Date:   Fri, 12 Jun 2020 17:12:09 +0200
From:   Jacopo Mondi <jacopo@...ndi.org>
To:     Eugeniu Rosca <erosca@...adit-jv.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        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 <roscaeugeniu@...il.com>
Subject: Re: [PATCH v5 0/8] drm: rcar-du: Add Color Management Module (CMM)

Hi Eugeniu

On Mon, Jun 08, 2020 at 11:44:32AM +0200, Eugeniu Rosca wrote:
> 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

According to
https://elinux.org/R-Car/Boards/Salvator-X#Suspend-to-RAM
this is not needed anymore

> 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

I tried unplugging an plugging the cable while the system was
suspended and after resume but I was not able to reproduce anything.

Could you provide more precise instructions on how to reproduce this ?
I.e. when to disconnect the cable to trigger the below error.

Thanks
  j

>
> [   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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