81be109349
ALSA PCM core has an optimized way to communicate with user-space for its control and status data via mmap on the supported architectures like x86. Depending on the situation, however, we'd rather want to enforce user-space notifying the applptr or hwptr change explicitly via ioctl. For example, the upcoming non-contig and non-coherent buffer handling would need an explicit sync, and this needs to catch the applptr and hwptr changes. Also, ASoC SOF driver will have the SPIB support that has the similar requirement for the explicit control of the applptr and hwptr. This patch adds the new PCM hardware info flag, SNDRV_PCM_INFO_EXPLICIT_SYNC. When this flag is set, PCM core disables both the control and the status mmap, which enforces user-space to update via SYNC_PTR ioctl. In that way, drivers can catch the applptr and hwptr update and apply the sync operation if needed. Link: https://lore.kernel.org/r/20210812113818.6479-1-tiwai@suse.de Link: https://lore.kernel.org/r/20210610205326.1176400-1-pierre-louis.bossart@linux.intel.com Link: https://lore.kernel.org/r/20210813082142.5375-1-tiwai@suse.de Signed-off-by: Takashi Iwai <tiwai@suse.de> |
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| asm-generic | ||
| drm | ||
| linux | ||
| misc | ||
| mtd | ||
| rdma | ||
| scsi | ||
| sound | ||
| video | ||
| xen | ||
| Kbuild | ||