linux-kernel - Re: [PATCH v4 3/7] can: bittiming: move bittiming calculation functions to calc

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Message-ID: <CAMZ6RqJqSG16fdRE5_uiOmqsDboBgQCanvVNGaG5ZUDwpVoYvA@mail.gmail.com>
Date:   Sat, 4 Jun 2022 21:56:23 +0900
From:   Vincent MAILHOL <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     linux-can@...r.kernel.org, linux-kernel@...r.kernel.org,
        Max Staudt <max@...as.org>,
        Oliver Hartkopp <socketcan@...tkopp.net>,
        netdev@...r.kernel.org
Subject: Re: [PATCH v4 3/7] can: bittiming: move bittiming calculation
 functions to calc_bittiming.c

On Sat. 4 June 2022 at 21:41, Marc Kleine-Budde <mkl@...gutronix.de> wrote:
> On 04.06.2022 21:21:01, Vincent MAILHOL wrote:
> > On Sat. 4 June 2022 at 20:25, Marc Kleine-Budde <mkl@...gutronix.de> wrote:
> > > On 03.06.2022 19:28:44, Vincent Mailhol wrote:
> > > > The canonical way to select or deselect an object during compilation
> > > > is to use this pattern in the relevant Makefile:
> > > >
> > > > bar-$(CONFIG_FOO) := foo.o
> > > >
> > > > bittiming.c instead uses some #ifdef CONFIG_CAN_CALC_BITTIMG.
> > > >
> > > > Create a new file named calc_bittiming.c with all the functions which
> > > > are conditionally compiled with CONFIG_CAN_CALC_BITTIMG and modify the
> > > > Makefile according to above pattern.
> > > >
> > > > Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
> > > > ---
> > > >  drivers/net/can/Kconfig              |   4 +
> > > >  drivers/net/can/dev/Makefile         |   2 +
> > > >  drivers/net/can/dev/bittiming.c      | 197 --------------------------
> > > >  drivers/net/can/dev/calc_bittiming.c | 202 +++++++++++++++++++++++++++
> > > >  4 files changed, 208 insertions(+), 197 deletions(-)
> > > >  create mode 100644 drivers/net/can/dev/calc_bittiming.c
> > > >
> > > > diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
> > > > index b1e47f6c5586..8f3b97aea638 100644
> > > > --- a/drivers/net/can/Kconfig
> > > > +++ b/drivers/net/can/Kconfig
> > > > @@ -96,6 +96,10 @@ config CAN_CALC_BITTIMING
> > > >         source clock frequencies. Disabling saves some space, but then the
> > > >         bit-timing parameters must be specified directly using the Netlink
> > > >         arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw".
> > > > +
> > > > +       The additional features selected by this option will be added to the
> > > > +       can-dev module.
> > > > +
> > > >         If unsure, say Y.
> > > >
> > > >  config CAN_AT91
> > > > diff --git a/drivers/net/can/dev/Makefile b/drivers/net/can/dev/Makefile
> > > > index 919f87e36eed..b8a55b1d90cd 100644
> > > > --- a/drivers/net/can/dev/Makefile
> > > > +++ b/drivers/net/can/dev/Makefile
> > > > @@ -9,3 +9,5 @@ can-dev-$(CONFIG_CAN_NETLINK) += dev.o
> > > >  can-dev-$(CONFIG_CAN_NETLINK) += length.o
> > > >  can-dev-$(CONFIG_CAN_NETLINK) += netlink.o
> > > >  can-dev-$(CONFIG_CAN_NETLINK) += rx-offload.o
> > > > +
> > > > +can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
> > >
> > > Nitpick:
> > > Can we keep this list sorted?
> >
> > My idea was first to group per CONFIG symbol according to the
> > different levels: CAN_DEV first, then CAN_NETLINK and finally
> > CAN_CALC_BITTIMING and CAN_RX_OFFLOAD. And then only sort by
> > alphabetical order within each group.
>
> I was thinking to order by CONFIG symbol and put the objects without an
> additional symbol first
>
> > By sorting the list, do literally mean to sort each line like this:
> >
> > obj-$(CONFIG_CAN_DEV) += can-dev.o
> > can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
> > can-dev-$(CONFIG_CAN_DEV) += skb.o
> > can-dev-$(CONFIG_CAN_NETLINK) += bittiming.o
> > can-dev-$(CONFIG_CAN_NETLINK) += dev.o
> > can-dev-$(CONFIG_CAN_NETLINK) += length.o
> > can-dev-$(CONFIG_CAN_NETLINK) += netlink.o
> > can-dev-$(CONFIG_CAN_RX_OFFLOAD) += rx-offload.o
>
> ...which results in:
>
> obj-$(CONFIG_CAN_DEV) += can-dev.o
>
> can-dev-y += skb.o

I see. But this contradicts the idea to do
| obj-y += can-dev
as suggested in:
https://lore.kernel.org/linux-can/20220604112707.z4zjdjydqy5rkyfe@pengutronix.de/

So, we have to choose between:
| obj-$(CONFIG_CAN_DEV) += can-dev.o
|
| can-dev-y += skb.o
|
| can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
| (...)

or:

| obj-y += can-dev.o
|
| can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
| can-dev-$(CONFIG_CAN_DEV) += skb.o
| (...)

I have a slight preference for the second, but again, wouldn't mind to
select the first one.

> can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
> can-dev-$(CONFIG_CAN_NETLINK) += bittiming.o
> can-dev-$(CONFIG_CAN_NETLINK) += dev.o
> can-dev-$(CONFIG_CAN_NETLINK) += length.o
> can-dev-$(CONFIG_CAN_NETLINK) += netlink.o
> can-dev-$(CONFIG_CAN_RX_OFFLOAD) += rx-offload.o
>
> > or do you mean to sort by object name (ignoring the config symbol) like that:
> >
> > obj-$(CONFIG_CAN_DEV) += can-dev.o
> > can-dev-$(CONFIG_CAN_NETLINK) += bittiming.o
> > can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
> > can-dev-$(CONFIG_CAN_NETLINK) += dev.o
> > can-dev-$(CONFIG_CAN_NETLINK) += length.o
> > can-dev-$(CONFIG_CAN_NETLINK) += netlink.o
> > can-dev-$(CONFIG_CAN_RX_OFFLOAD) += rx-offload.o
> > can-dev-$(CONFIG_CAN_DEV) += skb.o
> >
> > ?
> >
> > (I honestly do not care so much how we sort the lines. My logic of
> > grouping first by CONFIG symbols seems more natural, but I am fine to
> > go with any other suggestion).
>
> I think this makes it clear where new files should be added.
>
> Marc
>
> --
> Pengutronix e.K.                 | Marc Kleine-Budde           |
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