Re: [PATCH v2 05/21] drm: Minimally initialise drm_dp_aux

[Daniel Vetter <daniel@ffwll.ch>]

On Mon, May 30, 2016 at 09:38:23AM +0100, Chris Wilson wrote:
> When trying to split up the initialisation phase and the registration
> phase, one immediate problem encountered is trying to use our own i2c
> devices before registration with userspace. drm_dp_aux in particular
> only offers an interface for setting up the device after we have exposed
> the connector via sysfs. In order to break the chicken-and-egg problem,
> export drm_dp_aux_init() to minimally prepare the i2c device for
> internal use before drm_connector_register().
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Rafael Antognolli <rafael.antognolli@intel.com>
> Cc: dri-devel@lists.freedesktop.org
> ---
>  drivers/gpu/drm/drm_dp_helper.c | 18 +++++++++++++-----
>  include/drm/drm_dp_helper.h     |  1 +
>  2 files changed, 14 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index eeaf5a7c3aa7..e1900d386685 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -774,6 +774,17 @@ static const struct i2c_algorithm drm_dp_i2c_algo = {
>  	.master_xfer = drm_dp_i2c_xfer,
>  };
>  
> +void drm_dp_aux_init(struct drm_dp_aux *aux)

Needs kerneldoc. Pleas also cross-reference to drm_dp_aux_register. Didn't
read all the i2c code to make sure stuff really works with just that, but
makes sense.

All three core patches also need an ack from Dave.
-Daniel

> +{
> +	mutex_init(&aux->hw_mutex);
> +	rt_mutex_init(&aux->ddc.bus_lock);
> +
> +	aux->ddc.algo = &drm_dp_i2c_algo;
> +	aux->ddc.algo_data = aux;
> +	aux->ddc.retries = 3;
> +}
> +EXPORT_SYMBOL(drm_dp_aux_init);
> +
>  /**
>   * drm_dp_aux_register() - initialise and register aux channel
>   * @aux: DisplayPort AUX channel
> @@ -784,11 +795,8 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
>  {
>  	int ret;
>  
> -	mutex_init(&aux->hw_mutex);
> -
> -	aux->ddc.algo = &drm_dp_i2c_algo;
> -	aux->ddc.algo_data = aux;
> -	aux->ddc.retries = 3;
> +	if (!aux->ddc.algo)
> +		drm_dp_aux_init(aux);
>  
>  	aux->ddc.class = I2C_CLASS_DDC;
>  	aux->ddc.owner = THIS_MODULE;
> diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
> index 5a848e734422..4d85cf2874af 100644
> --- a/include/drm/drm_dp_helper.h
> +++ b/include/drm/drm_dp_helper.h
> @@ -805,6 +805,7 @@ int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_power_down(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link);
>  
> +void drm_dp_aux_init(struct drm_dp_aux *aux);
>  int drm_dp_aux_register(struct drm_dp_aux *aux);
>  void drm_dp_aux_unregister(struct drm_dp_aux *aux);
>  
> -- 
> 2.8.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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