On Sat, Sep 4, 2021 at 9:51 AM Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote: > > On Fri, Sep 3, 2021 at 8:11 PM Rob Herring <robh@xxxxxxxxxx> wrote: > > > > On Fri, Sep 03, 2021 at 05:53:40PM +0300, Daniel Baluta wrote: > > > From: Daniel Baluta <daniel.baluta@xxxxxxx> > > > > > > DSP node on the Linux kernel side must also take care of enabling > > > DAI/DMA related clocks. > > > > > > By design we choose to manage DAI/DMA clocks from the kernel side because of > > > the architecture of some i.MX8 boards. > > > > > > Clocks are handled by a special M4 core which runs a special firmware > > > called SCFW (System Controler firmware). > > > > > > This communicates with A cores running Linux via a special Messaging > > > Unit and implements a custom API which is already implemented by the > > > Linux kernel i.MX clocks implementation. > > > > > > Note that these clocks are optional. We can use the DSP without them. > > > > > > Signed-off-by: Daniel Baluta <daniel.baluta@xxxxxxx> > > > --- > > > .../devicetree/bindings/dsp/fsl,dsp.yaml | 33 +++++++++++++++++++ > > > 1 file changed, 33 insertions(+) > > > > > > diff --git a/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml b/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml > > > index 7afc9f2be13a..1453668c0194 100644 > > > --- a/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml > > > +++ b/Documentation/devicetree/bindings/dsp/fsl,dsp.yaml > > > @@ -24,16 +24,49 @@ properties: > > > maxItems: 1 > > > > > > clocks: > > > + minItems: 3 > > > items: > > > - description: ipg clock > > > - description: ocram clock > > > - description: core clock > > > + - description: esai0 core clock for accessing registers > > > + - description: esai0 baud clock > > > + - description: esai0 system clock > > > + - description: esai0 spba clock required when ESAI is placed in slave mode > > > + - description: SAI1 bus clock > > > + - description: SAI1 master clock 0 > > > + - description: SAI1 master clock 1 > > > + - description: SAI1 master clock 2 > > > + - description: SAI1 master clock 3 > > > + - description: SAI3 bus clock > > > + - description: SAI3 master clock 0 > > > + - description: SAI3 master clock 1 > > > + - description: SAI3 master clock 2 > > > + - description: SAI3 master clock 3 > > > + - description: SDMA3 root clock used for accessing registers > > > > Sigh, I just rejected this kind of thing for the other i.MX8 DSP > > binding[1]. > > > > Add a reference to the h/w block and then get the clocks (and other > > resources) from there. > > The H/W block is controlled by the DSP firmware. So, we don't want > to use the Linux kernel driver (thus the H/W block device tree node). 'status' is how you disable a device to not be used by the OS. The information about that device's resources are already in DT, we don't need to duplicate that here. If you want a list of devices assigned to the DSP here, that would be okay. > The only thing that we cannot control from the DSP firmware are the clocks > hence we handle them in the DSP node. > > We moved the DAI clocks under the DSP node as I think you suggested here: > > https://www.lkml.org/lkml/2020/3/12/969 No, that's certainly not what I was suggesting. The resources in the DSP node should be the h/w resources of the DSP itself. Rob
