On Mon, 07 Dec 2015 08:59:13 +0100,
han.lu@xxxxxxxxx wrote:
>
> From: "Lu, Han" <han.lu@xxxxxxxxx>
>
> In BXT-P A0, HD-Audio DMA requests is later than expected,
> and makes an audio stream sensitive to system latencies when
> 24/32 bits are playing.
> Adjusting threshold of DMA fifo to force the DMA request
> sooner to improve latency tolerance at the expense of power.
>
> v2: move Intel specific code to hda_intel.c
>
> Signed-off-by: Lu, Han <han.lu@xxxxxxxxx>
Applied, thanks.
Takashi
>
> diff --git a/include/sound/hda_register.h b/include/sound/hda_register.h
> index 2ae8812..94dc6a9 100644
> --- a/include/sound/hda_register.h
> +++ b/include/sound/hda_register.h
> @@ -93,6 +93,9 @@ enum { SDI0, SDI1, SDI2, SDI3, SDO0, SDO1, SDO2, SDO3 };
> #define AZX_REG_HSW_EM4 0x100c
> #define AZX_REG_HSW_EM5 0x1010
>
> +/* Skylake/Broxton display HD-A controller Extended Mode registers */
> +#define AZX_REG_SKL_EM4L 0x1040
> +
> /* PCI space */
> #define AZX_PCIREG_TCSEL 0x44
>
> diff --git a/sound/pci/hda/hda_intel.c b/sound/pci/hda/hda_intel.c
> index 963f824..bff5c8b 100644
> --- a/sound/pci/hda/hda_intel.c
> +++ b/sound/pci/hda/hda_intel.c
> @@ -355,6 +355,8 @@ enum {
> ((pci)->device == 0x0d0c) || \
> ((pci)->device == 0x160c))
>
> +#define IS_BROXTON(pci) ((pci)->device == 0x5a98)
> +
> static char *driver_short_names[] = {
> [AZX_DRIVER_ICH] = "HDA Intel",
> [AZX_DRIVER_PCH] = "HDA Intel PCH",
> @@ -506,15 +508,36 @@ static void azx_init_pci(struct azx *chip)
> }
> }
>
> +/*
> + * In BXT-P A0, HD-Audio DMA requests is later than expected,
> + * and makes an audio stream sensitive to system latencies when
> + * 24/32 bits are playing.
> + * Adjusting threshold of DMA fifo to force the DMA request
> + * sooner to improve latency tolerance at the expense of power.
> + */
> +static void bxt_reduce_dma_latency(struct azx *chip)
> +{
> + u32 val;
> +
> + val = azx_readl(chip, SKL_EM4L);
> + val &= (0x3 << 20);
> + azx_writel(chip, SKL_EM4L, val);
> +}
> +
> static void hda_intel_init_chip(struct azx *chip, bool full_reset)
> {
> struct hdac_bus *bus = azx_bus(chip);
> + struct pci_dev *pci = chip->pci;
>
> if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
> snd_hdac_set_codec_wakeup(bus, true);
> azx_init_chip(chip, full_reset);
> if (chip->driver_caps & AZX_DCAPS_I915_POWERWELL)
> snd_hdac_set_codec_wakeup(bus, false);
> +
> + /* reduce dma latency to avoid noise */
> + if (IS_BROXTON(pci))
> + bxt_reduce_dma_latency(chip);
> }
>
> /* calculate runtime delay from LPIB */
> --
> 2.5.0
>
_______________________________________________
Alsa-devel mailing list
Alsa-devel@xxxxxxxxxxxxxxxx
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
