[Intel-gfx] [PATCH] drm/i915/dp: refactor aux_ch_name()

[Andrzej Hajda]

On 22.09.2023 12:56, Jani Nikula wrote:
> Convert aux_ch_name() to a helper that prints a string to a caller
> provided buffer, and use it to get more consistent aux channel
> debugs. Now that all users of aux_ch_name() are in intel_dp_aux.c, we
> can make it static too.
> 
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
> ---
>   drivers/gpu/drm/i915/display/intel_display.h |  2 -
>   drivers/gpu/drm/i915/display/intel_dp_aux.c  | 41 ++++++++++++--------
>   2 files changed, 25 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.h b/drivers/gpu/drm/i915/display/intel_display.h
> index 49ac8473b988..9f252d1f03a7 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.h
> +++ b/drivers/gpu/drm/i915/display/intel_display.h
> @@ -190,8 +190,6 @@ enum aux_ch {
>   	AUX_CH_E_XELPD,
>   };
>   
> -#define aux_ch_name(a) ((a) + 'A')
> -
>   enum phy {
>   	PHY_NONE = -1,
>   
> diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> index b90cad7f567b..4431b6290c4c 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c
> @@ -14,6 +14,21 @@
>   #include "intel_pps.h"
>   #include "intel_tc.h"
>   
> +#define AUX_CH_NAME_BUFSIZE	6
> +
> +static const char *aux_ch_name(struct drm_i915_private *i915,
> +			       char *buf, int size, enum aux_ch aux_ch)
> +{
> +	if (DISPLAY_VER(i915) >= 13 && aux_ch >= AUX_CH_D_XELPD)
> +		snprintf(buf, size, "%c", 'A' + aux_ch - AUX_CH_D_XELPD + AUX_CH_D);
> +	else if (DISPLAY_VER(i915) >= 12 && aux_ch >= AUX_CH_USBC1)
> +		snprintf(buf, size, "USBC%c", '1' + aux_ch - AUX_CH_USBC1);
> +	else
> +		snprintf(buf, size, "%c", 'A' + aux_ch);
> +
> +	return buf;
> +}
> +
>   u32 intel_dp_aux_pack(const u8 *src, int src_bytes)
>   {
>   	int i;
> @@ -728,6 +743,7 @@ void intel_dp_aux_init(struct intel_dp *intel_dp)
>   	struct intel_digital_port *dig_port = dp_to_dig_port(intel_dp);
>   	struct intel_encoder *encoder = &dig_port->base;
>   	enum aux_ch aux_ch = dig_port->aux_ch;
> +	char buf[AUX_CH_NAME_BUFSIZE];
>   
>   	if (DISPLAY_VER(dev_priv) >= 14) {
>   		intel_dp->aux_ch_ctl_reg = xelpdp_aux_ctl_reg;
> @@ -764,18 +780,9 @@ void intel_dp_aux_init(struct intel_dp *intel_dp)
>   	drm_dp_aux_init(&intel_dp->aux);
>   
>   	/* Failure to allocate our preferred name is not critical */
> -	if (DISPLAY_VER(dev_priv) >= 13 && aux_ch >= AUX_CH_D_XELPD)
> -		intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX %c/%s",
> -					       aux_ch_name(aux_ch - AUX_CH_D_XELPD + AUX_CH_D),
> -					       encoder->base.name);
> -	else if (DISPLAY_VER(dev_priv) >= 12 && aux_ch >= AUX_CH_USBC1)
> -		intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX USBC%c/%s",
> -					       aux_ch - AUX_CH_USBC1 + '1',
> -					       encoder->base.name);
> -	else
> -		intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX %c/%s",
> -					       aux_ch_name(aux_ch),
> -					       encoder->base.name);
> +	intel_dp->aux.name = kasprintf(GFP_KERNEL, "AUX %s/%s",
> +				       aux_ch_name(dev_priv, buf, sizeof(buf), aux_ch),
> +				       encoder->base.name);

With define like:

#define aux_ch_name_smart(dev_priv, aux_ch) aux_ch_name(dev_priv, 
(char[AUX_CH_NAME_BUFSIZE]){}, AUX_CH_NAME_BUFSIZE, aux_ch)

you could get rid of local variable buf, and two extra arguments in 
call. The price is gcc macro magic and maybe less visible life-time 
constraints, no strong suggestion :)

Reviewed-by: Andrzej Hajda <andrzej.hajda at intel.com>

Regards
Andrzej


>   
>   	intel_dp->aux.transfer = intel_dp_aux_transfer;
>   	cpu_latency_qos_add_request(&intel_dp->pm_qos, PM_QOS_DEFAULT_VALUE);
> @@ -819,6 +826,7 @@ enum aux_ch intel_dp_aux_ch(struct intel_encoder *encoder)
>   	struct intel_encoder *other;
>   	const char *source;
>   	enum aux_ch aux_ch;
> +	char buf[AUX_CH_NAME_BUFSIZE];
>   
>   	aux_ch = intel_bios_dp_aux_ch(encoder->devdata);
>   	source = "VBT";
> @@ -836,16 +844,17 @@ enum aux_ch intel_dp_aux_ch(struct intel_encoder *encoder)
>   	other = get_encoder_by_aux_ch(encoder, aux_ch);
>   	if (other) {
>   		drm_dbg_kms(&i915->drm,
> -			    "[ENCODER:%d:%s] AUX CH %c already claimed by [ENCODER:%d:%s]\n",
> -			    encoder->base.base.id, encoder->base.name, aux_ch_name(aux_ch),
> +			    "[ENCODER:%d:%s] AUX CH %s already claimed by [ENCODER:%d:%s]\n",
> +			    encoder->base.base.id, encoder->base.name,
> +			    aux_ch_name(i915, buf, sizeof(buf), aux_ch),
>   			    other->base.base.id, other->base.name);
>   		return AUX_CH_NONE;
>   	}
>   
>   	drm_dbg_kms(&i915->drm,
> -		    "[ENCODER:%d:%s] Using AUX CH %c (%s)\n",
> +		    "[ENCODER:%d:%s] Using AUX CH %s (%s)\n",
>   		    encoder->base.base.id, encoder->base.name,
> -		    aux_ch_name(aux_ch), source);
> +		    aux_ch_name(i915, buf, sizeof(buf), aux_ch), source);
>   
>   	return aux_ch;
>   }