On Mon, Apr 04, 2022 at 08:30:51AM +0200, Andrea Merello wrote: > Il giorno lun 28 mar 2022 alle ore 15:02 Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> ha scritto: > > > > On Sun, Mar 27, 2022 at 05:11:04PM +0100, Jonathan Cameron wrote: > > > On Tue, 22 Mar 2022 11:27:14 +0100 > > > Andrea Merello <andrea.merello@xxxxxxxxx> wrote: > > > > > > > Il giorno sab 19 feb 2022 alle ore 18:34 Jonathan Cameron > > > > <jic23@xxxxxxxxxx> ha scritto: > > > > > > > > > > On Thu, 17 Feb 2022 22:58:14 +0100 (CET) > > > > > Peter Meerwald-Stadler <pmeerw@xxxxxxxxxx> wrote: > > > > > > > > > > > On Thu, 17 Feb 2022, Andrea Merello wrote: > > > > > > > > > > > > nice work, minor comments below > > > > > > > > > > I'll review on top of Peter to save on duplication. > > > > > > > > > > Mostly really minor stuff. > > > > > > +CC Greg for binary attribute questions. > > > > > > > > > > > :) > > > > > > > > As usual, comments inline; OK for all the rest. > > > > > > > > > Given this has crossed with the introduction of namespaces to quite > > > > > a few IIO drivers (I have another series to do on that once I get > > > > > caught up with reviews) I'd prefer it if you would move this into > > > > > a symbol namespace (EXPORT_SYMBOL_NS_GPL() and appropriate namespace > > > > > statements in the two bus modules. > > > > > > > > > > Save it being done as a follow up series. If you prefer not to then > > > > > that's fine too as it'll be a trivial follow up patch. > > > > > > > > I'll include it in V4 directly. > > > > > > > > [...] > > > > > > > > > > > + case IIO_CHAN_INFO_SCALE: > > > > > > > + /* Table 3-31: 1 quaternion = 2^14 LSB */ > > > > > > > + if (size < 2) > > > > > > > + return -EINVAL; > > > > > > > + vals[0] = 1; > > > > > > > + vals[1] = 1 << 14; > > > > > > > + return IIO_VAL_FRACTIONAL_LOG2; > > > > > > > > > > This doesn't look right. Not vals[1] = 14 given FRACTIONAL_LOG2? > > > > > > > > Hum.. maybe just IIO_VAL_FRACTIONAL ? > > > > > > That works as well, though I'd argue FRACTIONAL_LOG2 is the > > > better option as it makes it clear the divisor is a power of 2 > > > and the precision might potentially be better as a result (I've not > > > checked!) > > > > > > > > > > > > > > + default: > > > > > > > + return -EINVAL; > > > > > > > + } > > > > > > > +} > > > > > > > + > > > > > > > > [...] > > > > > > > > > > > +static IIO_DEVICE_ATTR_RO(sys_calibration_auto_status, 0); > > > > > > > +static IIO_DEVICE_ATTR_RO(in_accel_calibration_auto_status, 0); > > > > > > > +static IIO_DEVICE_ATTR_RO(in_gyro_calibration_auto_status, 0); > > > > > > > +static IIO_DEVICE_ATTR_RO(in_magn_calibration_auto_status, 0); > > > > > > > +static IIO_DEVICE_ATTR_RO(calibration_data, 0); > > > > > > > > > > This is documented as providing binary data but it's not using > > > > > a binary attribute and that rather surprised me. > > > > > > > > > > Off the top of my head I can't recall why it matters though, so please > > > > > take a look at whether a bin_attribute makes more sense for this. > > > > > > > > As far as I can see, it seems that a non-binary attributes only > > > > support to be read at once while the binary attributes read() > > > > operation supports random access i.e. it has the file position > > > > parameter. > > > > > > > > The calibration data is "dynamic", it's read from the HW every time, > > > > and I'm not sure it makes any sense to read it in several chunks (what > > > > if we read a chunk and the calibration data is updated by the HW > > > > before reading the second chunk?). So, despide the fitting "binary" > > > > name I'm tempted to stick with regular attribute. However I'm not sure > > > > this is the only difference related to binary attributes. > > > > > > +Cc Greg. Valid choice to use a normal attribute for this? > > > > binary attributes are to ONLY be used for data that flows to/from a > > device without the kernel ever modifying the data at all. The kerneln > > is just a pass-through here. > > > > There are a few minor exceptions, but they were exceptions, please don't > > use them as a valid reason to use a binary attribute. > > > > does that help? > > Thanks. Here the driver doesn't modify the data, so no probl here about this. > > Would it be valid to restrict usage to only complete reads from the > start to the end on calibration data i.e. returning -EINVAL when > read() function is called with pos != 0 or count < actual data size ? That's up to you.
