Date:   Mon, 13 Mar 2017 09:30:07 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Steve Longerbeam <slongerbeam@...il.com>
Cc:     mark.rutland@....com, andrew-ct.chen@...iatek.com,
        minghsiu.tsai@...iatek.com, sakari.ailus@...ux.intel.com,
        nick@...anahar.org, songjun.wu@...rochip.com, hverkuil@...all.nl,
        Steve Longerbeam <steve_longerbeam@...tor.com>, pavel@....cz,
        robert.jarzmik@...e.fr, devel@...verdev.osuosl.org,
        markus.heiser@...marIT.de,
        laurent.pinchart+renesas@...asonboard.com, shuah@...nel.org,
        geert@...ux-m68k.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, kernel@...gutronix.de, arnd@...db.de,
        mchehab@...nel.org, bparrot@...com, robh+dt@...nel.org,
        horms+renesas@...ge.net.au, tiffany.lin@...iatek.com,
        linux-arm-kernel@...ts.infradead.org,
        niklas.soderlund+renesas@...natech.se, gregkh@...uxfoundation.org,
        linux-kernel@...r.kernel.org, jean-christophe.trotin@...com,
        p.zabel@...gutronix.de, fabio.estevam@....com, shawnguo@...nel.org,
        sudipm.mukherjee@...il.com
Subject: Re: [PATCH v5 00/39] i.MX Media Driver

On Mon, Mar 13, 2017 at 08:16:25AM +0000, Russell King - ARM Linux wrote:
> On Sun, Mar 12, 2017 at 09:26:41PM -0700, Steve Longerbeam wrote:
> > On 03/12/2017 01:22 PM, Russell King - ARM Linux wrote:
> > >What I had was this patch for your v3.  I never got to testing your
> > >v4 because of the LP-11 problem.
> > >
> > >In v5, you've changed to propagate the ipu_cpmem_set_image() error
> > >code to avoid the resulting corruption, but that leaves the other bits
> > >of this patch unaddressed, along my "media: imx: smfc: add support
> > >for bayer formats" patch.
> > >
> > >Your driver basically has no support for bayer formats.
> > 
> > You added the patches to this driver that adds the bayer support,
> > I don't think there is anything more required of the driver at this
> > point to support bayer, the remaining work needs to happen in the IPUv3
> > driver.
> 
> There is more work, because the way you've merged my changes to
> imx_smfc_setup_channel() into csi_idmac_setup_channel() is wrong with
> respect to the burst size.
> 
> You always set it to 8 or 16 depending on the width:
> 
> 	burst_size = (image.pix.width & 0xf) ? 8 : 16;
> 
> 	ipu_cpmem_set_burstsize(priv->idmac_ch, burst_size);
> 
> and then you have my switch() statement which assigns burst_size.
> My _tested_ code removed the above, added the switch, which had
> a default case which reflected the above setting:
> 
> 	default:
> 		burst_size = (outfmt->width & 0xf) ? 8 : 16;
> 
> and then went on to set the burst size _after_ the switch statement:
> 
> 	ipu_cpmem_set_burstsize(priv->smfc_ch, burst_size);
> 
> The effect is unchanged for non-bayer formats.  For bayer formats, the
> burst size is determined by the bayer data size.
> 
> So, even if it's appropriate to fix ipu_cpmem_set_image(), fixing the
> above is still required.
> 
> I'm not convinced that fixing ipu_cpmem_set_image() is even the best
> solution - it's not as trivial as it looks on the surface:
> 
>         ipu_cpmem_set_resolution(ch, image->rect.width, image->rect.height);
>         ipu_cpmem_set_stride(ch, pix->bytesperline);
> 
> this is fine, it doesn't depend on the format.  However, the next line:
> 
>         ipu_cpmem_set_fmt(ch, v4l2_pix_fmt_to_drm_fourcc(pix->pixelformat));
> 
> does - v4l2_pix_fmt_to_drm_fourcc() is a locally defined function (it
> isn't v4l2 code) that converts a v4l2 pixel format to a DRM fourcc.
> DRM knows nothing about bayer formats, there aren't fourcc codes in
> DRM for it.  The result is that v4l2_pix_fmt_to_drm_fourcc() returns
> -EINVAL cast to a u32, which gets passed unchecked into ipu_cpmem_set_fmt().
> 
> ipu_cpmem_set_fmt() won't recognise that, and also returns -EINVAL - and
> it's a bug that this is not checked and propagated.  If it is checked and
> propagated, then we need this to support bayer formats, and I don't see
> DRM people wanting bayer format fourcc codes added without there being
> a real DRM driver wanting to use them.
> 
> Then there's the business of calculating the top-left offset of the image,
> which for bayer always needs to be an even number of pixels - as this
> function takes the top-left offset, it ought to respect it, but if it
> doesn't meet this criteria, what should it do?  csi_idmac_setup_channel()
> always sets them to zero, but that's not really something that
> ipu_cpmem_set_image() should assume.

For the time being, I've restored the functionality along the same lines
as I originally had.  This seems to get me working capture, but might
break non-bayer passthrough mode:

diff --git a/drivers/staging/media/imx/imx-media-csi.c b/drivers/staging/media/imx/imx-media-csi.c
index fc0036aa84d0..df336971a009 100644
--- a/drivers/staging/media/imx/imx-media-csi.c
+++ b/drivers/staging/media/imx/imx-media-csi.c
@@ -314,14 +314,6 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
 	image.phys0 = phys[0];
 	image.phys1 = phys[1];
 
-	ret = ipu_cpmem_set_image(priv->idmac_ch, &image);
-	if (ret)
-		return ret;
-
-	burst_size = (image.pix.width & 0xf) ? 8 : 16;
-
-	ipu_cpmem_set_burstsize(priv->idmac_ch, burst_size);
-
 	/*
 	 * Check for conditions that require the IPU to handle the
 	 * data internally as generic data, aka passthrough mode:
@@ -346,15 +338,29 @@ static int csi_idmac_setup_channel(struct csi_priv *priv)
 		passthrough_bits = 16;
 		break;
 	default:
+		burst_size = (image.pix.width & 0xf) ? 8 : 16;
 		passthrough = (sensor_ep->bus_type != V4L2_MBUS_CSI2 &&
 			       sensor_ep->bus.parallel.bus_width >= 16);
 		passthrough_bits = 16;
 		break;
 	}
 
-	if (passthrough)
+	if (passthrough) {
+		ipu_cpmem_set_resolution(priv->idmac_ch, image.rect.width,
+					 image.rect.height);
+		ipu_cpmem_set_stride(priv->idmac_ch, image.pix.bytesperline);
+		ipu_cpmem_set_buffer(priv->idmac_ch, 0, image.phys0);
+		ipu_cpmem_set_buffer(priv->idmac_ch, 1, image.phys1);
+		ipu_cpmem_set_burstsize(priv->idmac_ch, burst_size);
 		ipu_cpmem_set_format_passthrough(priv->idmac_ch,
 						 passthrough_bits);
+	} else {
+		ret = ipu_cpmem_set_image(priv->idmac_ch, &image);
+		if (ret)
+			return ret;
+
+		ipu_cpmem_set_burstsize(priv->idmac_ch, burst_size);
+	}
 
 	/*
 	 * Set the channel for the direct CSI-->memory via SMFC


-- 
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