From: Douglas Anderson <dianders@chromium.org>
To: Jiri Kosina <jikos@kernel.org>,
Benjamin Tissoires <benjamin.tissoires@redhat.com>,
Bjorn Andersson <andersson@kernel.org>,
Konrad Dybcio <konrad.dybcio@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Frank Rowand <frowand.list@gmail.com>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Conor Dooley <conor+dt@kernel.org>,
Neil Armstrong <neil.armstrong@linaro.org>,
Sam Ravnborg <sam@ravnborg.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>
Cc: dri-devel@lists.freedesktop.org,
Dmitry Torokhov <dmitry.torokhov@gmail.com>,
linux-input@vger.kernel.org, Daniel Vetter <daniel@ffwll.ch>,
linux-kernel@vger.kernel.org, hsinyi@google.com,
cros-qcom-dts-watchers@chromium.org, devicetree@vger.kernel.org,
yangcong5@huaqin.corp-partner.google.com,
linux-arm-msm@vger.kernel.org,
Chris Morgan <macroalpha82@gmail.com>,
Douglas Anderson <dianders@chromium.org>
Subject: [PATCH v2 02/10] drm/panel: Check for already prepared/enabled in drm_panel
Date: Wed, 7 Jun 2023 14:49:24 -0700 [thread overview]
Message-ID: <20230607144931.v2.2.I59b417d4c29151cc2eff053369ec4822b606f375@changeid> (raw)
In-Reply-To: <20230607215224.2067679-1-dianders@chromium.org>
In a whole pile of panel drivers, we have code to make the
prepare/unprepare/enable/disable callbacks behave as no-ops if they've
already been called. It's silly to have this code duplicated
everywhere. Add it to the core instead so that we can eventually
delete it from all the drivers. Note: to get some idea of the
duplicated code, try:
git grep 'if.*>prepared' -- drivers/gpu/drm/panel
git grep 'if.*>enabled' -- drivers/gpu/drm/panel
NOTE: arguably, the right thing to do here is actually to skip this
patch and simply remove all the extra checks from the individual
drivers. Perhaps the checks were needed at some point in time in the
past but maybe they no longer are? Certainly as we continue
transitioning over to "panel_bridge" then we expect there to be much
less variety in how these calls are made. When we're called as part of
the bridge chain, things should be pretty simple. In fact, there was
some discussion in the past about these checks [1], including a
discussion about whether the checks were needed and whether the calls
ought to be refcounted. At the time, I decided not to mess with it
because it felt too risky.
Looking closer at it now, I'm fairly certain that nothing in the
existing codebase is expecting these calls to be refcounted. The only
real question is whether someone is already doing something to ensure
prepare()/unprepare() match and enabled()/disable() match. I would say
that, even if there is something else ensuring that things match,
there's enough complexity that adding an extra bool and an extra
double-check here is a good idea. Let's add a drm_warn() to let people
know that it's considered a minor error to take advantage of
drm_panel's double-checking but we'll still make things work fine.
[1] https://lore.kernel.org/r/20210416153909.v4.27.I502f2a92ddd36c3d28d014dd75e170c2d405a0a5@changeid
Acked-by: Neil Armstrong <neil.armstrong@linaro.org>
Signed-off-by: Douglas Anderson <dianders@chromium.org>
---
This has Neil's Ack and I could commit it to drm-misc-next, but for
now I'm holding off to see where this series ends up. If the series
ends up looking good we'll have to coordinate landing the various bits
between the drm and the hid trees and the second drm patch in my
series depends on this one.
If my series implodes I'll land this one on its own. In any case, once
this lands somewhere I'll take an AI to cleanup the panels.
(no changes since v1)
drivers/gpu/drm/drm_panel.c | 49 ++++++++++++++++++++++++++++++++-----
include/drm/drm_panel.h | 14 +++++++++++
2 files changed, 57 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_panel.c b/drivers/gpu/drm/drm_panel.c
index f634371c717a..4e1c4e42575b 100644
--- a/drivers/gpu/drm/drm_panel.c
+++ b/drivers/gpu/drm/drm_panel.c
@@ -105,11 +105,22 @@ EXPORT_SYMBOL(drm_panel_remove);
*/
int drm_panel_prepare(struct drm_panel *panel)
{
+ int ret;
+
if (!panel)
return -EINVAL;
- if (panel->funcs && panel->funcs->prepare)
- return panel->funcs->prepare(panel);
+ if (panel->prepared) {
+ dev_warn(panel->dev, "Skipping prepare of already prepared panel\n");
+ return 0;
+ }
+
+ if (panel->funcs && panel->funcs->prepare) {
+ ret = panel->funcs->prepare(panel);
+ if (ret < 0)
+ return ret;
+ }
+ panel->prepared = true;
return 0;
}
@@ -128,11 +139,22 @@ EXPORT_SYMBOL(drm_panel_prepare);
*/
int drm_panel_unprepare(struct drm_panel *panel)
{
+ int ret;
+
if (!panel)
return -EINVAL;
- if (panel->funcs && panel->funcs->unprepare)
- return panel->funcs->unprepare(panel);
+ if (!panel->prepared) {
+ dev_warn(panel->dev, "Skipping unprepare of already unprepared panel\n");
+ return 0;
+ }
+
+ if (panel->funcs && panel->funcs->unprepare) {
+ ret = panel->funcs->unprepare(panel);
+ if (ret < 0)
+ return ret;
+ }
+ panel->prepared = false;
return 0;
}
@@ -155,11 +177,17 @@ int drm_panel_enable(struct drm_panel *panel)
if (!panel)
return -EINVAL;
+ if (panel->enabled) {
+ dev_warn(panel->dev, "Skipping enable of already enabled panel\n");
+ return 0;
+ }
+
if (panel->funcs && panel->funcs->enable) {
ret = panel->funcs->enable(panel);
if (ret < 0)
return ret;
}
+ panel->enabled = true;
ret = backlight_enable(panel->backlight);
if (ret < 0)
@@ -187,13 +215,22 @@ int drm_panel_disable(struct drm_panel *panel)
if (!panel)
return -EINVAL;
+ if (!panel->enabled) {
+ dev_warn(panel->dev, "Skipping disable of already disabled panel\n");
+ return 0;
+ }
+
ret = backlight_disable(panel->backlight);
if (ret < 0)
DRM_DEV_INFO(panel->dev, "failed to disable backlight: %d\n",
ret);
- if (panel->funcs && panel->funcs->disable)
- return panel->funcs->disable(panel);
+ if (panel->funcs && panel->funcs->disable) {
+ ret = panel->funcs->disable(panel);
+ if (ret < 0)
+ return ret;
+ }
+ panel->enabled = false;
return 0;
}
diff --git a/include/drm/drm_panel.h b/include/drm/drm_panel.h
index 432fab2347eb..c6cf75909389 100644
--- a/include/drm/drm_panel.h
+++ b/include/drm/drm_panel.h
@@ -198,6 +198,20 @@ struct drm_panel {
* the panel is powered up.
*/
bool prepare_prev_first;
+
+ /**
+ * @prepared:
+ *
+ * If true then the panel has been prepared.
+ */
+ bool prepared;
+
+ /**
+ * @enabled:
+ *
+ * If true then the panel has been enabled.
+ */
+ bool enabled;
};
void drm_panel_init(struct drm_panel *panel, struct device *dev,
--
2.41.0.162.gfafddb0af9-goog
next prev parent reply other threads:[~2023-06-07 21:53 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-07 21:49 [PATCH v2 00/10] drm/panel and i2c-hid: Allow panels and touchscreens to power sequence together Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 01/10] dt-bindings: HID: i2c-hid: Add "panel" property to i2c-hid backed touchscreens Douglas Anderson
2023-06-09 15:53 ` Krzysztof Kozlowski
2023-06-07 21:49 ` Douglas Anderson [this message]
2023-06-07 21:49 ` [PATCH v2 03/10] drm/panel: Add a way for other devices to follow panel state Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 04/10] of: property: fw_devlink: Add a devlink for panel followers Douglas Anderson
2023-06-09 16:10 ` Rob Herring
2023-06-07 21:49 ` [PATCH v2 05/10] HID: i2c-hid: Switch to SYSTEM_SLEEP_PM_OPS() Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 06/10] HID: i2c-hid: Rearrange probe() to power things up later Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 07/10] HID: i2c-hid: Make suspend and resume into helper functions Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 08/10] HID: i2c-hid: Support being a panel follower Douglas Anderson
2023-06-08 5:18 ` kernel test robot
2023-06-08 7:14 ` kernel test robot
2023-06-08 15:10 ` Doug Anderson
2023-06-08 15:36 ` Benjamin Tissoires
2023-06-08 16:42 ` Doug Anderson
2023-06-09 9:27 ` Benjamin Tissoires
2023-06-09 15:01 ` Doug Anderson
2023-06-26 22:49 ` Doug Anderson
2023-07-17 18:15 ` Doug Anderson
2023-07-25 20:41 ` Doug Anderson
2023-07-26 8:07 ` Benjamin Tissoires
2023-06-07 21:49 ` [PATCH v2 09/10] HID: i2c-hid: Do panel follower work on the system_wq Douglas Anderson
2023-06-07 21:49 ` [PATCH v2 10/10] arm64: dts: qcom: sc7180: Link trogdor touchscreens to the panels Douglas Anderson
2023-06-08 7:17 ` [PATCH v2 00/10] drm/panel and i2c-hid: Allow panels and touchscreens to power sequence together Maxime Ripard
2023-06-08 14:38 ` Doug Anderson
2023-06-12 16:03 ` Maxime Ripard
2023-06-12 21:13 ` Doug Anderson
2023-06-13 12:06 ` Maxime Ripard
2023-06-13 15:56 ` Doug Anderson
2023-06-21 16:31 ` Doug Anderson
2023-06-23 9:08 ` Maxime Ripard
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