Message-ID: <20200608094432.GA27063@lxhi-065.adit-jv.com>
Date:   Mon, 8 Jun 2020 11:44:32 +0200
From:   Eugeniu Rosca <erosca@...adit-jv.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Jacopo Mondi <jacopo@...ndi.org>
CC:     <hien.dang.eb@...esas.com>, <michael.klein@...esas.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        <kieran.bingham+renesas@...asonboard.com>, <geert@...ux-m68k.org>,
        <horms@...ge.net.au>, <uli+renesas@...nd.eu>,
        <VenkataRajesh.Kalakodima@...bosch.com>, <airlied@...ux.ie>,
        <daniel@...ll.ch>, <koji.matsuoka.xm@...esas.com>,
        <muroya@....co.jp>, <Harsha.ManjulaMallikarjun@...bosch.com>,
        <ezequiel@...labora.com>, <seanpaul@...omium.org>,
        <linux-renesas-soc@...r.kernel.org>,
        <dri-devel@...ts.freedesktop.org>, <linux-kernel@...r.kernel.org>,
        <michael.dege@...esas.com>, <gotthard.voellmeke@...esas.com>,
        <efriedrich@...adit-jv.com>, <mrodin@...adit-jv.com>,
        <ChaitanyaKumar.Borah@...bosch.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>,
        Eugeniu Rosca <roscaeugeniu@...il.com>
Subject: Re: [PATCH v5 0/8] drm: rcar-du: Add Color Management Module (CMM)

Hello,

Many thanks for your comments and involvement.

On Sun, Jun 07, 2020 at 05:41:58AM +0300, Laurent Pinchart wrote:
> On Fri, Jun 05, 2020 at 03:53:15PM +0200, Jacopo Mondi wrote:
> > On Fri, Jun 05, 2020 at 03:41:24PM +0200, Eugeniu Rosca wrote:
> > > On Fri, Jun 05, 2020 at 03:29:00PM +0200, Jacopo Mondi wrote:
> > >> On Wed, May 27, 2020 at 09:15:55AM +0200, Eugeniu Rosca wrote:
> > >>> Could you kindly share the cross compilation steps for your kmsxx fork?
> > >>
> > >> I usually build it on the target :)
> > >
> > > Interesting approach. With ARM getting more and more potent, why not? :)
> > 
> > For 'small' utilities like kmsxx it's doable
> > 
> > >>> Just out of curiosity, have you ever tried to pull the display's HDMI
> > >>> cable while reading from CM2_LUT_TBL?
> > >>
> > >> Ahem, not really :) Did I get you right, you mean disconnecting the
> > >> HDMI cable from the board ?
> > >
> > > Right.
> > 
> > So, no, I have not tried. Do you see any intersting failure with the
> > mainline version ?
> 
> Jacopo, would you be able to give this a try ?

FWIW, I seem to hit pre-existing issues in vanilla rcar-du,
while unplugging HDMI cable during a cyclic suspend-resume:

HW: H3 ES2.0 Salvator-X
SW: renesas-drivers-2020-06-02-v5.7
.config: renesas_defconfig +CONFIG_PM_DEBUG +CONFIG_PM_ADVANCED_DEBUG
Use-case:

  --------8<---------
$ cat s2ram.sh
modprobe i2c-dev
echo 9 > /proc/sys/kernel/printk
i2cset -f -y 7 0x30 0x20 0x0F
echo 0 > /sys/module/suspend/parameters/pm_test_delay
echo core  > /sys/power/pm_test
echo deep > /sys/power/mem_sleep
echo 1 > /sys/power/pm_debug_messages
echo 0 > /sys/power/pm_print_times
echo mem > /sys/power/state

$ while true; do sh s2ram.sh ; done
$ # unplug HDMI cable several times

[   55.568051] PM: noirq resume of devices complete after 3.862 msecs
[   55.583253] PM: early resume of devices complete after 8.496 msecs
[   65.757023] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:74:crtc-1] flip_done timed out
[   75.996123] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:74:crtc-1] flip_done timed out
[   86.236112] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CRTC:74:crtc-1] flip_done timed out
[   96.476111] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CONNECTOR:80:HDMI-A-1] flip_done timed out
[  106.716109] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [PLANE:45:plane-5] flip_done timed out
[  116.956111] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:74:crtc-1] flip_done timed out
[  127.196112] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CRTC:74:crtc-1] flip_done timed out
[  137.436116] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [CONNECTOR:80:HDMI-A-1] flip_done timed out
[  147.676111] [drm:drm_atomic_helper_wait_for_dependencies] *ERROR* [PLANE:45:plane-5] flip_done timed out
[  157.916110] [drm:drm_atomic_helper_wait_for_flip_done] *ERROR* [CRTC:74:crtc-1] flip_done timed out
  --------8<---------

This looks to be unrelated to the CMM lockup I initially reported.

JYI, graphics pipelines in production R-Car3 targets are significantly
more complex (involving binding/unbinding serializer ICs at runtime
during non-trivial shutdown/suspend/resume sequences), as opposed
to the relatively straightforward VGA/HDMI outputs present on the
reference targets. So, my hope is that Renesas community can take
HDMI hot plugging seriously and make it a regular test-case during
rcar-du patch review, since this is a precondition for the R-Car3
platform and products to succeed as a whole.

BTW, if you happen to know an affordable programmable HDMI switcher
which can do the hot-plugging job in an automated test environment,
please let me know.

> 
> > >>> At least with the out-of-tree CMM implementation [*], this sends the
> > >>> R-Car3 reference targets into an unrecoverable freeze, with no lockup
> > >>> reported by the kernel (i.e. looks like an serious HW issue).
> > >>>
> > >>>> CMM functionalities are retained between suspend/resume cycles (tested with
> > >>>> suspend-to-idle) without requiring a re-programming of the LUT tables.
> > >>>
> > >>> Hmm. Is this backed up by any statement in the HW User's manual?
> > >>> This comes in contrast with the original Renesas CMM implementation [**]
> > >>> which does make use of suspend (where the freeze actually happens).
> > >>>
> > >>> Can we infer, based on your statement, that we could also get rid of
> > >>> the suspend callback in [**]?
> > >>
> > >> As Geert (thanks) explained what I've tested with is suspend-to-idle,
> > >> which retains the state of the LUT tables (and I assume other
> > >> not-yet-implemented CMM features, like CLU). I recall the out-of-tree
> > >> driver has suspend/resume routines but I never really tested that.
> > >
> > > I see. JFYI, there is a flaw in the suspend handling in the out-of-tree
> > > CMM patch [*], which renders the SoC unresponsive on HDMI hotplug. The
> > > fix is currently under review. Hopefully it will make its way to [*]
> > > in the nearest future. Just to keep in mind for the moment when CMM
> > > s2ram will become a mainline feature.
> > 
> > Thanks, let's keep this in mind. Next week I'll run a few tests again
> > with s2ram and will get back to you.
> 
> Note that the CMM driver is controlled by the DU driver. As the DU
> driver will reenable the display during resume, it will call
> rcar_du_cmm_setup() at resume time, which will reprogram the CMM. There
> should thus be no need for manual suspend/resume handling in the CMM as
> far as I can tell, but we need to ensure that the CMM is suspended
> before and resumed after the DU. I believe this could be implemented
> using device links.

Does this apply to vanilla rcar-du only (where CMM support differs
from [*]) or would also be relevant for rcar.9.6 kernel?

> 
> > >>> [*] https://github.com/renesas-rcar/du_cmm
> > >>> [**] https://github.com/renesas-rcar/du_cmm/blob/c393ed49834bdbc/meta-rcar-gen3/recipes-kernel/linux/linux-renesas/0001-drm-rcar-du-Add-DU-CMM-support.patch#L1912

-- 
Best regards,
Eugeniu Rosca

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