> 
> Yes. It would make the code linear and the varability between the
> decoder and encoder would be self-contained in the variant struct.
> 
> Best regards,
> Tomasz

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