From: Robin van der Gracht <robin@protonic.nl>
To: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Miguel Ojeda Sandonis <miguel.ojeda.sandonis@gmail.com>,
Arnd Bergmann <arnd@arndb.de>, Rob Herring <robh@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Linus Walleij <linus.walleij@linaro.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data
Date: Wed, 29 Mar 2017 10:13:59 +0200 [thread overview]
Message-ID: <20170329101359.3d928ff8@erd979> (raw)
In-Reply-To: <20170329074208.GA20429@dtor-ws>
On Wed, 29 Mar 2017 00:42:08 -0700
Dmitry Torokhov <dmitry.torokhov@gmail.com> 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 <dmitry.torokhov@gmail.com>
> ---
> 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
next prev parent reply other threads:[~2017-03-29 8:14 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-29 7:42 [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data Dmitry Torokhov
2017-03-29 8:13 ` Robin van der Gracht [this message]
2017-04-01 17:24 ` Dmitry Torokhov
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20170329101359.3d928ff8@erd979 \
--to=robin@protonic.nl \
--cc=arnd@arndb.de \
--cc=dmitry.torokhov@gmail.com \
--cc=gregkh@linuxfoundation.org \
--cc=linus.walleij@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=miguel.ojeda.sandonis@gmail.com \
--cc=robh@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).