From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiko =?ISO-8859-1?Q?St=FCbner?= Subject: Re: [PATCH] arm64: dts: rockchip: add spiX aliases for rk3399 Date: Wed, 20 Jul 2016 00:18:40 +0200 Message-ID: <1841177.NDa9D09EGz@diego> References: <1468545873-134339-1-git-send-email-briannorris@chromium.org> <20160719192754.GA140860@google.com> <20160719192912.GA142821@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20160719192912.GA142821@google.com> Sender: linux-kernel-owner@vger.kernel.org To: Brian Norris Cc: Uwe =?ISO-8859-1?Q?Kleine=2DK=F6nig?= , devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, Brian Norris , linux-arm-kernel@lists.infradead.org, Caesar Wang , Rob Herring List-Id: devicetree@vger.kernel.org Am Dienstag, 19. Juli 2016, 12:29:14 schrieb Brian Norris: > On Tue, Jul 19, 2016 at 12:27:54PM -0700, Brian Norris wrote: > > + Rob >=20 > + Rob for real >=20 > > Hi, > >=20 > > On Tue, Jul 19, 2016 at 08:56:47PM +0200, Heiko Stuebner wrote: > > > Am Dienstag, 19. Juli 2016, 08:39:55 schrieb Uwe Kleine-K=F6nig: > > > > On Thu, Jul 14, 2016 at 06:24:33PM -0700, Brian Norris wrote: > > > > > It's nicer to see this: > > > > > # ls -l /sys/bus/spi/devices/ > > > > > total 0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi0.0 -> > > > > > ../../../devices/platform/ff1c0000.spi/spi_master/spi0/sp= i0.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi1.0 -> > > > > > ../../../devices/platform/ff1d0000.spi/spi_master/spi1/sp= i1.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi2.0 -> > > > > > ../../../devices/platform/ff1e0000.spi/spi_master/spi2/sp= i2.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi5.0 -> > > > > > ../../../devices/platform/ff200000.spi/spi_master/spi5/sp= i5.0> > > > > >=20 > > > > > than this: > > > > > # ls -l /sys/bus/spi/devices/ > > > > > total 0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32763.0 -> > > > > > ../../../devices/platform/ff200000.spi/spi_master/spi3276= 3/spi32 > > > > > 763.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32764.0 -> > > > > > ../../../devices/platform/ff1e0000.spi/spi_master/spi3276= 4/spi32 > > > > > 764.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32765.0 -> > > > > > ../../../devices/platform/ff1d0000.spi/spi_master/spi3276= 5/spi32 > > > > > 765.0 > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32766.0 -> > > > > > ../../../devices/platform/ff1c0000.spi/spi_master/spi3276= 6/spi32 > > > > > 766.0> > > > > >=20 > > > > > With the latter, it's much clearer which bus devices are on. > > > > >=20 > > > > > Signed-off-by: Brian Norris > > > > > --- > > > > >=20 > > > > > arch/arm64/boot/dts/rockchip/rk3399.dtsi | 6 ++++++ > > > > > 1 file changed, 6 insertions(+) > > > > >=20 > > > > > diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi > > > > > b/arch/arm64/boot/dts/rockchip/rk3399.dtsi index > > > > > 4c84229789ef..b04abbfd4898 100644 > > > > > --- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi > > > > > +++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi > > > > > @@ -70,6 +70,12 @@ > > > > >=20 > > > > > serial2 =3D &uart2; > > > > > serial3 =3D &uart3; > > > > > serial4 =3D &uart4; > > > > >=20 > > > > > + spi0 =3D &spi0; > > > > > + spi1 =3D &spi1; > > > > > + spi2 =3D &spi2; > > > > > + spi3 =3D &spi3; > > > > > + spi4 =3D &spi4; > > > > > + spi5 =3D &spi5; > > > >=20 > > > > Note that Rob Herring (with his dt-maintainer hat on) doesn't l= ike > > > > these > > > > aliases. > > > >=20 > > > > See for example: > > > > http://mid.gmane.org/20160705140546.GA10601@rob-hp-laptop > >=20 > > But why? I believe half the arguments in the linked thread were > > Catch-22's -- there were no "mainline" users (which is a false targ= et > > IMO anyway, as Christer Weinigel mentioned somewhere in the thread = Rob > > linked), and so we couldn't accept more documentation (or users) fo= r the > > feature. FWIW, my quick grep now shows there are currently 43 mainl= ine > > users. > >=20 > > This feature is very useful. Some of the thread Rob pointed to argu= ed > > that the indexing isn't HW documentation; in this case, it most > > certainly is. The RK3399 TRM explicitly has these SPI buses named S= PI0, > > SPI1, SPI2, SPI3, SPI4, and SPI5, and schematics that I've seen use= the > > same terminology. It is therefore *much* nicer to have my device sh= ow up > > as 'spi2.0' (reflecting their correct HW name) rather than spi32764= =2E0. > > Sometimes I can't even get as far as mounting sysfs to check what t= his > > maps to, but having spi2.0 in the kernel log can clearly tell me wh= at > > device is causing problems. > >=20 > > If Rob can support a better alternative solution, I'd be happy to > > switch. But I don't understand why we can't use a useful (not just = to > > me, but presumably to at least 43 other independent users, and many > > more out of tree), existing, and long-supported feature here. Personally, I don't have any real opinion on this but the argument soun= ds=20 plausible to me (aka they are named with numbers in every manual, schem= atics)=20 so it might be helpful to have that around - similar to i2c that is in = the=20 dtsi already. I think I remember Doug having a similar discussion around mmc-aliases = some=20 time ago - that met opposition as well [0] - although I guess the numbe= ring=20 was a bit more arbitary there. I guess we'll just see what Rob says. Heiko [0] https://lkml.org/lkml/2016/4/29/610