CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE=y
CONFIG_ARCH_DISCARD_MEMBLOCK=y
CONFIG_ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE=y
CONFIG_ARCH_HAS_RESET_CONTROLLER=y
# CONFIG_ARCH_HAS_SG_CHAIN is not set
CONFIG_ARCH_HAVE_CUSTOM_GPIO_H=y
CONFIG_ARCH_HIBERNATION_POSSIBLE=y
CONFIG_ARCH_MIGHT_HAVE_PC_PARPORT=y
CONFIG_ARCH_MIGHT_HAVE_PC_SERIO=y
CONFIG_ARCH_REQUIRE_GPIOLIB=y
CONFIG_ARCH_SUSPEND_POSSIBLE=y
CONFIG_ARCH_WANT_IPC_PARSE_VERSION=y
CONFIG_AT803X_PHY=y
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
CONFIG_CEVT_R4K=y
CONFIG_CLKDEV_LOOKUP=y
CONFIG_CLKEVT_RT3352=y
CONFIG_CLKSRC_MMIO=y
CONFIG_CLKSRC_OF=y
CONFIG_CLONE_BACKWARDS=y
CONFIG_CMDLINE="rootfstype=squashfs,jffs2"
CONFIG_CMDLINE_BOOL=y
# CONFIG_CMDLINE_OVERRIDE is not set
CONFIG_CPU_GENERIC_DUMP_TLB=y
CONFIG_CPU_HAS_PREFETCH=y
CONFIG_CPU_HAS_SYNC=y
CONFIG_CPU_LITTLE_ENDIAN=y
CONFIG_CPU_MIPS32=y
# CONFIG_CPU_MIPS32_R1 is not set
CONFIG_CPU_MIPS32_R2=y
CONFIG_CPU_MIPSR2=y
CONFIG_CPU_NEEDS_NO_SMARTMIPS_OR_MICROMIPS=y
CONFIG_CPU_R4K_CACHE_TLB=y
CONFIG_CPU_R4K_FPU=y
CONFIG_CPU_SUPPORTS_32BIT_KERNEL=y
CONFIG_CPU_SUPPORTS_HIGHMEM=y
CONFIG_CPU_SUPPORTS_MSA=y
CONFIG_CSRC_R4K=y
CONFIG_DEBUG_PINCTRL=y
CONFIG_DMA_NONCOHERENT=y
# CONFIG_DTB_MT7620A_EVAL is not set
CONFIG_DTB_RT_NONE=y
CONFIG_DTC=y
CONFIG_EARLY_PRINTK=y
CONFIG_GENERIC_ATOMIC64=y
CONFIG_GENERIC_CLOCKEVENTS=y
CONFIG_GENERIC_CLOCKEVENTS_BUILD=y
CONFIG_GENERIC_CMOS_UPDATE=y
CONFIG_GENERIC_IO=y
CONFIG_GENERIC_IRQ_SHOW=y
CONFIG_GENERIC_PCI_IOMAP=y
CONFIG_GENERIC_PHY=y
CONFIG_GENERIC_SMP_IDLE_THREAD=y
CONFIG_GPIOLIB=y
CONFIG_GPIO_DEVRES=y
CONFIG_GPIO_MT7621=y
# CONFIG_GPIO_RALINK is not set
CONFIG_GPIO_SYSFS=y
CONFIG_HARDWARE_WATCHPOINTS=y
CONFIG_HAS_DMA=y
CONFIG_HAS_IOMEM=y
CONFIG_HAS_IOPORT_MAP=y
# CONFIG_HAVE_64BIT_ALIGNED_ACCESS is not set
CONFIG_HAVE_ARCH_JUMP_LABEL=y
CONFIG_HAVE_ARCH_KGDB=y
CONFIG_HAVE_ARCH_SECCOMP_FILTER=y
CONFIG_HAVE_ARCH_TRACEHOOK=y
# CONFIG_HAVE_BOOTMEM_INFO_NODE is not set
CONFIG_HAVE_BPF_JIT=y
CONFIG_HAVE_CC_STACKPROTECTOR=y
CONFIG_HAVE_CLK=y
CONFIG_HAVE_CONTEXT_TRACKING=y
CONFIG_HAVE_C_RECORDMCOUNT=y
CONFIG_HAVE_DEBUG_KMEMLEAK=y
CONFIG_HAVE_DEBUG_STACKOVERFLOW=y
CONFIG_HAVE_DMA_API_DEBUG=y
CONFIG_HAVE_DMA_ATTRS=y
CONFIG_HAVE_DMA_CONTIGUOUS=y
CONFIG_HAVE_DYNAMIC_FTRACE=y
CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y
CONFIG_HAVE_FUNCTION_TRACER=y
CONFIG_HAVE_GENERIC_DMA_COHERENT=y
CONFIG_HAVE_IDE=y
CONFIG_HAVE_KVM=y
CONFIG_HAVE_MACH_CLKDEV=y
CONFIG_HAVE_MEMBLOCK=y
CONFIG_HAVE_MEMBLOCK_NODE_MAP=y
CONFIG_HAVE_MOD_ARCH_SPECIFIC=y
CONFIG_HAVE_NET_DSA=y
CONFIG_HAVE_OPROFILE=y
CONFIG_HAVE_PERF_EVENTS=y
CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
CONFIG_HW_HAS_PCI=y
CONFIG_HZ_PERIODIC=y
CONFIG_ICPLUS_PHY=y
CONFIG_IMAGE_CMDLINE_HACK=y
CONFIG_INITRAMFS_SOURCE=""
CONFIG_IRQCHIP=y
CONFIG_IRQ_CPU=y
CONFIG_IRQ_DOMAIN=y
CONFIG_IRQ_FORCED_THREADING=y
CONFIG_IRQ_INTC=y
CONFIG_IRQ_WORK=y
CONFIG_LIBFDT=y
CONFIG_MDIO_BOARDINFO=y
CONFIG_MIPS=y
# CONFIG_MIPS_HUGE_TLB_SUPPORT is not set
CONFIG_MIPS_L1_CACHE_SHIFT=5
# CONFIG_MIPS_MACHINE is not set
CONFIG_MODULES_USE_ELF_REL=y
CONFIG_MT7621_WDT=y
# CONFIG_MTD_CFI_INTELEXT is not set
CONFIG_MTD_CMDLINE_PARTS=y
CONFIG_MTD_M25P80=y
CONFIG_MTD_NAND_MT7620=y
CONFIG_MTD_PHYSMAP=y
CONFIG_MTD_SPI_NOR=y
CONFIG_MTD_SPLIT_FIRMWARE=y
CONFIG_MTD_SPLIT_UIMAGE_FW=y
CONFIG_NEED_DMA_MAP_STATE=y
CONFIG_NEED_PER_CPU_KM=y
CONFIG_NET_RALINK=y
CONFIG_NET_RALINK_ESW_RT3052=y
# CONFIG_NET_RALINK_MT7620 is not set
CONFIG_NET_RALINK_RT305X=y
CONFIG_NO_GENERIC_PCI_IOPORT_MAP=y
# CONFIG_NO_IOPORT_MAP is not set
CONFIG_OF=y
CONFIG_OF_ADDRESS=y
CONFIG_OF_ADDRESS_PCI=y
CONFIG_OF_EARLY_FLATTREE=y
CONFIG_OF_FLATTREE=y
CONFIG_OF_GPIO=y
CONFIG_OF_IRQ=y
CONFIG_OF_MDIO=y
CONFIG_OF_MTD=y
CONFIG_OF_NET=y
CONFIG_OF_PCI=y
CONFIG_OF_PCI_IRQ=y
CONFIG_PAGEFLAGS_EXTENDED=y
CONFIG_PCI=y
CONFIG_PCI_DOMAINS=y
CONFIG_PERF_USE_VMALLOC=y
CONFIG_PHYLIB=y
CONFIG_PHY_RALINK_USB=y
CONFIG_PINCTRL=y
CONFIG_PINCTRL_RT2880=y
# CONFIG_PINCTRL_SINGLE is not set
# CONFIG_PREEMPT_RCU is not set
CONFIG_RALINK=y
CONFIG_RALINK_USBPHY=y
# CONFIG_RALINK_WDT is not set
# CONFIG_RCU_STALL_COMMON is not set
CONFIG_RESET_CONTROLLER=y
# CONFIG_SCSI_DMA is not set
CONFIG_SERIAL_8250_NR_UARTS=4
CONFIG_SERIAL_8250_RT288X=y
CONFIG_SERIAL_OF_PLATFORM=y
# CONFIG_SLAB is not set
CONFIG_SLUB=y
CONFIG_SOC_MT7620=y
# CONFIG_SOC_MT7621 is not set
# CONFIG_SOC_RT288X is not set
# CONFIG_SOC_RT305X is not set
# CONFIG_SOC_RT3883 is not set
CONFIG_SPI=y
CONFIG_SPI_MASTER=y
CONFIG_SPI_MT7621=y
# CONFIG_SPI_RT2880 is not set
CONFIG_SWCONFIG=y
CONFIG_SYS_HAS_CPU_MIPS32_R1=y
CONFIG_SYS_HAS_CPU_MIPS32_R2=y
CONFIG_SYS_HAS_EARLY_PRINTK=y
CONFIG_SYS_SUPPORTS_32BIT_KERNEL=y
CONFIG_SYS_SUPPORTS_ARBIT_HZ=y
CONFIG_SYS_SUPPORTS_LITTLE_ENDIAN=y
CONFIG_SYS_SUPPORTS_MIPS16=y
CONFIG_TICK_CPU_ACCOUNTING=y
CONFIG_USB_PHY=y
CONFIG_USB_SUPPORT=y
CONFIG_USE_OF=y
CONFIG_WATCHDOG_CORE=y
CONFIG_ZONE_DMA_FLAG=0
d='n2' href='#n2'>2
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From 84ad00eb76af34f8a6c6941dc6da80a3f735b207 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Wed, 13 Jan 2016 19:44:47 +0100
Subject: [PATCH 410/454] bcm2835: interpolate audio delay
It appears the GPU only sends us a message all 10ms to update
the playback progress. Other than this, the playback position
(what SNDRV_PCM_IOCTL_DELAY will return) is not updated at all.
Userspace will see jitter up to 10ms in the audio position.
Make this a bit nicer for userspace by interpolating the
position using the CPU clock.
I'm not sure if setting snd_pcm_runtime.delay is the right
approach for this. Or if there is maybe an already existing
mechanism for position interpolation in the ALSA core.
I only set SNDRV_PCM_INFO_BATCH because this appears to remove
at least one situation snd_pcm_runtime.delay is used, so I have
to worry less in which place I have to update this field, or
how it interacts with the rest of ALSA.
In the future, it might be nice to use VC_AUDIO_MSG_TYPE_LATENCY.
One problem is that it requires sending a videocore message, and
waiting for a reply, which could make the implementation much
harder due to locking and synchronization requirements.
---
.../vc04_services/bcm2835-audio/bcm2835-pcm.c | 13 +++++++++++--
.../staging/vc04_services/bcm2835-audio/bcm2835.h | 1 +
2 files changed, 12 insertions(+), 2 deletions(-)
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-pcm.c
@@ -22,7 +22,7 @@
/* hardware definition */
static const struct snd_pcm_hardware snd_bcm2835_playback_hw = {
.info = (SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER |
- SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID),
+ SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID | SNDRV_PCM_INFO_BATCH),
.formats = SNDRV_PCM_FMTBIT_U8 | SNDRV_PCM_FMTBIT_S16_LE,
.rates = SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000,
.rate_min = 8000,
@@ -93,6 +93,8 @@ void bcm2835_playback_fifo(struct bcm283
alsa_stream->pos %= alsa_stream->buffer_size;
}
+ alsa_stream->interpolate_start = ktime_get_ns();
+
if (alsa_stream->substream) {
if (new_period)
snd_pcm_period_elapsed(alsa_stream->substream);
@@ -323,6 +325,7 @@ static int snd_bcm2835_pcm_prepare(struc
alsa_stream->buffer_size = snd_pcm_lib_buffer_bytes(substream);
alsa_stream->period_size = snd_pcm_lib_period_bytes(substream);
alsa_stream->pos = 0;
+ alsa_stream->interpolate_start = ktime_get_ns();
audio_debug("buffer_size=%d, period_size=%d pos=%d frame_bits=%d\n",
alsa_stream->buffer_size, alsa_stream->period_size,
@@ -415,13 +418,19 @@ snd_bcm2835_pcm_pointer(struct snd_pcm_s
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct bcm2835_alsa_stream *alsa_stream = runtime->private_data;
-
+ u64 now = ktime_get_ns();
audio_debug("pcm_pointer... (%d) hwptr=%d appl=%d pos=%d\n", 0,
frames_to_bytes(runtime, runtime->status->hw_ptr),
frames_to_bytes(runtime, runtime->control->appl_ptr),
alsa_stream->pos);
+ /* Give userspace better delay reporting by interpolating between GPU
+ * notifications, assuming audio speed is close enough to the clock
+ * used for ktime */
+ if (alsa_stream->interpolate_start && alsa_stream->interpolate_start < now)
+ runtime->delay = -(int)div_u64((now - alsa_stream->interpolate_start) * runtime->rate, 1000000000);
+
return snd_pcm_indirect_playback_pointer(substream,
&alsa_stream->pcm_indirect,
alsa_stream->pos);
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835.h
@@ -137,6 +137,7 @@ struct bcm2835_alsa_stream {
unsigned int pos;
unsigned int buffer_size;
unsigned int period_size;
+ u64 interpolate_start;
atomic_t retrieved;
struct bcm2835_audio_instance *instance;
|