[RESEND PATCH v6 10/14] drm/print: Add drm_debug_category_printer

[abhinavk at codeaurora.org]

On 2021-07-21 10:55, Sean Paul wrote:
> From: Sean Paul <seanpaul at chromium.org>
> 
> This patch adds a new printer which will select the appropriate output
> for a given debug category. Currently there is only one output target,
> which is syslog. However in the future we'll have tracefs and it will 
> be
> useful to print to syslog, tracefs, or both. Drivers just need to 
> create
> the printer for the appropriate category and the printer will decide
> where to send the output.
> 
> Signed-off-by: Sean Paul <seanpaul at chromium.org>
Reviewed-by: Abhinav Kumar <abhinavk at codeaurora.org>
> Link:
> https://patchwork.freedesktop.org/patch/msgid/20200608210505.48519-11-sean@poorly.run
> #v5
> 
> Changes in v5:
> -Added to the set
> Changes in v6:
> -None
> ---
>  drivers/gpu/drm/drm_print.c |  5 +++++
>  include/drm/drm_print.h     | 28 ++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_print.c b/drivers/gpu/drm/drm_print.c
> index 2ff7a6ecc632..4d984a01b3a3 100644
> --- a/drivers/gpu/drm/drm_print.c
> +++ b/drivers/gpu/drm/drm_print.c
> @@ -172,6 +172,11 @@ void __drm_printfn_err(struct drm_printer *p,
> struct va_format *vaf)
>  }
>  EXPORT_SYMBOL(__drm_printfn_err);
> 
> +void __drm_printfn_noop(struct drm_printer *p, struct va_format *vaf)
> +{
> +}
> +EXPORT_SYMBOL(__drm_printfn_noop);
> +
>  /**
>   * drm_puts - print a const string to a &drm_printer stream
>   * @p: the &drm printer
> diff --git a/include/drm/drm_print.h b/include/drm/drm_print.h
> index 2ea0ffd9c1ce..af31beeb82a1 100644
> --- a/include/drm/drm_print.h
> +++ b/include/drm/drm_print.h
> @@ -87,6 +87,7 @@ void __drm_puts_seq_file(struct drm_printer *p,
> const char *str);
>  void __drm_printfn_info(struct drm_printer *p, struct va_format *vaf);
>  void __drm_printfn_debug_syslog(struct drm_printer *p, struct 
> va_format *vaf);
>  void __drm_printfn_err(struct drm_printer *p, struct va_format *vaf);
> +void __drm_printfn_noop(struct drm_printer *p, struct va_format *vaf);
> 
>  __printf(2, 3)
>  void drm_printf(struct drm_printer *p, const char *f, ...);
> @@ -329,6 +330,33 @@ static inline bool drm_debug_enabled(enum
> drm_debug_category category)
>  	return drm_debug_syslog_enabled(category);
>  }
> 
> +/**
> + * drm_debug_category_printer - construct a &drm_printer that outputs 
> to
> + * pr_debug() if enabled for the given category.
> + * @category: the DRM_UT_* message category this message belongs to
> + * @prefix: trace output prefix
> + *
> + * RETURNS:
> + * The &drm_printer object
> + */
> +static inline struct drm_printer
> +drm_debug_category_printer(enum drm_debug_category category,
> +			   const char *prefix)
> +{
> +	struct drm_printer p = {
> +		.prefix = prefix
> +	};
> +
> +	if (drm_debug_syslog_enabled(category)) {
> +		p.printfn = __drm_printfn_debug_syslog;
> +	} else {
> +		WARN(1, "Debug category %d is inactive.", category);
> +		p.printfn = __drm_printfn_noop;
> +	}
> +
> +	return p;
> +}
> +
>  /*
>   * struct device based logging
>   *