Messages in this thread | | | Date | Mon, 23 Oct 2023 09:35:04 +0200 | From | Neil Armstrong <> | Subject | Re: [RFC PATCH 03/10] drm/mipi-dsi: add API for manual control over the DSI link power state |
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On 16/10/2023 18:53, Dmitry Baryshkov wrote: > The MIPI DSI links do not fully fall into the DRM callbacks model. The > drm_bridge_funcs abstraction. Instead of having just two states (off and > on) the DSI hosts have separate LP-11 state. In this state the host is > on, but the video stream is not yet enabled. > > Introduce API that allows DSI bridges / panels to control the DSI host > power up state. > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org> > --- > drivers/gpu/drm/drm_mipi_dsi.c | 31 +++++++++++++++++++++++++++++++ > include/drm/drm_mipi_dsi.h | 29 +++++++++++++++++++++++++---- > 2 files changed, 56 insertions(+), 4 deletions(-) > > diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c > index 14201f73aab1..c467162cb7d8 100644 > --- a/drivers/gpu/drm/drm_mipi_dsi.c > +++ b/drivers/gpu/drm/drm_mipi_dsi.c > @@ -428,6 +428,37 @@ int devm_mipi_dsi_attach(struct device *dev, > } > EXPORT_SYMBOL_GPL(devm_mipi_dsi_attach); > > +bool mipi_dsi_host_power_control_available(struct mipi_dsi_host *host) > +{ > + const struct mipi_dsi_host_ops *ops = host->ops; > + > + return ops && ops->power_up; > +} > +EXPORT_SYMBOL_GPL(mipi_dsi_host_power_control_available); > + > +int mipi_dsi_host_power_up(struct mipi_dsi_host *host) > +{ > + const struct mipi_dsi_host_ops *ops = host->ops; > + > + if (!mipi_dsi_host_power_control_available(host)) > + return -EOPNOTSUPP; > + > + return ops->power_up ? ops->power_up(host) : 0; > +} > +EXPORT_SYMBOL_GPL(mipi_dsi_host_power_up); > + > +void mipi_dsi_host_power_down(struct mipi_dsi_host *host) > +{ > + const struct mipi_dsi_host_ops *ops = host->ops; > + > + if (!mipi_dsi_host_power_control_available(host)) > + return; > + > + if (ops->power_down) > + ops->power_down(host); > +} > +EXPORT_SYMBOL_GPL(mipi_dsi_host_power_down); > + > static ssize_t mipi_dsi_device_transfer(struct mipi_dsi_device *dsi, > struct mipi_dsi_msg *msg) > { > diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h > index 167742e579e3..e503c3e4d057 100644 > --- a/include/drm/drm_mipi_dsi.h > +++ b/include/drm/drm_mipi_dsi.h > @@ -68,6 +68,8 @@ int mipi_dsi_create_packet(struct mipi_dsi_packet *packet, > * @attach: attach DSI device to DSI host > * @detach: detach DSI device from DSI host > * @transfer: transmit a DSI packet > + * @power_up: enable DSI link and bring it to the LP-11 state > + * @power_down: fully disable DSI link > * > * DSI packets transmitted by .transfer() are passed in as mipi_dsi_msg > * structures. This structure contains information about the type of packet > @@ -81,10 +83,18 @@ int mipi_dsi_create_packet(struct mipi_dsi_packet *packet, > * function will seldomly return anything other than the number of bytes > * contained in the transmit buffer on success. > * > - * Also note that those callbacks can be called no matter the state the > - * host is in. Drivers that need the underlying device to be powered to > - * perform these operations will first need to make sure it's been > - * properly enabled. > + * Note: currently there are two modes of DSI power control. Legacy drivers > + * will call those callbacks no matter the state the host is in. DSI host > + * drivers that need the underlying device to be powered to perform these > + * operations will first need to make sure it's been properly enabled. > + * > + * Newer drivers will set the @MIPI_DSI_MANUAL_POWERUP flag to indicate that > + * they will call @mipi_dsi_power_up() and @mipi_dsi_power_down() to control > + * the link state of the DSI host or they will set @MIPI_DSI_AUTO_POWERUP to > + * indicate that the driver is fine with the link being powered up in DSI > + * host's (atomic_)pre_enable() callback and then being disabled in the > + * (atomic_)post_disable() callback. The transfer callback must only be called > + * if the DSI host has been powered up and was not brought down. > * > * Note: some hosts (sunxi) can not send LP commands between HS video > * packets. Thus all DSI transfers sent in LP mode should be limited to the > @@ -97,6 +107,8 @@ struct mipi_dsi_host_ops { > struct mipi_dsi_device *dsi); > ssize_t (*transfer)(struct mipi_dsi_host *host, > const struct mipi_dsi_msg *msg); > + int (*power_up)(struct mipi_dsi_host *host); > + void (*power_down)(struct mipi_dsi_host *host); > }; > > /** > @@ -143,6 +155,10 @@ struct mipi_dsi_host *of_find_mipi_dsi_host_by_node(struct device_node *node); > #define MIPI_DSI_MODE_LPM BIT(11) > /* transmit data ending at the same time for all lanes within one hsync */ > #define MIPI_DSI_HS_PKT_END_ALIGNED BIT(12) > +/* DSI peripheral driver manually controls DSI link powerup */ > +#define MIPI_DSI_MANUAL_POWERUP BIT(13) > +/* DSI peripheral driver is fine with automatic DSI link power control */ > +#define MIPI_DSI_AUTO_POWERUP BIT(14)
What happens if none of the bits are in the flags ?
Can't we implement "opportunistic power-up" on the first DSI command sent?
If a bridge/panel sends a DSI command, and if it happens before the DSI host enable, then the DSI host will "pre-enable" the host and put the link in LP-11.
This would be simpler and would work whatever the pre_enable order.
But this won't work for the tc358767, except if we add a dummy DSI host command which powers up the DSI link.
This won't fix the PS8640 either who also needs a disabled DSI link to initialize.
Neil
> > enum mipi_dsi_pixel_format { > MIPI_DSI_FMT_RGB888, > @@ -235,6 +251,11 @@ void mipi_dsi_device_unregister(struct mipi_dsi_device *dsi); > struct mipi_dsi_device * > devm_mipi_dsi_device_register_full(struct device *dev, struct mipi_dsi_host *host, > const struct mipi_dsi_device_info *info); > + > +bool mipi_dsi_host_power_control_available(struct mipi_dsi_host *host); > +int mipi_dsi_host_power_up(struct mipi_dsi_host *host); > +void mipi_dsi_host_power_down(struct mipi_dsi_host *host); > + > struct mipi_dsi_device *of_find_mipi_dsi_device_by_node(struct device_node *np); > int mipi_dsi_attach(struct mipi_dsi_device *dsi); > int mipi_dsi_detach(struct mipi_dsi_device *dsi);
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