On Wed, Oct 5, 2016 at 5:17 AM, Alison Schofield <amsfield22@xxxxxxxxx> wrote: > On Wed, Oct 05, 2016 at 03:17:22AM +0530, sayli karnik wrote: >> On Mon, Oct 3, 2016 at 10:46 PM, Alison Schofield <amsfield22@xxxxxxxxx> wrote: >> > On Mon, Oct 03, 2016 at 07:07:39PM +0530, sayli karnik wrote: >> >> On Mon, Oct 3, 2016 at 4:55 AM, Alison Schofield <amsfield22@xxxxxxxxx> wrote: >> >> > On Sun, Oct 02, 2016 at 05:53:08PM +0200, Lars-Peter Clausen wrote: >> >> >> On 10/02/2016 07:00 AM, Alison Schofield wrote: >> >> >> [...] >> >> >> >> --- >> >> >> >> drivers/iio/imu/bmi160/bmi160_core.c | 3 ++- >> >> >> >> 1 file changed, 2 insertions(+), 1 deletion(-) >> >> >> >> >> >> >> >> diff --git a/drivers/iio/imu/bmi160/bmi160_core.c b/drivers/iio/imu/bmi160/bmi160_core.c >> >> >> >> index e0251b8..5355507 100644 >> >> >> >> --- a/drivers/iio/imu/bmi160/bmi160_core.c >> >> >> >> +++ b/drivers/iio/imu/bmi160/bmi160_core.c >> >> >> >> @@ -398,7 +398,8 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p) >> >> >> >> struct iio_poll_func *pf = p; >> >> >> >> struct iio_dev *indio_dev = pf->indio_dev; >> >> >> >> struct bmi160_data *data = iio_priv(indio_dev); >> >> >> >> - s16 buf[16]; /* 3 sens x 3 axis x s16 + 3 x s16 pad + 4 x s16 tstamp */ >> >> >> >> + __le16 buf[16]; >> >> >> >> + /* 3 sens x 3 axis x __le16 + 3 x __le16 pad + 4 x __le16 tstamp */ >> >> >> >> int i, ret, j = 0, base = BMI160_REG_DATA_MAGN_XOUT_L; >> >> >> >> __le16 sample; >> >> >> > >> >> >> > Wondering about this option below. Data was read into an __le16, so that >> >> >> > was good diligence on drivers part. Seems we can use le16_to_cpu() for the >> >> >> > conversion into the buf. >> >> >> > >> >> >> > --- a/drivers/iio/imu/bmi160/bmi160_core.c >> >> >> > +++ b/drivers/iio/imu/bmi160/bmi160_core.c >> >> >> > @@ -408,7 +408,7 @@ static irqreturn_t bmi160_trigger_handler(int irq, void *p) >> >> >> > &sample, sizeof(__le16)); >> >> >> > if (ret < 0) >> >> >> > goto done; >> >> >> > - buf[j++] = sample; >> >> >> > + buf[j++] = le16_to_cpu(sample); >> >> >> > } >> >> >> >> >> >> This conversion is usually skipped on purpose and delayed until it is >> >> >> actually needed by the user. The IIO channel is accordingly marked that it >> >> >> will produce LE data. >> >> > Thanks Lars. I knew that for buffers, overlooked it, now I'll know it >> >> > better! >> >> > >> >> > So, Sayli, you probably got this from the analysis of the last patch. >> >> > In buffered mode, we'll go ahead and return the data in it's 'native' >> >> > order. So, my suggestion to convert it here, is wrong. Ignore ;) >> >> > >> >> Oh I see! So should I resend the patch with an updated >> >> description?(cosmetic/bug fix) >> > >> > Yes. In the commit message, you can leave out the subdirs (imu: bmc160:) >> > so that you have more space for a descriptive message of the change. >> >> A quick question about this being a bug fix or not. This would have >> worked fine on little endian systems. But wouldn't the byte order have >> changed in case of a big endian buffer, when the little endian samples >> are stored in it? >> If not, then this will be a cosmetic patch. >> >> thanks, >> sayli > > Hi Sayli, > Pulling linux-iio back in. Once we've started group thread, we need to > keep replying to 'all'. It helps those invested in this particular > patch, and also helps those who search in the future with similar > issues. > > To answer your question. I say cosmetic, because the le16 is going > into a 16bit buf element, and is labelled as IIO_LE in the channel > buffer definition. That's why Lars was saying we don't need to do > any conversion. We'll pass the bits as they came in, and tell the > readers of the buf that they are in little endian format. (And, also > note we weren't truncating any as was the case in your first endian fix.) > Noted! > OK - having said that, I stare at this code more, and wonder why > we are even bothering to label the sample as __le16, and whether > we should just label it as s16. Oh, in that case we could make both buf and sample s16. Also, I'm wondering about the use > of sizeof(). Shouldn't we be saying sizeof(sample) not sizeof(__le16)? > It's not a checkpatch error, but I feel like I've seen coccichecks > or coccinelle script patches repairing these misuses of sizeof > Yes sizeof(variable) instead of sizeof(type) makes code resistant to future type changes. > See what you think, group reply with questions, and we'll get to the > bottom of this one soon! > > Thanks, > alisons > -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
