[alsa-devel] [PATCH 3/3] ALSA: hda - restore BCLK M/N value as per CDCLK for HSW/BDW display HDA controller

[Takashi Iwai]

At Wed,  2 Jul 2014 22:44:07 +0800,
mengdong.lin at intel.com wrote:
> 
> From: Mengdong Lin <mengdong.lin at intel.com>
> 
> For HSW/BDW display HD-A controller, this patch restores BCLK by setting the
> M/N values as per the core display clock (CDCLK) queried from i915 display
> driver.
> 
> And the audio driver will also restore BCLK in azx_first_init() since the
> display driver can turn off the shared power in boot phase if only eDP is
> connected and M/N values will be lost and must be reprogrammed.
> 
> Signed-off-by: Mengdong Lin <mengdong.lin at intel.com>
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 25753db..c7dfd1d 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -299,10 +299,6 @@ static char *driver_short_names[] = {
>  
>  struct hda_intel {
>  	struct azx chip;
> -
> -	/* HSW/BDW display HDA controller to restore BCLK from CDCLK */
> -	unsigned int bclk_m;
> -	unsigned int bclk_n;
>  };
>  
>  
> @@ -598,20 +594,41 @@ static int param_set_xint(const char *val, const struct kernel_param *kp)
>  #define azx_del_card_list(chip) /* NOP */
>  #endif /* CONFIG_PM */
>  
> -static void haswell_save_bclk(struct azx *chip)
> -{
> -	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
> -
> -	hda->bclk_m = azx_readw(chip, EM4);
> -	hda->bclk_n = azx_readw(chip, EM5);
> -}
>  
>  static void haswell_restore_bclk(struct azx *chip)
>  {
> -	struct hda_intel *hda = container_of(chip, struct hda_intel, chip);
> +	int cdclk_freq;
> +	unsigned int bclk_m, bclk_n;
> +
> +	cdclk_freq = hda_get_display_clk();
> +	switch (cdclk_freq) {
> +	case 337500:
> +		bclk_m = 16;
> +		bclk_n = 225;
> +		break;
> +
> +	case 450000: /* default CDCLK 450MHz */
> +		bclk_m = 4;
> +		bclk_n = 75;
> +		break;
> +
> +	case 540000:
> +		bclk_m = 4;
> +		bclk_n = 90;
> +		break;
> +
> +	case 675000:
> +		bclk_m = 8;
> +		bclk_n = 225;
> +		break;
>  
> -	azx_writew(chip, EM4, hda->bclk_m);
> -	azx_writew(chip, EM5, hda->bclk_n);
> +	default:
> +		bclk_m = 4;
> +		bclk_n = 75;

You can put "default:" around "case 45000:", and move the comment
about default CDCLK there.

> +	}
> +
> +	azx_writew(chip, EM4, bclk_m);
> +	azx_writew(chip, EM5, bclk_n);
>  }

IMO, the whole function can be moved to hda_i915.c and provided as a
function such as hda_set_display_clk().  Then you can drop
hda_get_display_clk() but call get_cdclk() internally.

Also, all these patches may have Cc to stable, right?


thanks,

Takashi