On 22. 8. 2022, at 19:39, Mark Brown broonie@kernel.org wrote:
On Fri, Aug 19, 2022 at 02:54:29PM +0200, Martin Povišer wrote:
This all looks good, one style nit and a couple of requests for clarification below but basically this is fine.
+++ b/sound/soc/apple/mca.c @@ -0,0 +1,1149 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*
- Apple SoCs MCA driver
- Copyright (C) The Asahi Linux Contributors
- The MCA peripheral is made up of a number of identical units called clusters.
Please make the entire comment block a C++ one so things look more intentional.
Is this so that it does not look like the SPDX header was added mechanically? I will do it, just curious what the reasoning is.
+#define USE_RXB_FOR_CAPTURE
What's this all about?
There’s something we can configure one way or the other way in the hardware (choosing RXA or RXB unit in a cluster for capture). Since this driver developed along reverse-engineering the hardware, this switch got built in. I want to keep it for future experimentation. Also, as the driver’s side gig is documenting the hardware, this way it documents more.
+static int mca_fe_enable_clocks(struct mca_cluster *cl) +{
- struct mca_data *mca = cl->host;
- int ret;
- ret = clk_prepare_enable(cl->clk_parent);
- if (ret) {
dev_err(mca->dev,"cluster %d: unable to enable clock parent: %d\n",cl->no, ret);return ret;- }
- /*
* We can't power up the device earlier than this because* the power state driver would error out on seeing the device* as clock-gated.*/- cl->pd_link = device_link_add(mca->dev, cl->pd_dev,
DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME |DL_FLAG_RPM_ACTIVE);I'm not clear on this dynamically adding and removing device links stuff
- it looks like the main (only?) purpose is to take a runtime PM
reference to the target device which is fine but it's not clear why device links are involved given that the links are created and destroyed every time the DAI is used, AFAICT always in the same fixed relationship. It's not a problem, it's just unclear.
Indeed the only purpose is powering up the cluster’s power domain (there’s one domain for each cluster). Adding the links is the only way I know to do it. They need to be added dynamically (as opposed to statically linking, say, the DAI’s ->dev to the cluster’s ->pd_dev, which I guess may do something similar), because we need to sequence the power-up/power-down with the enablement of the clocks.
Martin