On Sat, Oct 10, 2015 at 01:35:57PM -0700, Nicolin Chen wrote: > On Sat, Oct 10, 2015 at 05:03:07PM -0300, Fabio Estevam wrote: > > On Sat, Oct 10, 2015 at 7:26 AM, Shengjiu Wang > > <shengjiu.wang@xxxxxxxxxxxxx> wrote: > > > > > I think spba clock should be used by the audio IP not DMA, because in same > > > situation the FSL_SSI doesn't need this clock. > > > > According to this commit from FSL BSP, the SSI2 port on MX53 is > > connected to SPBA and needs the SPBA clock: > > > > http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/commit/arch/arm/mach-mx5/clock.c?h=imx_2.6.35_maintain&id=2438f48431b7aff00a522502d5a6ea217ea133d9 > > Hmm, the detail of an SPBA issue is sometimes complicated due to > different fabric designs between SoCs. We cannot simply say that > a DMA access for an IP under the Shared Peripheral Bus requires > SPBA clock or not unless the hardware team clearly demands that. > > However, as an arbiter, the SPBA must be outside any of those IPs > and tied to the SDMA in order to balancing memory access between > the SDMA and a co-existing CPU. The question is whether we treat > it as a part of an IP wrapper or a part of the SDMA. > > Therefore, unless a CPU access would fail even *without any SDMA > access being launched*, it sounds fair to me to put it into the > DMA code. I discussed this issue with IC team. The SPBA bus has 3 master port, one is for SDMA, one is for MCU (ARM core), the third one is for DSP ( currently there is no connection for DSP). Any two master port are used simultaneously, there will be arbitration issue when SPBA clock is not enabled. So I think it is better put SPBA clock in Audio IP, because if there is DSP master port + MCU master used, there will be issue too. (DSP master port is not used in i.MX chip). Anyway I think put it in SDMA driver is not good choice, if SDMA is removed, there will be still issue. Put it in Audio IP maybe more safe. _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
