Re: [RFC PATCH 03/10] drm/mipi-dsi: add API for manual control over the DSI link power state

[Maxime Ripard]

On Mon, Oct 16, 2023 at 07:53:48PM +0300, Dmitry Baryshkov wrote:
> The MIPI DSI links do not fully fall into the DRM callbacks model.

Explaining why would help

> The drm_bridge_funcs abstraction.

Is there a typo or missing words?

> 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@xxxxxxxxxx>
> ---
>  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);
> +

If this API is supposed to be used by DSI devices, it should probably
take a mipi_dsi_device pointer as a parameter?

We should probably make sure it hasn't been powered on already too?

Maxime