On Tue, Sep 24, 2024 at 12:16:27PM GMT, Maxime Ripard wrote:

On Tue, Sep 24, 2024 at 03:36:49PM GMT, Sandor Yu wrote:

quoted

+static int cdns_mhdp8501_read_hpd(struct cdns_mhdp8501_device *mhdp)
+{
+	u8 status;
+	int ret;
+
+	mutex_lock(&mhdp_mailbox_mutex);
+
+	ret = cdns_mhdp_mailbox_send(&mhdp->base, MB_MODULE_ID_GENERAL,
+				     GENERAL_GET_HPD_STATE, 0, NULL);
+	if (ret)
+		goto err_get_hpd;
+
+	ret = cdns_mhdp_mailbox_recv_header(&mhdp->base, MB_MODULE_ID_GENERAL,
+					    GENERAL_GET_HPD_STATE,
+					    sizeof(status));
+	if (ret)
+		goto err_get_hpd;
+
+	ret = cdns_mhdp_mailbox_recv_data(&mhdp->base, &status, sizeof(status));
+	if (ret)
+		goto err_get_hpd;
+
+	mutex_unlock(&mhdp_mailbox_mutex);

That's better I guess, but it's still not a good API design. If you
can't have concurrent accesses, then cdns_mhdp_mailbox_send et al.
should take the mutex themselves.

I think that a proper API might be:

int cdns_mhdp_mailbox_send_recv(struct cdns_mhdp_device *mhdp,
			u8 module_id, u8 opcode,
			u16 size, const u8 *message,
			u16 buf_size, u8 *buf);

Internally it should take the lock, exchange the data, then return.

-- 
With best wishes
Dmitry