Messages in this thread | | | Subject | Re: [ALSA patch] [PATCH] ALSA: pcm: Enable MMAP status and control for ARMv7 and ARMv8 | From | Timo Wischer <> | Date | Wed, 17 Apr 2019 11:30:10 +0200 |
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On 4/17/19 11:21, Takashi Iwai wrote: > On Wed, 17 Apr 2019 10:46:11 +0200, > <twischer@de.adit-jv.com> wrote: >> From: Timo Wischer <twischer@de.adit-jv.com> >> >> Since ARMv7 hardware cache coherence is supported. >> "The SCU maintains coherency between the individual data caches in the >> Cortex-A5 MPCore processor using a variation of the MOESI protocol" [1]. >> >> Therefore this patch enables the MMAP access to the status and control >> structures. This avoids HWSYYNC ioctl calls and therefore lowers the CPU >> usage. >> >> [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0434c/ >> BABJECBF.html > Interesting... I thought it would never work properly on ARM. > If it really works like that, I'd happily apply the change. > But I'd like to hear a confirmation from ARM people before merging > such an intensive change.
Hi Takashi,
do I need to send this patch to any other mailing list or do you think some corresponding guy is already on the lists I have used?
> > > thanks, > > Takashi > >> Signed-off-by: Timo Wischer <twischer@de.adit-jv.com> >> --- >> sound/core/pcm_native.c | 3 ++- >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c >> index 1d84529..b8019ef 100644 >> --- a/sound/core/pcm_native.c >> +++ b/sound/core/pcm_native.c >> @@ -3225,7 +3225,8 @@ static __poll_t snd_pcm_poll(struct file *file, poll_table *wait) >> * Only on coherent architectures, we can mmap the status and the control records >> * for effcient data transfer. On others, we have to use HWSYNC ioctl... >> */ >> -#if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_ALPHA) >> +#if defined(CONFIG_X86) || defined(CONFIG_PPC) || defined(CONFIG_ALPHA) || \ >> + (defined(CONFIG_ARM) && defined(CONFIG_CPU_V7)) || defined(CONFIG_ARM64) >> /* >> * mmap status record >> */ >> -- >> 2.7.4 >> >> _______________________________________________ >> Patch mailing list >> Patch@alsa-project.org >> https://mailman.alsa-project.org/mailman/listinfo/patch >>
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