Re: [Intel-gfx] [PATCH v8 1/2] drm/dp: Add a drm_aux-dev module for reading/writing dpcd registers.

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Nov 02, 2015 at 12:33:47PM -0800, Rafael Antognolli wrote:
<snip>
> +static int __init drm_dp_aux_dev_init(void)
> +{
> +	int res;
> +
> +	drm_dp_aux_dev_class = class_create(THIS_MODULE, "drm_dp_aux_dev");
> +	if (IS_ERR(drm_dp_aux_dev_class)) {
> +		res = PTR_ERR(drm_dp_aux_dev_class);
> +		goto out;
> +	}
> +	drm_dp_aux_dev_class->dev_groups = drm_dp_aux_groups;
> +
> +	res = register_chrdev(0, "aux", &auxdev_fops);
> +	if (res < 0)
> +		goto out;
> +	drm_dev_major = res;
> +
> +	return 0;
> +out:
> +	class_destroy(drm_dp_aux_dev_class);
> +	return res;
> +}
> +
> +static void __exit drm_dp_aux_dev_exit(void)
> +{
> +	unregister_chrdev(drm_dev_major, "aux");
> +	class_destroy(drm_dp_aux_dev_class);
> +}
> +
> +MODULE_AUTHOR("Rafael Antognolli <rafael.antognolli@intel.com>");
> +MODULE_DESCRIPTION("DRM DP AUX /dev entries driver");
> +MODULE_LICENSE("GPL and additional rights");
> +
> +module_init(drm_dp_aux_dev_init);
> +module_exit(drm_dp_aux_dev_exit);

Since this is no longer a separate module this stuff can cause a
build failure due to drm_fb_helper.c already providing a module_init
for the same module.

So maybe we neet to have module_init/exit for drm_kms_helper.o in
some central place and have those call the init/exit functions for
drm_fb_helper and drm_dp_aux_dev?

> diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
> index 9535c5b..7d58f59 100644
> --- a/drivers/gpu/drm/drm_dp_helper.c
> +++ b/drivers/gpu/drm/drm_dp_helper.c
> @@ -28,6 +28,7 @@
>  #include <linux/sched.h>
>  #include <linux/i2c.h>
>  #include <drm/drm_dp_helper.h>
> +#include <drm/drm_dp_aux_dev.h>
>  #include <drm/drmP.h>
>  
>  /**
> @@ -754,6 +755,8 @@ static const struct i2c_algorithm drm_dp_i2c_algo = {
>   */
>  int drm_dp_aux_register(struct drm_dp_aux *aux)
>  {
> +	int ret;
> +
>  	mutex_init(&aux->hw_mutex);
>  
>  	aux->ddc.algo = &drm_dp_i2c_algo;
> @@ -768,7 +771,17 @@ int drm_dp_aux_register(struct drm_dp_aux *aux)
>  	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(aux->dev),
>  		sizeof(aux->ddc.name));
>  
> -	return i2c_add_adapter(&aux->ddc);
> +	ret = drm_dp_aux_register_devnode(aux);
> +	if (ret)
> +		return ret;
> +
> +	ret = i2c_add_adapter(&aux->ddc);
> +	if (ret) {
> +		drm_dp_aux_unregister_devnode(aux);
> +		return ret;
> +	}
> +
> +	return 0;
>  }
>  EXPORT_SYMBOL(drm_dp_aux_register);
>  
> @@ -778,6 +791,7 @@ EXPORT_SYMBOL(drm_dp_aux_register);
>   */
>  void drm_dp_aux_unregister(struct drm_dp_aux *aux)
>  {
> +	drm_dp_aux_unregister_devnode(aux);
>  	i2c_del_adapter(&aux->ddc);
>  }
>  EXPORT_SYMBOL(drm_dp_aux_unregister);
> diff --git a/include/drm/drm_dp_aux_dev.h b/include/drm/drm_dp_aux_dev.h
> new file mode 100644
> index 0000000..391a2cf
> --- /dev/null
> +++ b/include/drm/drm_dp_aux_dev.h
> @@ -0,0 +1,50 @@
> +/*
> + * Copyright © 2015 Intel Corporation
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a
> + * copy of this software and associated documentation files (the "Software"),
> + * to deal in the Software without restriction, including without limitation
> + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> + * and/or sell copies of the Software, and to permit persons to whom the
> + * Software is furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice (including the next
> + * paragraph) shall be included in all copies or substantial portions of the
> + * Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> + * IN THE SOFTWARE.
> + *
> + * Authors:
> + *    Rafael Antognolli <rafael.antognolli@intel.com>
> + *
> + */
> +
> +#ifndef DRM_DP_AUX_DEV
> +#define DRM_DP_AUX_DEV
> +
> +#ifdef CONFIG_DRM_DP_AUX_CHARDEV
> +
> +int drm_dp_aux_register_devnode(struct drm_dp_aux *aux);
> +void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux);
> +
> +#else
> +
> +static inline int drm_dp_aux_register_devnode(struct drm_dp_aux *aux)
> +{
> +	return 0;
> +}
> +
> +static inline void drm_dp_aux_unregister_devnode(struct drm_dp_aux *aux)
> +{
> +	return 0;
> +}
> +
> +#endif
> +
> +#endif
> -- 
> 2.4.3
> 
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-- 
Ville Syrjälä
Intel OTC
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