Messages in this thread | | | From | "Balas, Eliza" <> | Subject | RE: [PATCH v3 2/2] drivers: misc: adi-axi-tdd: Add TDD engine | Date | Mon, 23 Oct 2023 12:54:15 +0000 |
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> -----Original Message----- > From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> > Sent: Friday, October 20, 2023 17:32 > To: Balas, Eliza <Eliza.Balas@analog.com> > Cc: linux-kernel@vger.kernel.org; devicetree@vger.kernel.org; Rob Herring <robh+dt@kernel.org>; Krzysztof Kozlowski > <krzysztof.kozlowski+dt@linaro.org>; Conor Dooley <conor+dt@kernel.org>; Derek Kiernan <derek.kiernan@amd.com>; Dragan > Cvetic <dragan.cvetic@amd.com>; Arnd Bergmann <arnd@arndb.de> > Subject: Re: [PATCH v3 2/2] drivers: misc: adi-axi-tdd: Add TDD engine > > [External] > > On Fri, Oct 20, 2023 at 11:18:44AM +0000, Balas, Eliza wrote: > > > > +static int adi_axi_tdd_parse_ms(struct adi_axi_tdd_state *st, > > > > + const char *buf, > > > > + u64 *res) > > > > +{ > > > > + u64 clk_rate = READ_ONCE(st->clk.rate); > > > > + char *orig_str, *modf_str, *int_part, frac_part[7]; > > > > + long ival, frac; > > > > + int ret; > > > > + > > > > + orig_str = kstrdup(buf, GFP_KERNEL); > > > > + int_part = strsep(&orig_str, "."); > > > > > > Why are we parsing floating point in the kernel? Please just keep the > > > api simple so that we don't have to try to do any type of parsing other > > > than turning a single text number into a value. > > > > > > > The adi_axi_tdd_parse_ms function does almost the same thing as the > > iio_str_to_fixpoint() function which already exists in kernel. > > That does not mean that this is a valid api for your device as you are > not an iio driver (why aren't you an iio driver?) > > > It parses a fixed-point number from a string. > > And as such, you shouldn't duplicate existing logic. > > > The __iio_str_to_fixpoint is used in a similar way, as I intend to use adi_axi_tdd_parse_ms. > > It writes to a channel the corresponding scale (micro,nano) for a value. > > Why not just have the api accept values in nanoseconds and then no > parsing is needed?
I thought this would be easier for the user, to work with smaller values, than using a lot of zeros for nanoseconds. I will make the changes to accept values in nanoseconds..
> > Since the device is not an iio device, using an iio function would be confusing. > > Why isn't this an iio device?
The device is not registered into the IIO device tree, and does not rely on IIO kernel APIs. Even though there are a few attributes that resemble the ones from iio, and the sysfs structure is similar, this is not an IIO device. In the previous patch versions 1 and 2 we concluded that this device fits better in the misc subsystem.
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