linux-kernel - [PATCH v2] auxdisplay: ht16k33: use le16_to

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Date:   Sat, 1 Apr 2017 10:27:14 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Robin van der Gracht <robin@...tonic.nl>
Cc:     Miguel Ojeda Sandonis <miguel.ojeda.sandonis@...il.com>,
        Arnd Bergmann <arnd@...db.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH v2] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data

The data read from the device is 3 little-endian words, so let's
annotate them as such and use le16_to_cpu() to convert them to host
endianness - it might turn out to be a bit more performant, and it
expresses the conversion more clearly.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
---
v2: do not compare result of i2c_smbus_read_i2c_block_data with
hard-coded value.

 drivers/auxdisplay/ht16k33.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c
index f66b45b235b0..73f966434a2e 100644
--- a/drivers/auxdisplay/ht16k33.c
+++ b/drivers/auxdisplay/ht16k33.c
@@ -254,18 +254,22 @@ static bool ht16k33_keypad_scan(struct ht16k33_keypad *keypad)
 {
 	const unsigned short *keycodes = keypad->dev->keycode;
 	u16 new_state[HT16K33_MATRIX_KEYPAD_MAX_COLS];
-	u8 data[HT16K33_MATRIX_KEYPAD_MAX_COLS * 2];
+	__le16 data[HT16K33_MATRIX_KEYPAD_MAX_COLS];
 	unsigned long bits_changed;
 	int row, col, code;
+	int rc;
 	bool pressed = false;
 
-	if (i2c_smbus_read_i2c_block_data(keypad->client, 0x40, 6, data) != 6) {
-		dev_err(&keypad->client->dev, "Failed to read key data\n");
+	rc = i2c_smbus_read_i2c_block_data(keypad->client, 0x40,
+					   sizeof(data), (u8 *)data);
+	if (rc != sizeof(data)) {
+		dev_err(&keypad->client->dev,
+			"Failed to read key data, rc=%d\n", rc);
 		return false;
 	}
 
 	for (col = 0; col < keypad->cols; col++) {
-		new_state[col] = (data[col * 2 + 1] << 8) | data[col * 2];
+		new_state[col] = le16_to_cpu(data[col]);
 		if (new_state[col])
 			pressed = true;
 		bits_changed = keypad->last_key_state[col] ^ new_state[col];
-- 
2.12.2.564.g063fe858b8-goog


-- 
Dmitry