linux-kernel - Re: [PATCH v4 00/36] i.MX Media Driver

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Message-ID: <20170217122213.GQ16975@valkosipuli.retiisi.org.uk>
Date:   Fri, 17 Feb 2017 14:22:14 +0200
From:   Sakari Ailus <sakari.ailus@....fi>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     Steve Longerbeam <slongerbeam@...il.com>,
        Russell King - ARM Linux <linux@...linux.org.uk>,
        robh+dt@...nel.org, mark.rutland@....com, shawnguo@...nel.org,
        kernel@...gutronix.de, fabio.estevam@....com, mchehab@...nel.org,
        hverkuil@...all.nl, nick@...anahar.org, markus.heiser@...marIT.de,
        laurent.pinchart+renesas@...asonboard.com, bparrot@...com,
        geert@...ux-m68k.org, arnd@...db.de, sudipm.mukherjee@...il.com,
        minghsiu.tsai@...iatek.com, tiffany.lin@...iatek.com,
        jean-christophe.trotin@...com, horms+renesas@...ge.net.au,
        niklas.soderlund+renesas@...natech.se, robert.jarzmik@...e.fr,
        songjun.wu@...rochip.com, andrew-ct.chen@...iatek.com,
        gregkh@...uxfoundation.org, shuah@...nel.org,
        sakari.ailus@...ux.intel.com, pavel@....cz,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        devel@...verdev.osuosl.org,
        Steve Longerbeam <steve_longerbeam@...tor.com>
Subject: Re: [PATCH v4 00/36] i.MX Media Driver

Hi Philipp, Steve and Russell,

On Fri, Feb 17, 2017 at 12:43:38PM +0100, Philipp Zabel wrote:
> On Thu, 2017-02-16 at 14:27 -0800, Steve Longerbeam wrote:
> > 
> > On 02/16/2017 02:20 PM, Russell King - ARM Linux wrote:
> > > On Wed, Feb 15, 2017 at 06:19:02PM -0800, Steve Longerbeam wrote:
> > >> In version 4:
> > >
> > > With this version, I get:
> > >
> > > [28762.892053] imx6-mipi-csi2: LP-11 timeout, phy_state = 0x00000000
> > > [28762.899409] ipu1_csi0: pipeline_set_stream failed with -110
> > >
> > 
> > Right, in the imx219, on exit from s_power(), the clock and data lanes
> > must be placed in the LP-11 state. This has been done in the ov5640 and
> > tc358743 subdevs.
> > 
> > If we want to bring in the patch that adds a .prepare_stream() op,
> > the csi-2 bus would need to be placed in LP-11 in that op instead.
> > 
> > Philipp, should I go ahead and add your .prepare_stream() patch?
> 
> I think with Russell's explanation of how the imx219 sensor operates,
> we'll have to do something before calling the sensor s_stream, but right
> now I'm still unsure what exactly.

Indeed there appears to be no other way to achieve the LP-11 state than
going through the streaming state for this particular sensor, apart from
starting streaming.

Is there a particular reason why you're waiting for the transmitter to
transfer to LP-11 state? That appears to be the last step which is done in
the csi2_s_stream() callback.

What the sensor does next is to start streaming, and the first thing it does
in that process is to switch to LP-11 state.

Have you tried what happens if you simply drop the LP-11 check? To me that
would seem the right thing to do.

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus@....fi	XMPP: sailus@...iisi.org.uk