On its own, this change looks a little strange and doesn't do too much
useful. To understand why we're doing this we need to look forward to
future patches where we're going to probe our panel using the new DP
AUX bus. See the patch ("drm/bridge: ti-sn65dsi86: Add support for the
DP AUX bus").
Let's think about the set of steps we'll want to happen when we have
the DP AUX bus:
1. We'll create the DP AUX bus.
2. We'll populate the devices on the DP AUX bus (AKA our panel).
3. For setting up the bridge-related functions of ti-sn65dsi86 we'll
need to get a reference to the panel.
If we do #1 - #3 in a single probe call things _mostly_ will work, but
it won't be massively robust. Let's explore.
First let's think of the easy case of no -EPROBE_DEFER. In that case
in step #2 when we populate the devices on the DP AUX bus it will
actually try probing the panel right away. Since the panel probe
doesn't defer then in step #3 we'll get a reference to the panel and
we're golden.
Second, let's think of the case when the panel returns
-EPROBE_DEFER. In that case step #2 won't synchronously create the
panel (it'll just add the device to the defer list to do it
later). Step #3 will fail to get the panel and the bridge sub-device
will return -EPROBE_DEFER. We'll depopulate the DP AUX bus. Later
we'll try the whole sequence again. Presumably the panel will
eventually stop returning -EPROBE_DEFER and we'll go back to the first
case where things were golden. So this case is OK too even if it's a
bit ugly that we have to keep creating / deleting the AUX bus over and
over.
So where is the problem? As I said, it's mostly about robustness. I
don't believe that step #2 (creating the sub-devices) is really
guaranteed to be synchronous. This is evidenced by the fact that it's
allowed to "succeed" by just sticking the device on the deferred
list. If anything about the process changes in Linux as a whole and
step #2 just kicks off the probe of the DP AUX endpoints (our panel)
in the background then we'd be in trouble because we might never get
the panel in step #3.
Adding an extra sub-device means we just don't need to worry about
it. We'll create the sub-device for the DP AUX bus and it won't go
away until the whole ti-sn65dsi86 driver goes away. If the bridge
sub-device defers (maybe because it can't find the panel) that won't
depopulate the DP AUX bus and so we don't need to worry about it.
NOTE: there's a little bit of a trick here. Though the AUX channel can
run without the MIPI-to-eDP bits of the code, the MIPI-to-eDP bits
can't run without the AUX channel. We could come up a complicated
signaling scheme (have the MIPI-to-eDP bits return EPROBE_DEFER for a
while or wait on some sort of completion), but it seems simple enough
to just not even bother creating the bridge device until the AUX
channel probes. That's what we'll do.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210611101711.v10.7.If89144992cb9d900f8c91a8d1817dbe00f543720@changeid
Fix the following sparse warnings generated by "make C=1":
drivers/gpu/drm/bridge/ti-sn65dsi83.c:429:13: warning: incorrect type in assignment (different base types)
drivers/gpu/drm/bridge/ti-sn65dsi83.c:429:13: expected unsigned short [assigned] [usertype] val
drivers/gpu/drm/bridge/ti-sn65dsi83.c:429:13: got restricted __le16 [usertype]
drivers/gpu/drm/bridge/ti-sn65dsi83.c:432:13: warning: incorrect type in assignment (different base types)
drivers/gpu/drm/bridge/ti-sn65dsi83.c:432:13: expected unsigned short [addressable] [assigned] [usertype] val
drivers/gpu/drm/bridge/ti-sn65dsi83.c:432:13: got restricted __le16 [usertype]
drivers/gpu/drm/bridge/ti-sn65dsi83.c:436:13: warning: incorrect type in assignment (different base types)
drivers/gpu/drm/bridge/ti-sn65dsi83.c:436:13: expected unsigned short [addressable] [assigned] [usertype] val
drivers/gpu/drm/bridge/ti-sn65dsi83.c:436:13: got restricted __le16 [usertype]
drivers/gpu/drm/bridge/ti-sn65dsi83.c:438:13: warning: incorrect type in assignment (different base types)
drivers/gpu/drm/bridge/ti-sn65dsi83.c:438:13: expected unsigned short [addressable] [assigned] [usertype] val
drivers/gpu/drm/bridge/ti-sn65dsi83.c:438:13: got restricted __le16 [usertype]
drivers/gpu/drm/bridge/ti-sn65dsi83.c:441:13: warning: incorrect type in assignment (different base types)
drivers/gpu/drm/bridge/ti-sn65dsi83.c:441:13: expected unsigned short [addressable] [assigned] [usertype] val
drivers/gpu/drm/bridge/ti-sn65dsi83.c:441:13: got restricted __le16 [usertype]
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Adam Ford <aford173@gmail.com>
Cc: Douglas Anderson <dianders@chromium.org>
Cc: Frieder Schrempf <frieder.schrempf@kontron.de>
Cc: Jagan Teki <jagan@amarulasolutions.com>
Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Loic Poulain <loic.poulain@linaro.org>
Cc: Marek Vasut <marex@denx.de>
Cc: Philippe Schenker <philippe.schenker@toradex.com>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Stephen Boyd <swboyd@chromium.org>
Cc: Valentin Raevsky <valentin@compulab.co.il>
To: dri-devel@lists.freedesktop.org
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210608142211.82333-1-marex@denx.de
Originally when using pm_runtime_put, there's a chance that the runtime
suspend hook will be run after the following anx7625_bridge_mode_set
call, resulting in the display_timing_valid field to be cleared, and the
following power on fail.
Change all pm_runtime_put to pm_runtime_put_sync, so all power off
operations are guaranteed to be done after the call returns.
Fixes: 60487584a7 ("drm/bridge: anx7625: refactor power control to use runtime PM framework")
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Tested-by: Tzung-Bi Shih <tzungbi@google.com>
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210520064508.3121211-1-pihsun@chromium.org
The ti_sn_aux_transfer() function returns ssize_t (signed long). It's
supposed to return negative error codes or the number of bytes
transferred. The "ret" variable is int and the "len" variable is
unsigned int.
The problem is that with a ternary like this, the negative int is first
type promoted to unsigned int to match "len" at this point it is a high
positive value. Then when it is type promoted to ssize_t (s64) it
remains a high positive value instead of sign extending and becoming a
negative again.
Fix this by removing the ternary.
Fixes: b137406d96 ("drm/bridge: ti-sn65dsi86: If refclk, DP AUX can happen w/out pre-enable")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/YKOGogHasIyvF8nj@mwanda
The driver originally use an atomic_t for keep track of the power
status, which makes the driver more complicated than needed, and has
some race condition as it's possible to have the power on and power off
sequence going at the same time.
This patch remove the usage of the atomic_t power_status, and use the
kernel runtime power management framework instead.
Signed-off-by: Pi-Hsun Shih <pihsun@chromium.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@google.com>
Signed-off-by: Robert Foss <robert.foss@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210517063553.554955-1-pihsun@chromium.org
Let's reorganize how we init and turn on the reference clock in the
code to allow us to turn it on early (even before pre_enable()) so
that we can read the EDID early. This is handy for eDP because:
- We always assume that a panel is there.
- Once we report that a panel is there we get asked to read the EDID.
- Pre-enable isn't called until we know what pixel clock we want to
use and we're ready to turn everything on. That's _after_ we get
asked to read the EDID.
NOTE: the above only works out OK if we "refclk" is provided. Though I
don't have access to any hardware that uses ti-sn65dsi86 and _doesn't_
provide a "refclk", I believe that we'll have trouble reading the EDID
at bootup in that case. Specifically I believe that if there's no
"refclk" we need the MIPI source clock to be active before we can
successfully read the EDID. My evidence here is that, in testing, I
couldn't read the EDID until I turned on the DPPLL in the bridge chip
and that the DPPLL needs the input clock to be active.
Since this is hard to support, let's punt trying to handle this case
if there's no "refclk". In that case we'll enable comms in
pre_enable() like we always did.
I don't believe there are any users of the ti-sn65dsi86 bridge chip
that _don't_ use "refclk". The bridge chip is _very_ inflexible in
that mode. The only time I've seen that mode used was for some really
early prototype hardware that was thrown in the e-waste bin years ago
when we realized how inflexible it was.
Even if someone is using the bridge chip without the "refclk" they're
in no worse shape than they were before the (fairly recent) commit
58074b08c0 ("drm/bridge: ti-sn65dsi86: Read EDID blob over DDC").
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.13.Ie8cf556114953c6e7634564cc0d3ddbd103cb96c@changeid
Let's use the newly minted aux bus to break up the driver into sub
drivers. We're not doing a full breakup here: all the code is still in
the same file and remains largely untouched. The big goal here of
using sub-drivers is to allow part of our code to finish probing even
if some other code needs to defer. This can solve some chicken-and-egg
problems. Specifically:
- In commit 48834e6084 ("drm/panel-simple: Support hpd-gpios for
delaying prepare()") we had to add a bit of a hack to simpel-panel
to support HPD showing up late. We can get rid of that hack now
since the GPIO part of our driver can finish probing early.
- We have a desire to expose our DDC bus to simple-panel (and perhaps
to a backlight driver?). That will end up with the same
chicken-and-egg problem. A future patch to move this to a sub-driver
will fix it.
- If/when we support the PWM functionality present in the bridge chip
for a backlight we'll end up with another chicken-and-egg
problem. If we allow the PWM to be a sub-driver too then it solves
this problem.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423095743.v5.9.I3e68fa38c4ccbdbdf145cad2b01e83a1e5eac302@changeid
This is something that we've wanted for a while now: the ability to
actually look up the respective drm_device for a given drm_dp_aux struct.
This will also allow us to transition over to using the drm_dbg_*() helpers
for debug message printing, as we'll finally have a drm_device to reference
for doing so.
Note that there is one limitation with this - because some DP AUX adapters
exist as platform devices which are initialized independently of their
respective DRM devices, one cannot rely on drm_dp_aux->drm_dev to always be
non-NULL until drm_dp_aux_register() has been called. We make sure to point
this out in the documentation for struct drm_dp_aux.
v3:
* Add WARN_ON_ONCE() to drm_dp_aux_register() if drm_dev isn't filled out
Signed-off-by: Lyude Paul <lyude@redhat.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210423184309.207645-4-lyude@redhat.com
Reviewed-by: Dave Airlie <airlied@redhat.com>
