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@freescale.com 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/...
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.