On Mon, 2022-02-14 at 15:49 +0200, Andy Shevchenko wrote: > On Mon, Feb 07, 2022 at 09:19:46PM +0100, Nuno Sá wrote: > > On Mon, 2022-02-07 at 13:09 +0200, Andy Shevchenko wrote: > > > On Sun, Feb 06, 2022 at 01:19:59PM +0000, Sa, Nuno wrote: > > > > > From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> > > > > > Sent: Saturday, February 5, 2022 6:30 PM > > > > > On Fri, Jan 21, 2022 at 03:24:59PM +0100, Nuno Sá wrote: > > ... > > > > > > Second, why do you need this specific function instead of > > > > > regmap > > > > > bulk > > > > > ops against be24/le24? > > > > > > > > Not sure I'm following this one... If you mean why am I using a > > > > custom > > > > regmap_bus implementation, that was already explained in the > > > > RFC > > > > patch. > > > > And IIRC, you were the one already asking 😉. > > > > > > Hmm... It was some time I have looked there. Any message ID to > > > share, > > > so > > > I can find it quickly? > > > https://lore.kernel.org/all/20211112152235.12fdcc49@jic23-huawei/ > > Thanks! > > So, it's all about cs_change, right? > But doesn't bulk operation work exactly as we need here? > Yes... that and we need to send the NOOP command in the second TX transfer. > Looking again to the RFC code, it seems like we can still do it > > First, you call _gather_write() followed by _read(). It will show > exactly what > you do, i.e. you send command first with the value 0x0000, followed > by sending > command and reading back the value at the same time. > > Would it work? Well, _gather_write() are 2 spi transfers only with TX set. That means that only on the _read() (which will be another spi_message) we will ask for the data. Im not really sure this would work being it on a different message. This would also mean, one extra dummy transfer. To me that already feels that a custom bus implementation is not a bad idea... > > ... > > > > > > > + ret = kstrtou16(buf, 10, &val); > > > > > > > > > > In other function you have long, here u16. I would expect > > > > > that > > > > > the > > > > > types are of > > > > > the same class, e.g. if here you have u16, then there > > > > > something > > > > > like > > > > > s32 / s64. > > > > > Or here something like unsigned short. > > > > > > > > > > A bit of elaboration why u16 is chosen here? > > > > > > > > Well, I never really saw any enforcement here to be honest > > > > (rather > > > > than using > > > > stdint types...). So I pretty much just use these in unsigned > > > > types > > > > because > > > > I'm lazy and u16 is faster to type than unsigned short... In > > > > this > > > > case, unless Jonathan > > > > really asks for it, I prefer not to go all over the driver and > > > > change this... > > > > > > This is about consistency. It may work as is, but it feels not > > > good > > > when for > > > int (or unsigned int) one uses fixed-width types. Also it's non- > > > written advice > > > to use fixed-width variables when it's about programming > > > registers or > > > so, for > > > the rest, use POD types. > Ok, going a bit back in the discussion, you argued that in one place I was using long while here u16. Well, in the place I'm using long, that was on purpose because that value is to be compared against an array of longs (which has to be long because it depends on CCF rates). I guess I can als0 use s64, but there is also a reason why long was used. In the u16 case, we really want to have 2 bytes because I'm going to use that value to write the dac code which is 2 bytes. > > I can understand your reasoning but again this is something that > > I never really saw being enforced. So, I'm more than ok to change > > it > > if it really becomes something that we will try to "enforce" in > > IIO. > > Otherwise it just feels as a random nitpick :). > > No, this is about consistency and common sense. If you define type > uXX, > we have an API for that exact type. It's confusing why POD type APIs > are used with fixed-width types or vise versa. > > Moreover (which is pure theoretical, though) some architectures might > have no (mutual) equivalency between these types. > > ... > > > > > > > +static int ltc2688_tgp_clk_setup(struct ltc2688_state *st, > > > > > > + struct ltc2688_chan *chan, > > > > > > + struct device_node *np, > > > > > > int > > > > > > tgp) > > > > > > +{ > > > > > > + unsigned long rate; > > > > > > + struct clk *clk; > > > > > > + int ret, f; > > > > > > + > > > > > > + clk = devm_get_clk_from_child(&st->spi->dev, np, > > > > > > NULL); > > > > > > + if (IS_ERR(clk)) > > > > > > > > > > Make it optional for non-OF, can be done as easy as > > > > > > > > > > if (IS_ERR(clk)) { > > > > > if (PTR_ERR(clk) == -ENOENT) > > > > > clk = NULL; > > > > > else > > > > > return dev_err_probe(...); > > > > > } > > > > > > > > > > > + return dev_err_probe(&st->spi->dev, > > > > > > PTR_ERR(clk), > > > > > > + "failed to get tgp > > > > > > clk.\n"); > > > > > > > > Well, I might be missing the point but I think this is not so > > > > straight.... > > > > We will only get here if the property " adi,toggle-dither- > > > > input" is > > > > given > > > > in which case having the associated clocks is __mandatory__. > > > > > > Ah, okay, would be a limitation for non-OF platforms. > > > > > > > Hence, > > > > once we are here, this can never be optional. That said, we > > > > need > > > > device_node > > > > > > That's fine, since CCF is OF-centric API. > > > > > > > and hence of.h > > > > > > Why? This header doesn't bring anything you will use here. > > > > Correct me if Im missing something. AFAIU, the idea is to use > > 'device_for_each_child_node()' which returns a fwnode_handle. That > > means, that we will have to pass that to this function and use > > 'to_of_node()' to pass a device_node to > > 'devm_get_clk_from_child()'. > > > > This means, we need of.h for 'to_of_node()'... > > Yeah, you are right, but it would be still better since it narrows > the problem to the CCF calls only. > So, to clear.... In your opinion, you are fine whith using device properties and just have 'to_of_node()' in this CCF call? I'm fine with it, so if Jonathan does not have any complain about it, will do like this in v4, Jonathan, any comment on this one? - Nuno Sá
