linux-kernel - [PATCH 3/6] memory: brcmstb: dpfe: wait for DCPU to be ready

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Date:   Tue,  2 Apr 2019 16:01:00 -0700
From:   Markus Mayer <code@...yer.net>
To:     Brian Norris <computersforpeace@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Gregory Fong <gregory.0xf0@...il.com>
Cc:     Markus Mayer <mmayer@...adcom.com>,
        Broadcom Kernel List <bcm-kernel-feedback-list@...adcom.com>,
        ARM Kernel List <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 3/6] memory: brcmstb: dpfe: wait for DCPU to be ready

From: Markus Mayer <mmayer@...adcom.com>

We wait for the DCPU to be ready before sending a command.

Signed-off-by: Markus Mayer <mmayer@...adcom.com>
---
 drivers/memory/brcmstb_dpfe.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/memory/brcmstb_dpfe.c b/drivers/memory/brcmstb_dpfe.c
index c67774a4fe8b..f8d05a8266c3 100644
--- a/drivers/memory/brcmstb_dpfe.c
+++ b/drivers/memory/brcmstb_dpfe.c
@@ -304,6 +304,18 @@ static int __send_command(struct private_data *priv, unsigned int cmd,
 
 	mutex_lock(&priv->lock);
 
+	/* Wait for DCPU to become ready */
+	for (i = 0; i < DELAY_LOOP_MAX; i++) {
+		resp = readl_relaxed(regs + REG_TO_HOST_MBOX);
+		if (resp == 0)
+			break;
+		msleep(1);
+	}
+	if (resp != 0) {
+		mutex_unlock(&priv->lock);
+		return -ETIMEDOUT;
+	}
+
 	/* Write command and arguments to message area */
 	for (i = 0; i < MSG_FIELD_MAX; i++)
 		writel_relaxed(msg[i], regs + DCPU_MSG_RAM(i));
-- 
2.17.1