> -----Original Message----- > From: Takashi Iwai [mailto:tiwai@xxxxxxx] > Sent: Monday, December 7, 2015 2:57 PM > To: Lu, Han > Cc: libin.yang@xxxxxxxxxxxxxxx; mengdong.lin@xxxxxxxxxxxxxxx; > han.lu@xxxxxxxxxxxxxxx; alsa-devel@xxxxxxxxxxxxxxxx > Subject: Re: [PATCH 1/1] audio: Fix playback noise with 24/32 bit sample size > on BXT > > On Mon, 07 Dec 2015 03:51:49 +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. > > > > Signed-off-by: Lu, Han <han.lu@xxxxxxxxx> > > It's a wrong place to patch. hda_controller.c is for generic HD-audio. The > Intel-specific code should go into hda_intel.c. > Sorry. I submitted patch V2, please review, Thanks. BR, Han > > 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_controller.c > > b/sound/pci/hda/hda_controller.c index 22dbfa5..6c2aa4c 100644 > > --- a/sound/pci/hda/hda_controller.c > > +++ b/sound/pci/hda/hda_controller.c > > @@ -27,6 +27,7 @@ > > #include <linux/module.h> > > #include <linux/pm_runtime.h> > > #include <linux/slab.h> > > +#include <linux/pci.h> > > #include <sound/core.h> > > #include <sound/initval.h> > > #include "hda_controller.h" > > @@ -34,6 +35,8 @@ > > #define CREATE_TRACE_POINTS > > #include "hda_controller_trace.h" > > > > +#define is_broxton(pci) ((pci)->device == 0x5a98) > > + > > /* DSP lock helpers */ > > #define dsp_lock(dev) snd_hdac_dsp_lock(azx_stream(dev)) > > #define dsp_unlock(dev) > snd_hdac_dsp_unlock(azx_stream(dev)) > > @@ -880,14 +883,35 @@ > > EXPORT_SYMBOL_GPL(snd_hda_codec_load_dsp_cleanup); > > #endif /* CONFIG_SND_HDA_DSP_LOADER */ > > > > /* > > + * 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); > > +} > > + > > +/* > > * reset and start the controller registers > > */ > > void azx_init_chip(struct azx *chip, bool full_reset) { > > + struct pci_dev *pci = chip->pci; > > + > > if (snd_hdac_bus_init_chip(azx_bus(chip), full_reset)) { > > /* correct RINTCNT for CXT */ > > if (chip->driver_caps & AZX_DCAPS_CTX_WORKAROUND) > > azx_writew(chip, RINTCNT, 0xc0); > > + /* reduce dma latency to avoid noise */ > > + if (is_broxton(pci)) > > + bxt_reduce_dma_latency(chip); > > } > > } > > EXPORT_SYMBOL_GPL(azx_init_chip); > > -- > > 2.5.0 > > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
