On Wed, 17 Apr 2019 11:30:10 +0200, Timo Wischer wrote: > > On 4/17/19 11:21, Takashi Iwai wrote: > > On Wed, 17 Apr 2019 10:46:11 +0200, > > <twischer@xxxxxxxxxxxxxx> wrote: > >> From: Timo Wischer <twischer@xxxxxxxxxxxxxx> > >> > >> 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? Well, maybe we need to ping ARM people if no one on the lists you Cc'ed give comments. Let's see. Takashi > > > > > > > thanks, > > > > Takashi > > > >> Signed-off-by: Timo Wischer <twischer@xxxxxxxxxxxxxx> > >> --- > >> 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@xxxxxxxxxxxxxxxx > >> https://mailman.alsa-project.org/mailman/listinfo/patch > >> > _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
