diff options
Diffstat (limited to 'board/chromebook/elm/patches/linux/0005-drm-bridge-ps8640-Rework-power-state-handling.patch')
| -rw-r--r-- | board/chromebook/elm/patches/linux/0005-drm-bridge-ps8640-Rework-power-state-handling.patch | 162 |
1 files changed, 162 insertions, 0 deletions
diff --git a/board/chromebook/elm/patches/linux/0005-drm-bridge-ps8640-Rework-power-state-handling.patch b/board/chromebook/elm/patches/linux/0005-drm-bridge-ps8640-Rework-power-state-handling.patch new file mode 100644 index 0000000000..f682600d11 --- /dev/null +++ b/board/chromebook/elm/patches/linux/0005-drm-bridge-ps8640-Rework-power-state-handling.patch @@ -0,0 +1,162 @@ +From 5bb60fe7c748a0aae2bdbab10e73b2dc48c09dda Mon Sep 17 00:00:00 2001 +From: Enric Balletbo i Serra <enric.balletbo@collabora.com> +Date: Wed, 26 Aug 2020 10:15:26 +0200 +Subject: [PATCH 5/5] drm/bridge: ps8640: Rework power state handling + +The get_edid() callback can be triggered anytime by an ioctl, i.e + + drm_mode_getconnector (ioctl) + -> drm_helper_probe_single_connector_modes + -> drm_bridge_connector_get_modes + -> ps8640_bridge_get_edid + +Actually if the bridge pre_enable() function was not called before +get_edid(), the driver will not be able to get the EDID properly and +display will not work until a second get_edid() call is issued and if +pre_enable() is called before. The side effect of this, for example, is +that you see anything when `Frecon` starts, neither the splash screen, +until the graphical session manager starts. + +To fix this we need to make sure that all we need is enabled before +reading the EDID. This means the following: + +1. If get_edid() is called before having the device powered we need to + power on the device. In such case, the driver will power off again the + device. + +2. If get_edid() is called after having the device powered, all should + just work. We added a powered flag in order to avoid recurrent calls + to ps8640_bridge_poweron() and unneeded delays. + +3. This seems to be specific for this device, but we need to make sure + the panel is powered on before do a power on cycle on this device. + Otherwise the device fails to retrieve the EDID. + +Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com> +--- + drivers/gpu/drm/bridge/parade-ps8640.c | 64 +++++++++++++++++++++++--- + 1 file changed, 58 insertions(+), 6 deletions(-) + +diff --git a/drivers/gpu/drm/bridge/parade-ps8640.c b/drivers/gpu/drm/bridge/parade-ps8640.c +index 9f7b7a9c53c5..c5d76e209bda 100644 +--- a/drivers/gpu/drm/bridge/parade-ps8640.c ++++ b/drivers/gpu/drm/bridge/parade-ps8640.c +@@ -65,6 +65,7 @@ struct ps8640 { + struct regulator_bulk_data supplies[2]; + struct gpio_desc *gpio_reset; + struct gpio_desc *gpio_powerdown; ++ bool powered; + }; + + static inline struct ps8640 *bridge_to_ps8640(struct drm_bridge *e) +@@ -91,13 +92,15 @@ static int ps8640_bridge_vdo_control(struct ps8640 *ps_bridge, + return 0; + } + +-static void ps8640_pre_enable(struct drm_bridge *bridge) ++static void ps8640_bridge_poweron(struct ps8640 *ps_bridge) + { +- struct ps8640 *ps_bridge = bridge_to_ps8640(bridge); + struct i2c_client *client = ps_bridge->page[PAGE2_TOP_CNTL]; + unsigned long timeout; + int ret, status; + ++ if (ps_bridge->powered) ++ return; ++ + ret = regulator_bulk_enable(ARRAY_SIZE(ps_bridge->supplies), + ps_bridge->supplies); + if (ret < 0) { +@@ -164,6 +167,8 @@ static void ps8640_pre_enable(struct drm_bridge *bridge) + goto err_regulators_disable; + } + ++ ps_bridge->powered = true; ++ + return; + + err_regulators_disable: +@@ -171,12 +176,12 @@ static void ps8640_pre_enable(struct drm_bridge *bridge) + ps_bridge->supplies); + } + +-static void ps8640_post_disable(struct drm_bridge *bridge) ++static void ps8640_bridge_poweroff(struct ps8640 *ps_bridge) + { +- struct ps8640 *ps_bridge = bridge_to_ps8640(bridge); + int ret; + +- ps8640_bridge_vdo_control(ps_bridge, DISABLE); ++ if (!ps_bridge->powered) ++ return; + + gpiod_set_value(ps_bridge->gpio_reset, 1); + gpiod_set_value(ps_bridge->gpio_powerdown, 1); +@@ -184,6 +189,28 @@ static void ps8640_post_disable(struct drm_bridge *bridge) + ps_bridge->supplies); + if (ret < 0) + DRM_ERROR("cannot disable regulators %d\n", ret); ++ ++ ps_bridge->powered = false; ++} ++ ++static void ps8640_pre_enable(struct drm_bridge *bridge) ++{ ++ struct ps8640 *ps_bridge = bridge_to_ps8640(bridge); ++ int ret; ++ ++ ps8640_bridge_poweron(ps_bridge); ++ ++ ret = ps8640_bridge_vdo_control(ps_bridge, DISABLE); ++ if (ret < 0) ++ ps8640_bridge_poweroff(ps_bridge); ++} ++ ++static void ps8640_post_disable(struct drm_bridge *bridge) ++{ ++ struct ps8640 *ps_bridge = bridge_to_ps8640(bridge); ++ ++ ps8640_bridge_vdo_control(ps_bridge, DISABLE); ++ ps8640_bridge_poweroff(ps_bridge); + } + + static int ps8640_bridge_attach(struct drm_bridge *bridge, +@@ -249,9 +276,34 @@ static struct edid *ps8640_bridge_get_edid(struct drm_bridge *bridge, + struct drm_connector *connector) + { + struct ps8640 *ps_bridge = bridge_to_ps8640(bridge); ++ bool poweroff = !ps_bridge->powered; ++ struct edid *edid; ++ ++ /* ++ * When we end calling get_edid() triggered by an ioctl, i.e ++ * ++ * drm_mode_getconnector (ioctl) ++ * -> drm_helper_probe_single_connector_modes ++ * -> drm_bridge_connector_get_modes ++ * -> ps8640_bridge_get_edid ++ * ++ * We need to make sure that what we need is enabled before reading ++ * EDID, for this chip, we need to do a full poweron, otherwise it will ++ * fail. ++ */ ++ drm_bridge_chain_pre_enable(bridge); + +- return drm_get_edid(connector, ++ edid = drm_get_edid(connector, + ps_bridge->page[PAGE0_DP_CNTL]->adapter); ++ ++ /* ++ * If we call the get_edid() function without having enabled the chip ++ * before, return the chip to its original power state. ++ */ ++ if (poweroff) ++ drm_bridge_chain_post_disable(bridge); ++ ++ return edid; + } + + static const struct drm_bridge_funcs ps8640_bridge_funcs = { +-- +2.25.1 + |