Re: [PATCH 3/8] drm: Add drm_for_each_connector_encoder_ids()

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Jun 26, 2018 at 08:47:09PM +0300, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> Add a convenience macro for iterating connector->encoder_ids[].
> Isolates the users from the implementation details.
> 
> Also use ARRAY_SIZE() when populating the array to avoid spreading
> knowledge about the array size all over.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/drm_connector.c    | 22 ++++++++++------------
>  drivers/gpu/drm/drm_fb_helper.c    |  6 +++---
>  drivers/gpu/drm/drm_probe_helper.c |  9 +++++----
>  include/drm/drm_connector.h        | 11 +++++++++++
>  4 files changed, 29 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_connector.c b/drivers/gpu/drm/drm_connector.c
> index 2f9ebddd178e..c43646cb8145 100644
> --- a/drivers/gpu/drm/drm_connector.c
> +++ b/drivers/gpu/drm/drm_connector.c
> @@ -321,7 +321,7 @@ int drm_mode_connector_attach_encoder(struct drm_connector *connector,
>  	if (WARN_ON(connector->encoder))
>  		return -EINVAL;
>  
> -	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> +	for (i = 0; i < ARRAY_SIZE(connector->encoder_ids); i++) {
>  		if (connector->encoder_ids[i] == 0) {
>  			connector->encoder_ids[i] = encoder->base.id;
>  			return 0;
> @@ -1693,6 +1693,7 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>  	int encoders_count = 0;
>  	int ret = 0;
>  	int copied = 0;
> +	u32 encoder_id;
>  	int i;
>  	struct drm_mode_modeinfo u_mode;
>  	struct drm_mode_modeinfo __user *mode_ptr;
> @@ -1708,22 +1709,19 @@ int drm_mode_getconnector(struct drm_device *dev, void *data,
>  	if (!connector)
>  		return -ENOENT;
>  
> -	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++)
> -		if (connector->encoder_ids[i] != 0)
> -			encoders_count++;
> +	drm_for_each_connector_encoder_ids(connector, encoder_id, i)
> +		encoders_count++;
>  
>  	if ((out_resp->count_encoders >= encoders_count) && encoders_count) {
>  		copied = 0;
>  		encoder_ptr = (uint32_t __user *)(unsigned long)(out_resp->encoders_ptr);
> -		for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> -			if (connector->encoder_ids[i] != 0) {
> -				if (put_user(connector->encoder_ids[i],
> -					     encoder_ptr + copied)) {
> -					ret = -EFAULT;
> -					goto out;
> -				}
> -				copied++;
> +
> +		drm_for_each_connector_encoder_ids(connector, encoder_id, i) {
> +			if (put_user(encoder_id, encoder_ptr + copied)) {
> +				ret = -EFAULT;
> +				goto out;
>  			}
> +			copied++;
>  		}
>  	}
>  	out_resp->count_encoders = encoders_count;
> diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
> index 61c39cd75a27..e086b08748f4 100644
> --- a/drivers/gpu/drm/drm_fb_helper.c
> +++ b/drivers/gpu/drm/drm_fb_helper.c
> @@ -2326,12 +2326,12 @@ static bool drm_target_preferred(struct drm_fb_helper *fb_helper,
>  static bool connector_crtc_ok(struct drm_connector *connector,
>  			      struct drm_crtc *crtc)
>  {
> +	u32 encoder_id;
>  	int i;
>  
> -	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> +	drm_for_each_connector_encoder_ids(connector, encoder_id, i) {
>  		struct drm_encoder *encoder =
> -			drm_encoder_find(connector->dev, NULL,
> -					 connector->encoder_ids[i]);
> +			drm_encoder_find(connector->dev, NULL, encoder_id);
>  
>  		if (encoder->possible_crtcs & drm_crtc_mask(crtc))
>  			return true;
> diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
> index 527743394150..0239f76c52fb 100644
> --- a/drivers/gpu/drm/drm_probe_helper.c
> +++ b/drivers/gpu/drm/drm_probe_helper.c
> @@ -88,9 +88,9 @@ drm_mode_validate_pipeline(struct drm_display_mode *mode,
>  			    struct drm_connector *connector)
>  {
>  	struct drm_device *dev = connector->dev;
> -	uint32_t *ids = connector->encoder_ids;
>  	enum drm_mode_status ret = MODE_OK;
> -	unsigned int i;
> +	u32 encoder_id;
> +	int i;
>  
>  	/* Step 1: Validate against connector */
>  	ret = drm_connector_mode_valid(connector, mode);
> @@ -98,8 +98,9 @@ drm_mode_validate_pipeline(struct drm_display_mode *mode,
>  		return ret;
>  
>  	/* Step 2: Validate against encoders and crtcs */
> -	for (i = 0; i < DRM_CONNECTOR_MAX_ENCODER; i++) {
> -		struct drm_encoder *encoder = drm_encoder_find(dev, NULL, ids[i]);
> +	drm_for_each_connector_encoder_ids(connector, encoder_id, i) {
> +		struct drm_encoder *encoder =
> +			drm_encoder_find(dev, NULL, encoder_id);
>  		struct drm_crtc *crtc;
>  
>  		if (!encoder)
> diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h
> index 14ab58ade87f..4a0363f7dd8c 100644
> --- a/include/drm/drm_connector.h
> +++ b/include/drm/drm_connector.h
> @@ -1193,4 +1193,15 @@ void drm_connector_list_iter_end(struct drm_connector_list_iter *iter);
>  #define drm_for_each_connector_iter(connector, iter) \
>  	while ((connector = drm_connector_list_iter_next(iter)))
>  
> +/**
> + * drm_for_each_connector_encoder_ids - iterate connector encoder_ids[]

&drm_connector.encoder_ids would give you a (fairly direct) link. Just a
nitpick.

Wrt the api: I think including the drm_encoder_find would be useful here -
it's what 2/3 users want anyway, and the ioctl can easily look up the id
again by following encoder->base.id. And then maybe call the function a
bit differently, I think usually we go with
$parent_object_for_each_$iterated_thing, so
drm_connector_for_each_encoder(). There's also the
for_each_$thing_in_$parent_object pattern (used for atomic states), but I
think that's less fitting here.

Apologies for the interface bikeshedding ...
-Daniel

> + * @connector: &struct drm_connector pointer used as cursor
> + * @encoder_id: the encoder ID
> + * @__i: int iteration cursor, for macro-internal use
> + */
> +#define drm_for_each_connector_encoder_ids(connector, encoder_id, __i) \
> +	for ((__i) = 0; (__i) < ARRAY_SIZE((connector)->encoder_ids) && \
> +		     (connector)->encoder_ids[(__i)] != 0; (__i)++) \
> +		for_each_if((encoder_id) = (connector)->encoder_ids[(__i)])
> +
>  #endif
> -- 
> 2.16.4
> 
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> dri-devel@lists.freedesktop.org
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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