-----Original Message-----
From: Lucas Stach [mailto:l.stach at pengutronix.de]
Sent: Tuesday, July 24, 2018 1:20 AM
To: Oleksij Rempel <o.rempel@pengutronix.de>; Shawn Guo
[off-list ref]; Fabio Estevam [off-list ref]; Rob
Herring [off-list ref]; Mark Rutland [off-list ref]; A.s.
Dong [off-list ref]; Vladimir Zapolskiy
[off-list ref]
Cc: dl-linux-imx <redacted>; linux-arm-kernel at lists.infradead.org;
kernel at pengutronix.de; devicetree at vger.kernel.org
Subject: Re: [PATCH v6 5/5] mailbox: Add support for i.MX7D messaging unit

[...]

quoted

+}
+
+static int imx_mu_send_data(struct mbox_chan *chan, void *data) {

quoted

+	struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
+	struct imx_mu_con_priv *cp = chan->con_priv;
+	u32 *arg = data;

+

quoted

+	if (!imx_mu_last_tx_done(chan))
+		return -EBUSY;

+

quoted

+	imx_mu_write(priv, *arg, IMX_MU_xTRn(cp->idx));

+	imx_mu_rmw(priv, IMX_MU_xCR, IMX_MU_xSR_TEn(cp->idx), 0);

In multi-channel mode this RMW cycle needs some kind of locking. As this
register is also changed from the irq handler, this probably needs to be a
irqsave spinlock.

Good catch!
They do need to be protected.

Regards
Dong Aisheng