* [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data
@ 2017-03-29 7:42 Dmitry Torokhov
2017-03-29 8:13 ` Robin van der Gracht
0 siblings, 1 reply; 3+ messages in thread
From: Dmitry Torokhov @ 2017-03-29 7:42 UTC (permalink / raw)
To: Robin van der Gracht, Miguel Ojeda Sandonis
Cc: Arnd Bergmann, Rob Herring, Greg Kroah-Hartman, Linus Walleij,
linux-kernel
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@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) {
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]);
if (new_state[col])
pressed = true;
bits_changed = keypad->last_key_state[col] ^ new_state[col];
--
2.12.2.564.g063fe858b8-goog
--
Dmitry
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data
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
2017-04-01 17:24 ` Dmitry Torokhov
0 siblings, 1 reply; 3+ messages in thread
From: Robin van der Gracht @ 2017-03-29 8:13 UTC (permalink / raw)
To: Dmitry Torokhov
Cc: Miguel Ojeda Sandonis, Arnd Bergmann, Rob Herring,
Greg Kroah-Hartman, Linus Walleij, linux-kernel
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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] auxdisplay: ht16k33: use le16_to_cpup() to fetch LE16 data
2017-03-29 8:13 ` Robin van der Gracht
@ 2017-04-01 17:24 ` Dmitry Torokhov
0 siblings, 0 replies; 3+ messages in thread
From: Dmitry Torokhov @ 2017-04-01 17:24 UTC (permalink / raw)
To: Robin van der Gracht
Cc: Miguel Ojeda Sandonis, Arnd Bergmann, Rob Herring,
Greg Kroah-Hartman, Linus Walleij, linux-kernel
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 <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?
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
^ permalink raw reply [flat|nested] 3+ messages in thread
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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
2017-04-01 17:24 ` Dmitry Torokhov
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