The panel-simple driver can already have devices instantiated as
platform devices or MIPI DSI devices. Let's add a 3rd way to
instantiate it: as DP AUX endpoint devices.
At the moment there is no benefit to instantiating it in this way,
but:
- In the next patch we'll give it access to the DDC channel via the DP
AUX bus.
- Possibly in the future we may use this channel to configure the
backlight.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.5.Iada41f76a7342354bae929d0bb3ceba40f27f0ea@changeid
The PM Runtime docs specifically call out the need to call
pm_runtime_dont_use_autosuspend() in the remove() callback if
pm_runtime_use_autosuspend() was called in probe():
> Drivers in ->remove() callback should undo the runtime PM changes done
> in ->probe(). Usually this means calling pm_runtime_disable(),
> pm_runtime_dont_use_autosuspend() etc.
We should do this. This fixes a warning splat that I saw when I was
testing out the panel-simple's remove().
Fixes: 3235b0f20a ("drm/panel: panel-simple: Use runtime pm to avoid excessive unprepare / prepare")
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210517130450.v7.1.I9e947183e95c9bd067c9c1d51208ac6a96385139@changeid
I don't believe that it ever makes sense to read the EDID when a panel
is not powered and the powering on of the panel is the job of
prepare(). Let's make sure that this happens before we try to read the
EDID. We use the pm_runtime functions directly rather than directly
calling the normal prepare() function because the pm_runtime functions
are definitely refcounted whereas it's less clear if the prepare() one
is.
NOTE: I'm not 100% sure how EDID reading was working for folks in the
past, but I can only assume that it was failing on the initial attempt
and then working only later. This patch, presumably, will fix that. If
some panel out there really can read the EDID without powering up and
it's a big advantage to preserve the old behavior we can add a
per-panel flag. It appears that providing the DDC bus to the panel in
the past was somewhat uncommon in any case.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.17.Ibd31b8f7c73255d68c5c9f5b611b4bfaa036f727@changeid
When I added support for the hpd-gpio to simple-panel in commit
48834e6084 ("drm/panel-simple: Support hpd-gpios for delaying
prepare()"), I added a special case to handle a circular dependency I
was running into on the ti-sn65dsi86 bridge chip. On my board the
hpd-gpio is actually provided by the bridge chip. That was causing
some circular dependency problems that I had to work around by getting
the hpd-gpio late.
I've now reorganized the ti-sn65dsi86 bridge chip driver to be a
collection of sub-drivers. Now the GPIO part can probe separately and
that breaks the chain. Let's get rid of the old code to clean things
up.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.10.I40eeedc23459d1e3fc96fa6cdad775d88c6e706c@changeid
Unpreparing and re-preparing a panel can be a really heavy
operation. Panels datasheets often specify something on the order of
500ms as the delay you should insert after turning off the panel
before turning it on again. In addition, turning on a panel can have
delays on the order of 100ms - 200ms before the panel will assert HPD
(AKA "panel ready"). The above means that we should avoid turning a
panel off if we're going to turn it on again shortly.
The above becomes a problem when we want to read the EDID of a
panel. The way that ordering works is that userspace wants to read the
EDID of the panel _before_ fully enabling it so that it can set the
initial mode correctly. However, we can't read the EDID until we power
it up. This leads to code that does this dance (like
ps8640_bridge_get_edid()):
1. When userspace requests EDID / the panel modes (through an ioctl),
we power on the panel just enough to read the EDID and then power
it off.
2. Userspace then turns the panel on.
There's likely not much time between step #1 and #2 and so we want to
avoid powering the panel off and on again between those two steps.
Let's use Runtime PM to help us. We'll move the existing prepare() and
unprepare() to be runtime resume() and runtime suspend(). Now when we
want to prepare() or unprepare() we just increment or decrement the
refcount. We'll default to a 1 second autosuspend delay which seems
sane given the typical delays we see for panels.
A few notes:
- It seems the existing unprepare() and prepare() are defined to be
no-ops if called extra times. We'll preserve that behavior but may
try to remove it in a future patch.
- This is a slight change in the ABI of simple panel. If something was
absolutely relying on the unprepare() to happen instantly that
simply won't be the case anymore. I'm not aware of anyone relying on
that behavior, but if there is someone then we'll need to figure out
how to enable (or disable) this new delayed behavior selectively.
- In order for this to work we now have a hard dependency on
"PM". From memory this is a legit thing to assume these days and we
don't have to find some fallback to keep working if someone wants to
build their system without "PM".
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210416153909.v4.7.I9e8bd33b49c496745bfac58ea9ab418bd3b6f5ce@changeid
Panel power sequence says timing T8 (time from link idle to turn on
the backlight) should be at least 50 ms. This is what the .enable
delay in simple-panel is for, so set it. NOTE: this overlaps with the
80 ms .prepare_to_enable delay on purpose. The data sheet says that
at least 80 ms needs to pass between HPD going high and turning on the
backlight and that at least 50 ms needs to pass between the link idle
and the backlight going on. Thus it works like this on the system in
front of me:
* In bridge chip pre_enable call drm_panel_prepare()
* drm_panel_prepare() -> panel_simple_prepare()
* Wait for HPD GPIO to go high.
* Start counting for 80 ms (store in prepared_time)
* In bridge chip enable, train link then call drm_panel_enable()
* drm_panel_enable() -> panel_simple_enable()
* panel_simple_enable() does hardcoded 50 ms delay then enforces 80 ms
from HPD going high (in case the bridge took less than 30 ms to
enable / link train).
* drm_panel_enable() -> backlight_enable().
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210222081716.1.I1a45aece5d2ac6a2e73bbec50da2086e43e0862b@changeid
On an Innolux N116BCA panel that I have in front of me, sometimes HPD
simply doesn't assert no matter how long you wait for it. As per the
very wise advice of The IT Crowd ("Have you tried turning it off and
on again?") it appears that power cycling is enough to kick this panel
back into a sane state.
>From tests on this panel, it appears that leaving it powered off for a
while stimulates the problem. Adding a 6 second sleep at the start of
panel_simple_prepare_once() makes it happen fairly reliably and, with
this delay, I saw up to 3 retries needed sometimes. Without the 6
second sleep, however, the panel came up much more reliably the first
time or after only 1 retry.
While it's unknown what the problems are with this panel (and probably
the hardware should be debugged), adding a few retries to the power on
routine doesn't seem insane. Even if this panel's problems are
attributed to the fact that it's pre-production and/or can be fixed,
retries clearly can help in some cases and really don't hurt.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210115144345.v2.3.I6916959daa7c5c915e889442268d23338de17923@changeid
Add support for the BOE NV110WTM-N61 panel. The EDID lists two modes
(one for 60 Hz refresh rate and one for 40 Hz), so we'll list both of
them here.
Note that the panel datasheet requires 80 ms between HPD asserting and
the backlight power being turned on. We'll use the new timing
constraints structure to do this cleanly. This assumes that the
backlight will be enabled _after_ the panel enable finishes. This is
how it works today and seems a sane assumption.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109170018.v4.4.I71b2118dfc00fd7b43b02d28e7b890081c2acfa2@changeid
On the panel I'm looking at, there's an 80 ms minimum time between HPD
being asserted by the panel and setting the backlight enable GPIO.
While we could just add an 80 ms "enable" delay, this is not ideal.
Link training is allowed to happen in parallel with this delay so the
fixed 80 ms delay over-delays.
We'll support this by logging the time at the end of prepare and then
delaying in enable if enough time hasn't passed.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109170018.v4.3.Ib9ce3c6482f464bf594161581521ced46bbd54ed@changeid
It is believed that all of the current users of the "unprepare" delay
don't actually need to wait the amount of time specified directly in
the unprepare phase. The purpose of the delay that's specified is to
allow the panel to fully power off so that we don't try to power it
back on before it's managed to full power down.
Let's use this observation to avoid the fixed delay that we currently
have. Instead of delaying, we'll note the current time when the
unprepare happens. If someone then tries to prepare the panel later
and not enough time has passed, we'll do the delay before starting the
prepare phase.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201109170018.v4.2.I06a95d83e7fa1bd919c8edd63dacacb5436e495a@changeid
Backmerging drm-next into drm-misc-next for nouveau and panel updates.
Resolves a conflict between ttm and nouveau, where struct ttm_mem_res got
renamed to struct ttm_resource.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Warn if we detect a panel with incomplete/wrong description.
This is inspired by a similar patch by Laurent that introduced checks
for LVDS panels - this extends the checks to the remaining type of
connectors.
This is known to warn for some of the existing panels but added
despite this as we need help from people using the panels to
add the missing info.
The checks are not complete but will catch the most common mistakes.
The checks at the same time serve as documentation for the minimum
required description for a panel.
The checks uses dev_warn() as we know this will hit. WARN() was
too noisy at the moment for anything else than LVDS.
v3:
- %d => %u for bpc (Laurent)
v2:
- Use dev_warn (Laurent)
- Check for empty bus_flags
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20200726203324.3722593-2-sam@ravnborg.org
