From: "Guido Günther" <agx@sigxcpu.org>
To: "Ondřej Jirman" <megous@megous.com>,
"David Airlie" <airlied@linux.ie>,
"Daniel Vetter" <daniel@ffwll.ch>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Sam Ravnborg" <sam@ravnborg.org>,
"Fabio Estevam" <festevam@gmail.com>,
"Robert Chiras" <robert.chiras@nxp.com>,
"Samuel Holland" <samuel@sholland.org>,
dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 0/2] Fix st7703 panel initialization failures
Date: Sat, 18 Jul 2020 19:31:24 +0200 [thread overview]
Message-ID: <20200718173124.GA88021@bogon.m.sigxcpu.org> (raw)
In-Reply-To: <20200716143209.ud6ote4q545bo2c7@core.my.home>
Hi,
On Thu, Jul 16, 2020 at 04:32:09PM +0200, Ondřej Jirman wrote:
> Hi Guido,
>
> On Thu, Jul 16, 2020 at 04:08:43PM +0200, Guido Günther wrote:
> > Hi Ondrej,
> > On Thu, Jul 16, 2020 at 02:37:51PM +0200, Ondrej Jirman wrote:
> > > When extending the driver for xbd599 panel support I tried to do minimal
> > > changes and keep the existing initialization timing.
> > >
> > > It turned out that it's not good enough and the existing init sequence
> > > is too aggressive and doesn't follow the specification. On PinePhone
> > > panel is being powered down/up during suspend/resume and with current
> > > timings this frequently leads to corrupted display.
> >
> > Given the amount of ST7703 look alikes i don't think you can go by the
> > datasheet and hope not to break other panels. The current sleeps cater
> > for the rocktech panel (which suffered from similar issues you describe
> > when we took other parameters) so you need to make those panel specific.
>
> It should work on rocktech too. The patch mostly increases/reorders the delays
> slightly, to match the controller documentation. I don't see a reason to
> complicate the driver with per panel special delays, unless these patches don't
> work on your panel.
That's why i brought it up. It breaks the rocktech panel on
blank/unblank loops where it just stays blank and then starts hitting
DSI command timeouts.
Cheers,
-- Guido
>
> The init sequence is still suboptimal, and doesn't follow the kernel docs
> completely, even after these patches. Controller spec also talks about adding
> some delay before enabling the backlight to avoid visual glitches.
>
> Which is what enable callback is documented to be for. Currently part of the
> initialization that belongs to prepare callback is also done in enable callback.
>
> I see the glitch (small vertical shift of the image on powerup), but personally
> don't care much to introduce even more delays to the driver, just for the
> cosmetic issue.
>
> regards,
> o.
>
> > Cheers,
> > -- Guido
> >
> > >
> > > This patch series fixes the problems.
> > >
> > > The issue was reported by Samuel Holland.
> > >
> > > Relevant screenshots from the datasheet:
> > >
> > > Power on timing: https://megous.com/dl/tmp/35b72e674ce0ca27.png
> > > Power off timing: https://megous.com/dl/tmp/dea195517106ff17.png
> > > More optimal reset on poweron: https://megous.com/dl/tmp/a9e5caf14e1b0dc6.png
> > > Less optimal reset on poweron: https://megous.com/dl/tmp/246761039283c4cf.png
> > > Datasheet: https://megous.com/dl/tmp/ST7703_DS_v01_20160128.pdf
> > >
> > > Please take a look.
> > >
> > > thank you and regards,
> > > Ondrej Jirman
> > >
> > > Ondrej Jirman (2):
> > > drm/panel: st7703: Make the sleep exit timing match the spec
> > > drm/panel: st7703: Fix the power up sequence of the panel
> > >
> > > drivers/gpu/drm/panel/panel-sitronix-st7703.c | 29 ++++++++++---------
> > > 1 file changed, 15 insertions(+), 14 deletions(-)
> > >
> > > --
> > > 2.27.0
> > >
>
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next prev parent reply other threads:[~2020-07-18 17:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-16 12:37 [PATCH 0/2] Fix st7703 panel initialization failures Ondrej Jirman
2020-07-16 12:37 ` [PATCH 1/2] drm/panel: st7703: Make the sleep exit timing match the spec Ondrej Jirman
2020-07-16 12:37 ` [PATCH 2/2] drm/panel: st7703: Fix the power up sequence of the panel Ondrej Jirman
2020-07-16 14:08 ` [PATCH 0/2] Fix st7703 panel initialization failures Guido Günther
2020-07-16 14:32 ` Ondřej Jirman
2020-07-18 17:31 ` Guido Günther [this message]
2020-07-18 17:42 ` Ondřej Jirman
2020-07-29 15:48 ` Guido Günther
2020-07-30 13:41 ` Ondřej Jirman
2020-08-01 11:04 ` Guido Günther
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