In order to save power, we only need to request a channel
when the communication with the DSP active.
For this we export the following functions:
- imx_dsp_request_channel, gets a channel with a given index
- imx_dsp_free_channel, frees a channel with a given index
Notice that we still request channels at probe to support devices
that do not have PM callbacks implemented.
More explanations about why requesting a channel has an effect
on power savings:
- requesting an mailbox channel will call mailbox's startup
function.
- startup function calls pm_runtime_get_sync which increments device
usage count and will keep the device active. Specifically, mailbox
clock will be always ON when a mailbox channel is requested.
Signed-off-by: Daniel Baluta <daniel.bal...@nxp.com>
---
drivers/firmware/imx/imx-dsp.c | 25 +++++++++++++++++++++++++
include/linux/firmware/imx/dsp.h | 10 ++++++++++
2 files changed, 35 insertions(+)
diff --git a/drivers/firmware/imx/imx-dsp.c b/drivers/firmware/imx/imx-dsp.c
index b6e95d6d34c0..a6c06d7476c3 100644
--- a/drivers/firmware/imx/imx-dsp.c
+++ b/drivers/firmware/imx/imx-dsp.c
@@ -60,6 +60,31 @@ static void imx_dsp_handle_rx(struct mbox_client *c, void
*msg)
}
}
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
+{
+ struct imx_dsp_chan *dsp_chan;
+
+ if (idx >= DSP_MU_CHAN_NUM)
+ return ERR_PTR(-EINVAL);
+
+ dsp_chan = &dsp_ipc->chans[idx];
+ dsp_chan->ch = mbox_request_channel_byname(&dsp_chan->cl,
dsp_chan->name);
+ return dsp_chan->ch;
+}
+EXPORT_SYMBOL(imx_dsp_request_channel);
+
+void imx_dsp_free_channel(struct imx_dsp_ipc *dsp_ipc, int idx)
+{
+ struct imx_dsp_chan *dsp_chan;
+
+ if (idx >= DSP_MU_CHAN_NUM)
+ return;
+
+ dsp_chan = &dsp_ipc->chans[idx];
+ mbox_free_channel(dsp_chan->ch);
+}
+EXPORT_SYMBOL(imx_dsp_free_channel);
+
static int imx_dsp_setup_channels(struct imx_dsp_ipc *dsp_ipc)
{
struct device *dev = dsp_ipc->dev;
diff --git a/include/linux/firmware/imx/dsp.h b/include/linux/firmware/imx/dsp.h
index 7562099c9e46..4f7895a3b73c 100644
--- a/include/linux/firmware/imx/dsp.h
+++ b/include/linux/firmware/imx/dsp.h
@@ -55,6 +55,9 @@ static inline void *imx_dsp_get_data(struct imx_dsp_ipc *ipc)
int imx_dsp_ring_doorbell(struct imx_dsp_ipc *dsp, unsigned int chan_idx);
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx);
+void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx);
+
#else
static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc *ipc,
@@ -63,5 +66,12 @@ static inline int imx_dsp_ring_doorbell(struct imx_dsp_ipc
*ipc,
return -ENOTSUPP;
}
+struct mbox_chan *imx_dsp_request_channel(struct imx_dsp_ipc *ipc, int idx)
+{
+ return ERR_PTR(-EOPNOTSUPP);
+}
+
+void imx_dsp_free_channel(struct imx_dsp_ipc *ipc, int idx) { }
+
#endif
#endif /* _IMX_DSP_IPC_H */
--
2.17.1
