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Date:   Tue, 8 Feb 2022 03:26:31 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Alexander Stein <alexander.stein@ew.tq-group.com>
Cc:     Steve Longerbeam <slongerbeam@gmail.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>,
        Rui Miguel Silva <rmfrfs@gmail.com>,
        Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>,
        linux-media@vger.kernel.org, linux-staging@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: (EXT) Re: [PATCH 1/8] media: imx: Store the type of hardware
 implementation
Message-ID: <YgHGxzSOfTglmp+r@pendragon.ideasonboard.com>
References: <20220204121514.2762676-1-alexander.stein@ew.tq-group.com>
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 <Yf3tPuwbyz5UU6eC@pendragon.ideasonboard.com>
 <3650787.kQq0lBPeGt@steina-w>
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Hi Alexander,

On Mon, Feb 07, 2022 at 10:22:25AM +0100, Alexander Stein wrote:
> Am Samstag, 5. Februar 2022, 04:21:34 CET schrieb Laurent Pinchart:
> > On Fri, Feb 04, 2022 at 01:15:07PM +0100, Alexander Stein wrote:
> > > From: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > 
> > > The driver covers i.MX5/6, as well as i.MX7/8 hardware.
> > > Those implementations differ, e.g. in the sizes of buffers they accept.
> > > 
> > > Some functionality should be abstracted, and storing type achieves that.
> > 
> > I think that longer term (which ideally shouldn't be too far in the
> > future) we should decouple the i.MX5/6 and i.MX7/8 drivers (this naming
> > is actually not quite correct, there are i.MX6 SoCs that have a CSI
> > bridge, not an IPUv3). The platforms are completely different at the
> > hardware level, they shouldn't share the same code. That would allow us
> > to evolve the CSI bridge driver independently from the IPUv3 driver, and
> > move it from staging to drivers/media/.
> 
> That sounds reasonable. Although I'm not sure where to start. Split it for 
> i.MX6 in the first place (CSI bridge vs. IPUv3)? Or start splitting across 
> i.MX generation? I've yet to have broad knowledge about the internals to be 
> able to come up with a good decision.

There are only two camera interfaces supported in this directory at this
point, IPUv3 and CSI bridge (the latter implemented in imx7-media-csi).
There's no need to split across i.MX generations.

> > I'm not against merging this if it can help short term, but please also
> > feel free to start decoupling the drivers, even if it results in some
> > duplicated code.
> 
> Thanks for willing to accept this short term patches. I'm hesitating to 
> decoupling for now as I haven't fully grasped all the details and small 
> similarities and differences.

I started giving it a try, but it will take some more work.

> > > Signed-off-by: Dorota Czaplejewicz <dorota.czaplejewicz@puri.sm>
> > > Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
> > > ---
> > > Changes in comparison to original commit from Dorota:
> > > * Applied the suggestion from Hans at [1].
> > > 
> > > [1] https://patchwork.linuxtv.org/project/linux-media/patch/20211104113631.206899-2-dorota.czaplejewicz@puri.sm/
> > >  drivers/staging/media/imx/imx-ic-prpencvf.c   | 3 ++-
> > >  drivers/staging/media/imx/imx-media-capture.c | 5 ++++-
> > >  drivers/staging/media/imx/imx-media-csi.c     | 3 ++-
> > >  drivers/staging/media/imx/imx-media.h         | 3 ++-
> > >  drivers/staging/media/imx/imx7-media-csi.c    | 3 ++-
> > >  5 files changed, 12 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/staging/media/imx/imx-ic-prpencvf.c b/drivers/staging/media/imx/imx-ic-prpencvf.c
> > > index 9b81cfbcd777..caaaac1a515a 100644
> > > --- a/drivers/staging/media/imx/imx-ic-prpencvf.c
> > > +++ b/drivers/staging/media/imx/imx-ic-prpencvf.c
> > > @@ -1266,7 +1266,8 @@ static int prp_registered(struct v4l2_subdev *sd)
> > > 
> > >  	priv->vdev = imx_media_capture_device_init(ic_priv->ipu_dev,
> > >  						   &ic_priv->sd,
> > > -						   PRPENCVF_SRC_PAD, true);
> > > +						   PRPENCVF_SRC_PAD, true,
> > > +						   true);
> > >  	if (IS_ERR(priv->vdev))
> > >  		return PTR_ERR(priv->vdev);
> > > 
> > > diff --git a/drivers/staging/media/imx/imx-media-capture.c b/drivers/staging/media/imx/imx-media-capture.c
> > > index 93ba09236010..b61bf9f8ddf8 100644
> > > --- a/drivers/staging/media/imx/imx-media-capture.c
> > > +++ b/drivers/staging/media/imx/imx-media-capture.c
> > > @@ -47,6 +47,7 @@ struct capture_priv {
> > > 
> > >  	struct v4l2_ctrl_handler ctrl_hdlr;	/* Controls inherited from subdevs */
> > >  	
> > >  	bool legacy_api;			/* Use the legacy (pre-MC) API */
> > > +	bool is_imx56;				/* Hardware is i.MX5/i.MX6 */
> > 
> > Can we create an enum type instead, to make the code more explicit ?
> 
> I don't mind. So I will pick up the original patches from Dorota at [1] 
> instead which already had an enum.
> 
> [1] https://patchwork.kernel.org/project/linux-arm-kernel/patch/
> 20211104113631.206899-2-dorota.czaplejewicz@puri.sm/
> 
> > >  };
> > >  
> > >  #define to_capture_priv(v) container_of(v, struct capture_priv, vdev)
> > > @@ -957,7 +958,8 @@
> > > EXPORT_SYMBOL_GPL(imx_media_capture_device_unregister);
> > >  struct imx_media_video_dev *
> > >  imx_media_capture_device_init(struct device *dev, struct v4l2_subdev *src_sd,
> > > -			      int pad, bool legacy_api)
> > > +			      int pad, bool legacy_api,
> > > +			      bool is_imx56)
> > >  {
> > >  	struct capture_priv *priv;
> > >  	struct video_device *vfd;
> > > @@ -972,6 +974,7 @@ imx_media_capture_device_init(struct device *dev, struct v4l2_subdev *src_sd,
> > >  	priv->src_sd_pad = pad;
> > >  	priv->dev = dev;
> > >  	priv->legacy_api = legacy_api;
> > > +	priv->is_imx56 = is_imx56;
> > > 
> > >  	mutex_init(&priv->mutex);
> > >  	INIT_LIST_HEAD(&priv->ready_q);
> > > diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
> > > index bd7f156f2d52..c8f6add00dbb 100644
> > > --- a/drivers/staging/media/imx/imx-media-csi.c
> > > +++ b/drivers/staging/media/imx/imx-media-csi.c
> > > @@ -1803,7 +1803,8 @@ static int csi_registered(struct v4l2_subdev *sd)
> > >  	}
> > >  	
> > >  	priv->vdev = imx_media_capture_device_init(priv->sd.dev, &priv->sd,
> > > -						   CSI_SRC_PAD_IDMAC, true);
> > > +						   CSI_SRC_PAD_IDMAC, true,
> > > +						   true);
> > >  	if (IS_ERR(priv->vdev)) {
> > >  		ret = PTR_ERR(priv->vdev);
> > >  		goto free_fim;
> > > diff --git a/drivers/staging/media/imx/imx-media.h b/drivers/staging/media/imx/imx-media.h
> > > index f263fc3adbb9..73e8e6e0d8e8 100644
> > > --- a/drivers/staging/media/imx/imx-media.h
> > > +++ b/drivers/staging/media/imx/imx-media.h
> > > @@ -282,7 +282,8 @@ int imx_media_ic_unregister(struct v4l2_subdev *sd);
> > >  /* imx-media-capture.c */
> > >  struct imx_media_video_dev *
> > >  imx_media_capture_device_init(struct device *dev, struct v4l2_subdev *src_sd,
> > > -			      int pad, bool legacy_api);
> > > +			      int pad, bool legacy_api,
> > > +			      bool is_imx56);
> > >  void imx_media_capture_device_remove(struct imx_media_video_dev *vdev);
> > >  int imx_media_capture_device_register(struct imx_media_video_dev *vdev,
> > >  				      u32 link_flags);
> > > diff --git a/drivers/staging/media/imx/imx7-media-csi.c b/drivers/staging/media/imx/imx7-media-csi.c
> > > index 32311fc0e2a4..158d2a736c6d 100644
> > > --- a/drivers/staging/media/imx/imx7-media-csi.c
> > > +++ b/drivers/staging/media/imx/imx7-media-csi.c
> > > @@ -1039,7 +1039,8 @@ static int imx7_csi_registered(struct v4l2_subdev *sd)
> > >  	}
> > >  	
> > >  	csi->vdev = imx_media_capture_device_init(csi->sd.dev, &csi->sd,
> > > -						  IMX7_CSI_PAD_SRC, false);
> > > +						  IMX7_CSI_PAD_SRC, false,
> > > +						  false);
> > >  	if (IS_ERR(csi->vdev))
> > >  		return PTR_ERR(csi->vdev);
> > > 

-- 
Regards,

Laurent Pinchart