ASoC: SOF: imx: remove error checks on NULL ipc

imx_dsp_get_data() can return NULL, but the value is not checked
before being usd, leading to static analysis warnings.

sound/soc/sof/imx/imx8.c:85:3

ASoC: SOF: imx: remove error checks on NULL ipc

imx_dsp_get_data() can return NULL, but the value is not checked
before being usd, leading to static analysis warnings.

sound/soc/sof/imx/imx8.c:85:32: error: dereference of NULL ‘0’
[CWE-476] [-Werror=analyzer-null-dereference]

85 | spin_lock_irqsave(&priv->sdev->ipc_lock, flags);
| ~~~~^~~~~~

It appears this is not really a possible problem, so remove those checks.

Signed-off-by: Pierre-Louis Bossart <[email protected]>
Reviewed-by: Rander Wang <[email protected]>
Reviewed-by: Daniel Baluta <[email protected]>
Reviewed-by: Yaochun Hung <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

show more ...

firmware: imx-dsp: Export functions to request/free channels

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 f

firmware: imx-dsp: Export functions to request/free channels

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 <[email protected]>
Reviewed-by: Paul Olaru <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>

show more ...

firmware: imx: Add DSP IPC protocol interface

Some of i.MX8 processors (e.g i.MX8QM, i.MX8QXP) contain
the Tensilica HiFi4 DSP for advanced pre- and post-audio
processing.

The communication between

firmware: imx: Add DSP IPC protocol interface

Some of i.MX8 processors (e.g i.MX8QM, i.MX8QXP) contain
the Tensilica HiFi4 DSP for advanced pre- and post-audio
processing.

The communication between Host CPU and DSP firmware is
taking place using a shared memory area for message passing
and a dedicated Messaging Unit for notifications.

DSP IPC protocol offers a doorbell interface using
imx-mailbox API.

We use 4 MU channels (2 x TXDB, 2 x RXDB) to implement a
request-reply protocol.

Connection 0 (txdb0, rxdb0):
- Host writes messasge to shared memory [SHMEM]
- Host sends a request [MU]
- DSP handles request [SHMEM]
- DSP sends reply [MU]

Connection 1 (txdb1, rxdb1):
- DSP writes a message to shared memory [SHMEM]
- DSP sends a request [MU]
- Host handles request [SHMEM]
- Host sends reply [MU]

The protocol interface will be used by a Host client to
communicate with the DSP. First client will be the i.MX8
part from Sound Open Firmware infrastructure.

The protocol offers the following interface:

On Tx:
- imx_dsp_ring_doorbell, will be called to notify the DSP
that it needs to handle a request.

On Rx:
- clients need to provide two callbacks:
.handle_reply
.handle_request
- the callbacks will be used by the protocol on
notification arrival from DSP.

Signed-off-by: Daniel Baluta <[email protected]>
Reviewed-by: Oleksij Rempel <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>

show more ...