4f550df58f
Modules: VIA82xx driver The change only affects the via823x kind of chips. Here the via8233_pcm_pointer_hw() function (named snd_via8233_pcm_pointer() before) needed to loop until a non zero position is red from the chip. Measurements have shown that more than 200 loops are typically needed on an Athlon64. As io-reads cost many cycles, those loops sum up huge. via8233_pcm_pointer_hw() runs either in interrupt or with interrupts disabled. So it introduces significant interrupt latency. The patch introduces a calculated position value hwptr_done, that is updated by the interrupt routine when a period is completed. It is only used, if the 823x chip returns a zero position, which can't be interpreted reliably. Further optimisation is applied on the 8233 chip's interrupt routine: Only the SGD_SHADOW is read, as it contains all infos needed. We ommit ~5 more register reads that way. Signed-off-by: Karsten Wiese <annabellesgarden@yahoo.de> Signed-off-by: Takashi Iwai <tiwai@suse.de> |
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| .. | ||
| arm | ||
| core | ||
| drivers | ||
| i2c | ||
| isa | ||
| mips | ||
| oss | ||
| parisc | ||
| pci | ||
| pcmcia | ||
| ppc | ||
| sparc | ||
| synth | ||
| usb | ||
| Kconfig | ||
| last.c | ||
| Makefile | ||
| sound_core.c | ||
| sound_firmware.c | ||