linux-kernel - Re: [PATCH 7/9] media: cedrus: Move IRQ maintainance to cedrus_dec

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Date:   Mon, 25 Jun 2018 16:18:51 +0200
From:   Paul Kocialkowski <paul.kocialkowski@...tlin.com>
To:     Maxime Ripard <maxime.ripard@...tlin.com>, hans.verkuil@...co.com,
        acourbot@...omium.org, sakari.ailus@...ux.intel.com,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     tfiga@...omium.org, posciak@...omium.org,
        Chen-Yu Tsai <wens@...e.org>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        nicolas.dufresne@...labora.com, jenskuske@...il.com,
        linux-sunxi@...glegroups.com,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [PATCH 7/9] media: cedrus: Move IRQ maintainance to
 cedrus_dec_ops

Hi,

On Thu, 2018-06-21 at 17:35 +0200, Paul Kocialkowski wrote:
> Hi,
> 
> On Wed, 2018-06-13 at 16:07 +0200, Maxime Ripard wrote:
> > The IRQ handler up until now was hardcoding the use of the MPEG engine to
> > read the interrupt status, clear it and disable the interrupts.
> > 
> > Obviously, that won't work really well with the introduction of new codecs
> > that use a separate engine with a separate register set.
> > 
> > In order to make this more future proof, introduce new decodec operations
> > to deal with the interrupt management. The only one missing is the one to
> > enable the interrupts in the first place, but that's taken care of by the
> > trigger hook for now.
> 
> Acked-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>

Scratch that for now, I just thought of something here (see below).

> > Signed-off-by: Maxime Ripard <maxime.ripard@...tlin.com>
> > ---
> >  .../sunxi/cedrus/sunxi_cedrus_common.h        |  9 +++++
> >  .../platform/sunxi/cedrus/sunxi_cedrus_hw.c   | 21 ++++++------
> >  .../sunxi/cedrus/sunxi_cedrus_mpeg2.c         | 33 +++++++++++++++++++
> >  3 files changed, 53 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> > index c2e2c92d103b..a2a507eb9fc9 100644
> > --- a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> > +++ b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_common.h
> > @@ -108,7 +108,16 @@ struct sunxi_cedrus_buffer *vb2_to_cedrus_buffer(const struct vb2_buffer *p)
> >  	return vb2_v4l2_to_cedrus_buffer(to_vb2_v4l2_buffer(p));
> >  }
> >  
> > +enum sunxi_cedrus_irq_status {
> > +	SUNXI_CEDRUS_IRQ_NONE,
> > +	SUNXI_CEDRUS_IRQ_ERROR,
> > +	SUNXI_CEDRUS_IRQ_OK,
> > +};
> > +
> >  struct sunxi_cedrus_dec_ops {
> > +	void (*irq_clear)(struct sunxi_cedrus_ctx *ctx);
> > +	void (*irq_disable)(struct sunxi_cedrus_ctx *ctx);
> > +	enum sunxi_cedrus_irq_status (*irq_status)(struct sunxi_cedrus_ctx *ctx);
> >  	void (*setup)(struct sunxi_cedrus_ctx *ctx,
> >  		      struct sunxi_cedrus_run *run);
> >  	void (*trigger)(struct sunxi_cedrus_ctx *ctx);
> > diff --git a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_hw.c b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_hw.c
> > index bb46a01214e0..6b97cbd2834e 100644
> > --- a/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_hw.c
> > +++ b/drivers/media/platform/sunxi/cedrus/sunxi_cedrus_hw.c
> > @@ -77,27 +77,28 @@ static irqreturn_t sunxi_cedrus_ve_irq(int irq, void *dev_id)
> >  	struct sunxi_cedrus_ctx *ctx;
> >  	struct sunxi_cedrus_buffer *src_buffer, *dst_buffer;
> >  	struct vb2_v4l2_buffer *src_vb, *dst_vb;
> > +	enum sunxi_cedrus_irq_status status;
> >  	unsigned long flags;
> > -	unsigned int value, status;
> >  
> >  	spin_lock_irqsave(&dev->irq_lock, flags);
> >  
> > -	/* Disable MPEG interrupts and stop the MPEG engine */
> > -	value = sunxi_cedrus_read(dev, VE_MPEG_CTRL);
> > -	sunxi_cedrus_write(dev, value & (~0xf), VE_MPEG_CTRL);
> > -
> > -	status = sunxi_cedrus_read(dev, VE_MPEG_STATUS);
> > -	sunxi_cedrus_write(dev, 0x0000c00f, VE_MPEG_STATUS);
> > -	sunxi_cedrus_engine_disable(dev);
> > -
> >  	ctx = v4l2_m2m_get_curr_priv(dev->m2m_dev);
> >  	if (!ctx) {
> >  		pr_err("Instance released before the end of transaction\n");
> >  		spin_unlock_irqrestore(&dev->irq_lock, flags);
> >  
> > -		return IRQ_HANDLED;
> > +		return IRQ_NONE;
> >  	}
> >  
> > +	status = dev->dec_ops[ctx->current_codec]->irq_status(ctx);
> > +	if (status == SUNXI_CEDRUS_IRQ_NONE) {
> > +		spin_unlock_irqrestore(&dev->irq_lock, flags);
> > +		return IRQ_NONE;
> > +	}
> > +
> > +	dev->dec_ops[ctx->current_codec]->irq_disable(ctx);
> > +	dev->dec_ops[ctx->current_codec]->irq_clear(ctx);
> > +
> >  	src_vb = v4l2_m2m_src_buf_remove(ctx->fh.m2m_ctx);
> >  	dst_vb = v4l2_m2m_dst_buf_remove(ctx->fh.m2m_ctx);

Later in that file, there is still some checking that the first bit of
status is set:

	/* First bit of MPEG_STATUS indicates success. */
	if (ctx->job_abort || !(status & 0x01))

So !(status & 0x01) must be replaced with status != CEDRUS_IRQ_OK.

It seems that was working "by accident", with CEDRUS_IRQ_OK probably
being set by the compiler to 0x03.

Cheers,

Paul

-- 
Paul Kocialkowski, Bootlin (formerly Free Electrons)
Embedded Linux and kernel engineering
https://bootlin.com
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