Messages in this thread | | | Date | Mon, 22 Aug 2022 11:03:03 +0200 | From | Paul Cercueil <> | Subject | Re: [PATCH 4/4] input: joystick: Fix buffer data parsing |
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Hi Jonathan,
Le ven., août 19 2022 at 18:53:39 +0100, Jonathan Cameron <jic23@kernel.org> a écrit : > On Wed, 17 Aug 2022 12:56:43 +0200 > Artur Rojek <contact@artur-rojek.eu> wrote: > >> Don't try to access buffer data of a channel by its scan index. >> Instead, >> use the newly introduced `iio_find_channel_offset_in_buffer` to get >> the >> correct data offset. >> >> The scan index of a channel does not represent its position in a >> buffer, >> as the buffer will contain data for enabled channels only, affecting >> data offsets and alignment. >> >> Fixes: 2c2b364fddd5 ("Input: joystick - add ADC attached joystick >> driver.") >> Reported-by: Chris Morgan <macromorgan@hotmail.com> >> Tested-by: Paul Cercueil <paul@crapouillou.net> >> Signed-off-by: Artur Rojek <contact@artur-rojek.eu> >> --- >> drivers/input/joystick/adc-joystick.c | 26 >> +++++++++++++++++--------- >> 1 file changed, 17 insertions(+), 9 deletions(-) >> >> diff --git a/drivers/input/joystick/adc-joystick.c >> b/drivers/input/joystick/adc-joystick.c >> index c0deff5d4282..aed853ebe1d1 100644 >> --- a/drivers/input/joystick/adc-joystick.c >> +++ b/drivers/input/joystick/adc-joystick.c >> @@ -6,6 +6,7 @@ >> #include <linux/ctype.h> >> #include <linux/input.h> >> #include <linux/iio/iio.h> >> +#include <linux/iio/buffer.h> >> #include <linux/iio/consumer.h> >> #include <linux/module.h> >> #include <linux/platform_device.h> >> @@ -46,36 +47,43 @@ static void adc_joystick_poll(struct input_dev >> *input) >> static int adc_joystick_handle(const void *data, void *private) >> { >> struct adc_joystick *joy = private; >> + struct iio_buffer *buffer; >> enum iio_endian endianness; >> - int bytes, msb, val, idx, i; >> - const u16 *data_u16; >> + int bytes, msb, val, off; >> + const u8 *chan_data; >> + unsigned int i; >> bool sign; >> >> bytes = joy->chans[0].channel->scan_type.storagebits >> 3; >> >> for (i = 0; i < joy->num_chans; ++i) { >> - idx = joy->chans[i].channel->scan_index; >> endianness = joy->chans[i].channel->scan_type.endianness; >> msb = joy->chans[i].channel->scan_type.realbits - 1; >> sign = tolower(joy->chans[i].channel->scan_type.sign) == 's'; >> + buffer = iio_channel_cb_get_iio_buffer(joy->buffer); >> + off = iio_find_channel_offset_in_buffer(joy->chans[i].indio_dev, >> + joy->chans[i].channel, >> + buffer); > > With this call replaced with one that instead uses > > off = iio_find_channel_offset_in_buffer(joy->chans, i); > > which I'm fairly sure is enough via the info in chans[x]->channel to > establish this offset. > > All is good, though you should probably cache it as doing that maths > every > time seems excessive. > > >> + if (off < 0) >> + return off; >> + >> + chan_data = (const u8 *)data + off; >> >> switch (bytes) { >> case 1: >> - val = ((const u8 *)data)[idx]; >> + val = *chan_data; >> break; >> case 2: >> - data_u16 = (const u16 *)data + idx; >> - >> /* >> * Data is aligned to the sample size by IIO core. >> * Call `get_unaligned_xe16` to hide type casting. >> */ >> if (endianness == IIO_BE) >> - val = get_unaligned_be16(data_u16); >> + val = get_unaligned_be16(chan_data); > > I obviously missed this previously but these are aligned so we don't > need the > unaligned form.
Yes, the comment above says that it's used to hide type casting.
Cheers, -Paul
>> else if (endianness == IIO_LE) >> - val = get_unaligned_le16(data_u16); >> + val = get_unaligned_le16(chan_data); >> else /* IIO_CPU */ >> - val = *data_u16; >> + val = *(const u16 *)chan_data; >> break; >> default: >> return -EINVAL; >
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