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ALSA: hda: add member to store ratio for stripe control

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Stripe control programming is governed by following formula, which is
referenced from the HD Audio specification(Revision 1.0a).
  { ((num_channels * bits_per_sample) / number of SDOs) >= 8 }

Currently above is implemented in snd_hdac_get_stream_stripe_ctl().
This patch introduces a structure member to store the default factor
of '8'. If any HW wants to use a different value, this member can be
easily updated.

Signed-off-by: Sameer Pujar <spujar@nvidia.com>
Link: https://lore.kernel.org/r/1588580176-2801-3-git-send-email-spujar@nvidia.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Sameer Pujar 2020-05-04 13:46:15 +05:30 committed by Takashi Iwai
parent bb9b02a458
commit 67ae482a59
3 changed files with 16 additions and 1 deletions
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3
include/sound/hdaudio.h
View File

@ -364,6 +364,9 @@ struct hdac_bus {
/* link management */
struct list_head hlink_list;
bool cmd_dma_state;
/* factor used to derive STRIPE control value */
unsigned int sdo_limit;
};
int snd_hdac_bus_init(struct hdac_bus *bus, struct device *dev,

12
sound/hda/hdac_controller.c
View File

@ -527,6 +527,18 @@ bool snd_hdac_bus_init_chip(struct hdac_bus *bus, bool full_reset)
}
bus->chip_init = true;
/*
* Default value of '8' is as per the HD audio specification (Rev 1.0a).
* Following relation is used to derive STRIPE control value.
* For sample rate <= 48K:
* { ((num_channels * bits_per_sample) / number of SDOs) >= 8 }
* For sample rate > 48K:
* { ((num_channels * bits_per_sample * rate/48000) /
* number of SDOs) >= 8 }
*/
bus->sdo_limit = 8;
return true;
}
EXPORT_SYMBOL_GPL(snd_hdac_bus_init_chip);

2
sound/hda/hdac_stream.c
View File

@ -38,7 +38,7 @@ int snd_hdac_get_stream_stripe_ctl(struct hdac_bus *bus,
else
value = (channels * bits_per_sample) / sdo_line;
if (value >= 8)
if (value >= bus->sdo_limit)
break;
}