Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754769AbdC2IOT (ORCPT ); Wed, 29 Mar 2017 04:14:19 -0400 Received: from protonic.xs4all.nl ([83.163.252.89]:24519 "EHLO protonic.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754603AbdC2IOQ (ORCPT ); Wed, 29 Mar 2017 04:14:16 -0400 Date: Wed, 29 Mar 2017 10:13:59 +0200 From: Robin van der Gracht To: Dmitry Torokhov Cc: Miguel Ojeda Sandonis , Arnd Bergmann , Rob Herring , Greg Kroah-Hartman , Linus Walleij , linux-kernel@vger.kernel.org Subject: Re: [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data Message-ID: <20170329101359.3d928ff8@erd979> In-Reply-To: <20170329074208.GA20429@dtor-ws> References: <20170329074208.GA20429@dtor-ws> Organization: Protonic Holland X-Mailer: Claws Mail 3.14.0 (GTK+ 2.24.30; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1717 Lines: 51 On Wed, 29 Mar 2017 00:42:08 -0700 Dmitry Torokhov wrote: > 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. Agreed > > Signed-off-by: Dmitry Torokhov > --- > drivers/auxdisplay/ht16k33.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/auxdisplay/ht16k33.c b/drivers/auxdisplay/ht16k33.c > index f66b45b235b0..61af52a7afd5 100644 > --- a/drivers/auxdisplay/ht16k33.c > +++ b/drivers/auxdisplay/ht16k33.c > @@ -254,18 +254,19 @@ 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; > bool pressed = false; > > - if (i2c_smbus_read_i2c_block_data(keypad->client, 0x40, 6, data) != 6) { > + if (i2c_smbus_read_i2c_block_data(keypad->client, 0x40, > + sizeof(data), (u8 *)data) != 6) { Why use sizeof(data) for length but check against the hardcoded 6? > dev_err(&keypad->client->dev, "Failed to read key data\n"); > 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]); nice! > if (new_state[col]) > pressed = true; > bits_changed = keypad->last_key_state[col] ^ new_state[col]; Robin