linux-kernel - [PATCH v1 5/7] auxdisplay: arm-charlcd: Use readl_poll

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Message-ID: <20251229142349.1251843-6-andriy.shevchenko@linux.intel.com>
Date: Mon, 29 Dec 2025 14:52:38 +0100
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Cc: Andy Shevchenko <andy@...nel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>
Subject: [PATCH v1 5/7] auxdisplay: arm-charlcd: Use readl_poll_timeout

Use readl_poll_timeout_atomic() from <iopoll.h> instead of using
custom poll loops.

The timeout settings are different, but that shouldn't be much of a
problem. Instead of polling 10 times in a close loop, it polls for
one millisecond.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
---
 drivers/auxdisplay/arm-charlcd.c | 24 +++++++-----------------
 1 file changed, 7 insertions(+), 17 deletions(-)

diff --git a/drivers/auxdisplay/arm-charlcd.c b/drivers/auxdisplay/arm-charlcd.c
index ac8604d3b9a0..a537126f5d6a 100644
--- a/drivers/auxdisplay/arm-charlcd.c
+++ b/drivers/auxdisplay/arm-charlcd.c
@@ -13,7 +13,7 @@
 #include <linux/err.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
-#include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/mod_devicetable.h>
 #include <linux/platform_device.h>
 #include <linux/string.h>
@@ -115,20 +115,14 @@ static u8 charlcd_4bit_read_char(struct charlcd *lcd)
 {
 	u8 data;
 	u32 val;
-	int i;
 
 	/* If we can, use an IRQ to wait for the data, else poll */
 	if (lcd->irq >= 0)
 		charlcd_wait_complete_irq(lcd);
 	else {
-		i = 0;
-		val = 0;
-		while (!(val & CHAR_RAW_VALID) && i < 10) {
-			udelay(100);
-			val = readl(lcd->virtbase + CHAR_RAW);
-			i++;
-		}
-
+		udelay(100);
+		readl_poll_timeout_atomic(lcd->virtbase + CHAR_RAW, val,
+					  val & CHAR_RAW_VALID, 100, 1000);
 		writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 	}
 	msleep(1);
@@ -140,13 +134,9 @@ static u8 charlcd_4bit_read_char(struct charlcd *lcd)
 	 * The second read for the low bits does not trigger an IRQ
 	 * so in this case we have to poll for the 4 lower bits
 	 */
-	i = 0;
-	val = 0;
-	while (!(val & CHAR_RAW_VALID) && i < 10) {
-		udelay(100);
-		val = readl(lcd->virtbase + CHAR_RAW);
-		i++;
-	}
+	udelay(100);
+	readl_poll_timeout_atomic(lcd->virtbase + CHAR_RAW, val,
+				  val & CHAR_RAW_VALID, 100, 1000);
 	writel(CHAR_RAW_CLEAR, lcd->virtbase + CHAR_RAW);
 	msleep(1);
 
-- 
2.50.1