linux-kernel - Re: [PATCH v5 00/39] i.MX Media Driver

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Date:   Sun, 19 Mar 2017 11:56:06 -0700
From:   Steve Longerbeam <slongerbeam@...il.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Steve Longerbeam <steve_longerbeam@...tor.com>,
        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,
        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 03/19/2017 11:51 AM, Russell King - ARM Linux wrote:
> On Sun, Mar 19, 2017 at 11:37:15AM -0700, Steve Longerbeam wrote:
>> On 03/19/2017 05:14 AM, Russell King - ARM Linux wrote:
>>> Right now, CSI doesn't do that - it only looks at the width, height,
>>> code, and field.
>> Correct, there is currently no propagation of the colorimetry
>> parameters (colorspace, ycbcr_enc, quantization, and xfer_func).
>> For the most part, those are just ignored ATM. Philipp Zabel did
>> do some work earlier to start propagating those, but that's still
>> TODO.
>
>>> I think we've got other bugs though that haven't been picked up by any
>>> review - csi_try_fmt() adjusts the format using the _current_
>>> configuration of the sink pad, even when using V4L2_SUBDEV_FORMAT_TRY.
>>> This seems wrong according to the docs: the purpose of the try
>>> mechanism is to be able to setup the _entire_ pipeline using the TRY
>>> mechanism to work out whether the configuration works, before then
>>> setting for real.  If we're validating the TRY formats against the
>>> live configuration, then we're not doing that.
>> I don't believe that is correct. csi_try_fmt() for the source pads calls
>> __csi_get_fmt(priv, cfg, CSI_SINK_PAD, sdformat->which) to get
>> the sink format, and for the TRY trial-run from csi_set_fmt(),
>> sdformat->which will be set to TRY, so the returned sink format
>> is the TRY format.
> Look at csi_try_fmt() - it validates the source pad against
> priv->crop, which is the actively live cropping rectangle, not the
> one which has been configured for the TRY trial-run.

Ah yes, crop, I missed that. Yes you are right, looks like we
need to add a __csi_get_crop().

>
> Also, as I mention elsewhere, I believe the way we're doing scaling
> is completely wrong...

You might be right there too. Initially, I had no support for the 
down-scaling
in the CSI. That was added later by Philipp, I will respond with more 
there...

Steve