[PATCH v2 3/3] remoteproc: imx_dsp_rproc: Wait for suspend ACK only if WAIT_FW_CONFIRMATION is set

[Iuliana Prodan (OSS)]

From: Iuliana Prodan <iuliana.prodan at nxp.com>

The DSP suspend path currently waits unconditionally for a suspend ack
from the firmware. This breaks firmwares that do not implement the
mailbox-based CONFIRMATION handshake, as the DSP never responds and
system suspend fails with -EBUSY.

The driver already uses the WAIT_FW_CONFIRMATION flag to indicate that
the firmware supports the CONFIRMATION handshake at boot. Apply the same
logic during suspend: only send the suspend message and wait for the
suspend ack when the firmware is expected to support it.

Signed-off-by: Iuliana Prodan <iuliana.prodan at nxp.com>
---
Changes since v1:
- Moved confirmation check earlier to avoid sending the message when
FEATURE_SKIP_FW_CONFIRMATION is set, since RP_MBOX_SUSPEND_SYSTEM is
not handled on the remote side.
---
 drivers/remoteproc/imx_dsp_rproc.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/remoteproc/imx_dsp_rproc.c b/drivers/remoteproc/imx_dsp_rproc.c
index 1f3a35756769..d03017d6b214 100644
--- a/drivers/remoteproc/imx_dsp_rproc.c
+++ b/drivers/remoteproc/imx_dsp_rproc.c
@@ -1251,6 +1251,12 @@ static int imx_dsp_suspend(struct device *dev)
 		goto out;
 	}
 
+	/* No fw confirmation expected, so trigger PM runtime suspend */
+	if (!(priv->flags & WAIT_FW_CONFIRMATION)) {
+		dev_dbg(dev, "No FW_CONFIRMATION needed, suspend directly.\n");
+		goto out;
+	}
+
 	reinit_completion(&priv->pm_comp);
 
 	/* Tell DSP that suspend is happening */
-- 
2.25.1