Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752120AbdDARYd (ORCPT ); Sat, 1 Apr 2017 13:24:33 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:35430 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751661AbdDARYa (ORCPT ); Sat, 1 Apr 2017 13:24:30 -0400 Date: Sat, 1 Apr 2017 10:24:27 -0700 From: Dmitry Torokhov To: Robin van der Gracht 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: <20170401172427.GL17130@dtor-ws> References: <20170329074208.GA20429@dtor-ws> <20170329101359.3d928ff8@erd979> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170329101359.3d928ff8@erd979> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1953 Lines: 58 On Wed, Mar 29, 2017 at 10:13:59AM +0200, Robin van der Gracht wrote: > 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? It was quite late into the night ;) V2 is coming. > > > 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 -- Dmitry