[alsa-devel] [PATCH 2/2 v2] ALSA: hda - set intel audio clock to a proper value

[Takashi Iwai]

On Thu, 06 Apr 2017 13:18:21 +0200,
libin.yang at intel.com wrote:
> 
> From: Libin Yang <libin.yang at intel.com>
> 
> On some Intel platforms, the audio clock may not be set correctly
> with initial setting. This will cause the audio playback/capture
> rates wrong.
> 
> This patch checks the audio clock setting and will set it to a
> proper value if it is set incorrectly.
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=188411
> 
> Signed-off-by: Libin Yang <libin.yang at intel.com>

Applied, thanks.


Takashi

> ---
>  sound/pci/hda/hda_intel.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 95 insertions(+)
> 
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index c8256a8..7b85132 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -539,6 +539,98 @@ static void bxt_reduce_dma_latency(struct azx *chip)
>  	azx_writel(chip, SKL_EM4L, val);
>  }
>  
> +/*
> + * ML_LCAP bits:
> + *  bit 0: 6 MHz Supported
> + *  bit 1: 12 MHz Supported
> + *  bit 2: 24 MHz Supported
> + *  bit 3: 48 MHz Supported
> + *  bit 4: 96 MHz Supported
> + *  bit 5: 192 MHz Supported
> + */
> +static int intel_get_lctl_scf(struct azx *chip)
> +{
> +	struct hdac_bus *bus = azx_bus(chip);
> +	static int preferred_bits[] = { 2, 3, 1, 4, 5 };
> +	u32 val, t;
> +	int i;
> +
> +	val = readl(bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCAP);
> +
> +	for (i = 0; i < ARRAY_SIZE(preferred_bits); i++) {
> +		t = preferred_bits[i];
> +		if (val & (1 << t))
> +			return t;
> +	}
> +
> +	dev_warn(chip->card->dev, "set audio clock frequency to 6MHz");
> +	return 0;
> +}
> +
> +static int intel_ml_lctl_set_power(struct azx *chip, int state)
> +{
> +	struct hdac_bus *bus = azx_bus(chip);
> +	u32 val;
> +	int timeout;
> +
> +	/*
> +	 * the codecs are sharing the first link setting by default
> +	 * If other links are enabled for stream, they need similar fix
> +	 */
> +	val = readl(bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCTL);
> +	val &= ~AZX_MLCTL_SPA;
> +	val |= state << AZX_MLCTL_SPA_SHIFT;
> +	writel(val, bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCTL);
> +	/* wait for CPA */
> +	timeout = 50;
> +	while (timeout) {
> +		if (((readl(bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCTL)) &
> +		    AZX_MLCTL_CPA) == (state << AZX_MLCTL_CPA_SHIFT))
> +			return 0;
> +		timeout--;
> +		udelay(10);
> +	}
> +
> +	return -1;
> +}
> +
> +static void intel_init_lctl(struct azx *chip)
> +{
> +	struct hdac_bus *bus = azx_bus(chip);
> +	u32 val;
> +	int ret;
> +
> +	/* 0. check lctl register value is correct or not */
> +	val = readl(bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCTL);
> +	/* if SCF is already set, let's use it */
> +	if ((val & ML_LCTL_SCF_MASK) != 0)
> +		return;
> +
> +	/*
> +	 * Before operating on SPA, CPA must match SPA.
> +	 * Any deviation may result in undefined behavior.
> +	 */
> +	if (((val & AZX_MLCTL_SPA) >> AZX_MLCTL_SPA_SHIFT) !=
> +		((val & AZX_MLCTL_CPA) >> AZX_MLCTL_CPA_SHIFT))
> +		return;
> +
> +	/* 1. turn link down: set SPA to 0 and wait CPA to 0 */
> +	ret = intel_ml_lctl_set_power(chip, 0);
> +	udelay(100);
> +	if (ret)
> +		goto set_spa;
> +
> +	/* 2. update SCF to select a properly audio clock*/
> +	val &= ~ML_LCTL_SCF_MASK;
> +	val |= intel_get_lctl_scf(chip);
> +	writel(val, bus->mlcap + AZX_ML_BASE + AZX_REG_ML_LCTL);
> +
> +set_spa:
> +	/* 4. turn link up: set SPA to 1 and wait CPA to 1 */
> +	intel_ml_lctl_set_power(chip, 1);
> +	udelay(100);
> +}
> +
>  static void hda_intel_init_chip(struct azx *chip, bool full_reset)
>  {
>  	struct hdac_bus *bus = azx_bus(chip);
> @@ -564,6 +656,9 @@ static void hda_intel_init_chip(struct azx *chip, bool full_reset)
>  	/* reduce dma latency to avoid noise */
>  	if (IS_BXT(pci))
>  		bxt_reduce_dma_latency(chip);
> +
> +	if (bus->mlcap != NULL)
> +		intel_init_lctl(chip);
>  }
>  
>  /* calculate runtime delay from LPIB */
> -- 
> 2.7.4
>