Re: [PATCH v2 5/9] mailbox: imx: Start splitting the IRQ handler in primary and threaded handler

[Peng Fan <peng.fan@oss.nxp.com>]

On Wed, Jun 03, 2026 at 03:05:08PM +0200, Sebastian Andrzej Siewior wrote:
>Split the mailbox irq handling into a primary handler (imx_mu_isr()) and
>a threaded handler (imx_mu_isr_th()). The primary handler masks the
>interrupt event so the threaded handler can run without raising the
>interrupt again. The threaded handler can invoke the actuall callback in
>preemtible context.
>
>As a first step, prepare the logic and move TX handling part.
>
>Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
>---
> drivers/mailbox/imx-mailbox.c | 33 ++++++++++++++++++++++++++++++---
> 1 file changed, 30 insertions(+), 3 deletions(-)
>
>diff --git a/drivers/mailbox/imx-mailbox.c b/drivers/mailbox/imx-mailbox.c
>index d1de07cc0ed62..006aa76b74b62 100644
>--- a/drivers/mailbox/imx-mailbox.c
>+++ b/drivers/mailbox/imx-mailbox.c
>@@ -81,6 +81,7 @@ struct imx_mu_con_priv {
> 	struct mbox_chan	*chan;
> 	struct work_struct 	txdb_work;
> 	bool			shutdown;
>+	bool			pending;
> };
> 
> struct imx_mu_priv {
>@@ -539,11 +540,35 @@ static void imx_mu_txdb_work(struct work_struct *t)
> 	mbox_chan_txdone(cp->chan, 0);
> }
> 
>+static irqreturn_t imx_mu_isr_th(int irq, void *p)
>+{
>+	struct mbox_chan *chan = p;
>+	struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
>+	struct imx_mu_con_priv *cp = chan->con_priv;
>+
>+	if (!cp->pending)
>+		return IRQ_NONE;

Is there a chance that cp->pending could be false here?

Regards
Peng

>+
>+	switch (cp->type) {
>+	case IMX_MU_TYPE_TX:
>+		cp->pending = false;
>+		mbox_chan_txdone(chan, 0);
>+		break;
>+
>+	default:
>+		dev_warn_ratelimited(priv->dev, "Unhandled channel type %d\n",
>+				     cp->type);
>+		return IRQ_NONE;
>+	}
>+	return IRQ_HANDLED;
>+}
>+
> static irqreturn_t imx_mu_isr(int irq, void *p)
> {
> 	struct mbox_chan *chan = p;
> 	struct imx_mu_priv *priv = to_imx_mu_priv(chan->mbox);
> 	struct imx_mu_con_priv *cp = chan->con_priv;
>+	irqreturn_t ret = IRQ_HANDLED;
> 	u32 val, ctrl;
> 
> 	switch (cp->type) {
>@@ -579,7 +604,8 @@ static irqreturn_t imx_mu_isr(int irq, void *p)
> 	if ((val == IMX_MU_xSR_TEn(priv->dcfg->type, cp->idx)) &&
> 	    (cp->type == IMX_MU_TYPE_TX)) {
> 		imx_mu_xcr_rmw(priv, IMX_MU_TCR, 0, IMX_MU_xCR_TIEn(priv->dcfg->type, cp->idx));
>-		mbox_chan_txdone(chan, 0);
>+		cp->pending = true;
>+		ret = IRQ_WAKE_THREAD;
> 	} else if ((val == IMX_MU_xSR_RFn(priv->dcfg->type, cp->idx)) &&
> 		   (cp->type == IMX_MU_TYPE_RX)) {
> 		priv->dcfg->rx(priv, cp);
>@@ -594,7 +620,7 @@ static irqreturn_t imx_mu_isr(int irq, void *p)
> 	if (priv->suspend)
> 		pm_system_wakeup();
> 
>-	return IRQ_HANDLED;
>+	return ret;
> }
> 
> static int imx_mu_send_data(struct mbox_chan *chan, void *data)
>@@ -629,7 +655,8 @@ static int imx_mu_startup(struct mbox_chan *chan)
> 	if (!(priv->dcfg->type & IMX_MU_V2_IRQ))
> 		irq_flag |= IRQF_SHARED;
> 
>-	ret = request_irq(priv->irq[cp->type], imx_mu_isr, irq_flag, cp->irq_desc, chan);
>+	ret = request_threaded_irq(priv->irq[cp->type], imx_mu_isr, imx_mu_isr_th,
>+				   irq_flag, cp->irq_desc, chan);
> 	if (ret) {
> 		dev_err(priv->dev, "Unable to acquire IRQ %d\n", priv->irq[cp->type]);
> 		return ret;
>
>-- 
>2.53.0
>