| Message ID | 20200826081526.674866-6-enric.balletbo@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/bridge: ps8640: Make sure all needed is powered to get the EDID | expand |
On Wed, 26 Aug 2020 10:15:26 +0200 Enric Balletbo i Serra <enric.balletbo@collabora.com> wrote: > 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> > --- > > Changes in v2: > - Use drm_bridge_chain_pre_enable/post_disable() helpers (Sam > Ravnborg) > > 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); Is it safe for a bridge driver to enable power to other devices in the bridge? Seems somewhat counter-intuitive, though I understand that the complete chain needs to be enabled before getting EDID in this case. Can we consider a more generic solution where the DRM stack enables the bridge-chain before invoking calls to get EDID based on a DT-binding or Kconfig option? Also shouldn't the call to pre_enable be followed by a call to "drm_bridge_chain_enable"? Similarly we should do both drm_bridge_chain_post_disable / *_disable when powering the chips off, right? > > - 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 = { -Bilal
Hi Sam, Thanks for your comments. On 26/8/20 20:46, Sam Ravnborg wrote: > Hi Enric. > > On Wed, Aug 26, 2020 at 10:15:26AM +0200, Enric Balletbo i Serra wrote: >> 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> >> --- >> >> Changes in v2: >> - Use drm_bridge_chain_pre_enable/post_disable() helpers (Sam Ravnborg) >> >> 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); >> +} > > The impleimentation of ps8640_bridge_poweron() versus > ps8640_bridge_poweroff() is confusing. > > ps8640_bridge_poweron() includes ps8640_bridge_vdo_control(.., ENABLE), > but ps8640_bridge_poweroff() does not include > ps8640_bridge_vdo_control(..., DISABLE). > > This is inconsistent and confusing. At least it was for me when > reviewing. Can this be improved - or maybe just use naming that does not > indicate they are the reverse of each other? > Right, I think I can implement reverse of each other. So I'll send an updated series. Thanks, Enric >> + >> +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; >> } > > The use of drm_bridge_chain_pre_enable() and > drm_bridge_chain_post_disable() was exactly what I was asking for - > looks good. > > I have not really considered the idea from Balil that we should provide > better infrastructure support powering on the bridge chain when reading > the edid. Maybe an idea for later? > > Sam > > > >> >> static const struct drm_bridge_funcs ps8640_bridge_funcs = { >> -- >> 2.28.0 >
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 = {
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> --- Changes in v2: - Use drm_bridge_chain_pre_enable/post_disable() helpers (Sam Ravnborg) drivers/gpu/drm/bridge/parade-ps8640.c | 64 +++++++++++++++++++++++--- 1 file changed, 58 insertions(+), 6 deletions(-)