[alsa-devel] [PATCH] ALSA: pcm: Mostly constify constraints

[Takashi Iwai]

At Wed,  4 Jul 2012 18:35:12 +0100,
Mark Brown wrote:
> 
> There is no need for the constraints to be modified while being
> applied

Many drivers pass the local instance to rule->private, and it's not
always guaranteed to be const.  For example, you can imagine some
state modified kept in the struct while it's modified via rules.

In short: you'd have seen many compile warnings for non-ASoC drivers
if you run make once with this patch ;)

As a safe side fix, how about just adding const to
snd_pcm_hw_constraint_list() & co, and expclitly cast to non-const
later?


Takashi

> so
> they can be declared const, allowing drivers to declare constraint lists
> const if they wish.
> 
> Signed-off-by: Mark Brown <broonie at opensource.wolfsonmicro.com>
> ---
>  include/sound/pcm.h     |    6 +++---
>  sound/core/pcm_lib.c    |   10 +++++-----
>  sound/core/pcm_native.c |    4 ++--
>  3 files changed, 10 insertions(+), 10 deletions(-)
> 
> diff --git a/include/sound/pcm.h b/include/sound/pcm.h
> index e7afcc9..3b8f6ca 100644
> --- a/include/sound/pcm.h
> +++ b/include/sound/pcm.h
> @@ -217,7 +217,7 @@ struct snd_pcm_hw_rule {
>  	snd_pcm_hw_rule_func_t func;
>  	int var;
>  	int deps[4];
> -	void *private;
> +	const void *private;
>  };
>  
>  struct snd_pcm_hw_constraints {
> @@ -810,7 +810,7 @@ int snd_pcm_hw_constraint_integer(struct snd_pcm_runtime *runtime, snd_pcm_hw_pa
>  int snd_pcm_hw_constraint_list(struct snd_pcm_runtime *runtime, 
>  			       unsigned int cond,
>  			       snd_pcm_hw_param_t var,
> -			       struct snd_pcm_hw_constraint_list *l);
> +			       const struct snd_pcm_hw_constraint_list *l);
>  int snd_pcm_hw_constraint_ratnums(struct snd_pcm_runtime *runtime, 
>  				  unsigned int cond,
>  				  snd_pcm_hw_param_t var,
> @@ -835,7 +835,7 @@ int snd_pcm_hw_rule_noresample(struct snd_pcm_runtime *runtime,
>  int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime,
>  			unsigned int cond,
>  			int var,
> -			snd_pcm_hw_rule_func_t func, void *private,
> +			snd_pcm_hw_rule_func_t func, const void *private,
>  			int dep, ...);
>  
>  int snd_pcm_format_signed(snd_pcm_format_t format);
> diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
> index 8f312fa6..4372de5 100644
> --- a/sound/core/pcm_lib.c
> +++ b/sound/core/pcm_lib.c
> @@ -1104,7 +1104,7 @@ static int snd_interval_step(struct snd_interval *i, unsigned int min, unsigned
>   */
>  int snd_pcm_hw_rule_add(struct snd_pcm_runtime *runtime, unsigned int cond,
>  			int var,
> -			snd_pcm_hw_rule_func_t func, void *private,
> +			snd_pcm_hw_rule_func_t func, const void *private,
>  			int dep, ...)
>  {
>  	struct snd_pcm_hw_constraints *constrs = &runtime->hw_constraints;
> @@ -1233,7 +1233,7 @@ EXPORT_SYMBOL(snd_pcm_hw_constraint_minmax);
>  static int snd_pcm_hw_rule_list(struct snd_pcm_hw_params *params,
>  				struct snd_pcm_hw_rule *rule)
>  {
> -	struct snd_pcm_hw_constraint_list *list = rule->private;
> +	const struct snd_pcm_hw_constraint_list *list = rule->private;
>  	return snd_interval_list(hw_param_interval(params, rule->var), list->count, list->list, list->mask);
>  }		
>  
> @@ -1250,7 +1250,7 @@ static int snd_pcm_hw_rule_list(struct snd_pcm_hw_params *params,
>  int snd_pcm_hw_constraint_list(struct snd_pcm_runtime *runtime,
>  			       unsigned int cond,
>  			       snd_pcm_hw_param_t var,
> -			       struct snd_pcm_hw_constraint_list *l)
> +			       const struct snd_pcm_hw_constraint_list *l)
>  {
>  	return snd_pcm_hw_rule_add(runtime, cond, var,
>  				   snd_pcm_hw_rule_list, l,
> @@ -1262,7 +1262,7 @@ EXPORT_SYMBOL(snd_pcm_hw_constraint_list);
>  static int snd_pcm_hw_rule_ratnums(struct snd_pcm_hw_params *params,
>  				   struct snd_pcm_hw_rule *rule)
>  {
> -	struct snd_pcm_hw_constraint_ratnums *r = rule->private;
> +	const struct snd_pcm_hw_constraint_ratnums *r = rule->private;
>  	unsigned int num = 0, den = 0;
>  	int err;
>  	err = snd_interval_ratnum(hw_param_interval(params, rule->var),
> @@ -1296,7 +1296,7 @@ EXPORT_SYMBOL(snd_pcm_hw_constraint_ratnums);
>  static int snd_pcm_hw_rule_ratdens(struct snd_pcm_hw_params *params,
>  				   struct snd_pcm_hw_rule *rule)
>  {
> -	struct snd_pcm_hw_constraint_ratdens *r = rule->private;
> +	const struct snd_pcm_hw_constraint_ratdens *r = rule->private;
>  	unsigned int num = 0, den = 0;
>  	int err = snd_interval_ratden(hw_param_interval(params, rule->var),
>  				  r->nrats, r->rats, &num, &den);
> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
> index 53b5ada..5cc8c4f 100644
> --- a/sound/core/pcm_native.c
> +++ b/sound/core/pcm_native.c
> @@ -1775,7 +1775,7 @@ const struct snd_pcm_hw_constraint_list snd_pcm_known_rates = {
>  static int snd_pcm_hw_rule_rate(struct snd_pcm_hw_params *params,
>  				struct snd_pcm_hw_rule *rule)
>  {
> -	struct snd_pcm_hardware *hw = rule->private;
> +	const struct snd_pcm_hardware *hw = rule->private;
>  	return snd_interval_list(hw_param_interval(params, rule->var),
>  				 snd_pcm_known_rates.count,
>  				 snd_pcm_known_rates.list, hw->rates);
> @@ -1785,7 +1785,7 @@ static int snd_pcm_hw_rule_buffer_bytes_max(struct snd_pcm_hw_params *params,
>  					    struct snd_pcm_hw_rule *rule)
>  {
>  	struct snd_interval t;
> -	struct snd_pcm_substream *substream = rule->private;
> +	const struct snd_pcm_substream *substream = rule->private;
>  	t.min = 0;
>  	t.max = substream->buffer_bytes_max;
>  	t.openmin = 0;
> -- 
> 1.7.10
>