linux-kernel - [PATCH] gpio: aspeed: Don't attempt to debounce if disabled

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Message-Id: <20170502060824.6457-1-joel@jms.id.au>
Date:   Tue,  2 May 2017 15:38:24 +0930
From:   Joel Stanley <joel@....id.au>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andrew Jeffery <andrew@...id.au>
Subject: [PATCH] gpio: aspeed: Don't attempt to debounce if disabled

We warn the user at driver probe time that debouncing is disabled.
However, if they request debouncing later on we print a confusing error
message:

 gpio_aspeed 1e780000.gpio: Failed to convert 5000us to cycles at 0Hz: -524

Instead bail out when the clock is not present.

Fixes: 5ae4cb94b3133 (gpio: aspeed: Add debounce support)
Signed-off-by: Joel Stanley <joel@....id.au>
---
 drivers/gpio/gpio-aspeed.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpio/gpio-aspeed.c b/drivers/gpio/gpio-aspeed.c
index ccea609676ee..4ca436e66bdb 100644
--- a/drivers/gpio/gpio-aspeed.c
+++ b/drivers/gpio/gpio-aspeed.c
@@ -646,6 +646,9 @@ static int enable_debounce(struct gpio_chip *chip, unsigned int offset,
 	int rc;
 	int i;
 
+	if (!gpio->clk)
+		return -EINVAL;
+
 	rc = usecs_to_cycles(gpio, usecs, &requested_cycles);
 	if (rc < 0) {
 		dev_warn(chip->parent, "Failed to convert %luus to cycles at %luHz: %d\n",
-- 
2.11.0