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Message-ID: <3484113.eKHnDqRbfE@diego> Date: Wed, 20 Jul 2016 10:11:11 +0200 From: Heiko Stübner <heiko@...ech.de> To: Brian Norris <briannorris@...omium.org> Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>, devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-rockchip@...ts.infradead.org, Brian Norris <computersforpeace@...il.com>, linux-arm-kernel@...ts.infradead.org, Caesar Wang <wxt@...k-chips.com>, Rob Herring <robh+dt@...nel.org> Subject: Re: [PATCH] arm64: dts: rockchip: add spiX aliases for rk3399 Am Mittwoch, 20. Juli 2016, 00:18:40 schrieb Heiko Stübner: > 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 > > > > + Rob for real > > > > > Hi, > > > > > > On Tue, Jul 19, 2016 at 08:56:47PM +0200, Heiko Stuebner wrote: > > > > Am Dienstag, 19. Juli 2016, 08:39:55 schrieb Uwe Kleine-König: > > > > > 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/spi0.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi1.0 -> > > > > > > ../../../devices/platform/ff1d0000.spi/spi_master/spi1/spi1.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi2.0 -> > > > > > > ../../../devices/platform/ff1e0000.spi/spi_master/spi2/spi2.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi5.0 -> > > > > > > ../../../devices/platform/ff200000.spi/spi_master/spi5/spi5.0> > > > > > > > > > > > > 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/spi32763/spi > > > > > > 32 > > > > > > 763.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32764.0 -> > > > > > > ../../../devices/platform/ff1e0000.spi/spi_master/spi32764/spi > > > > > > 32 > > > > > > 764.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32765.0 -> > > > > > > ../../../devices/platform/ff1d0000.spi/spi_master/spi32765/spi > > > > > > 32 > > > > > > 765.0 > > > > > > lrwxrwxrwx 1 root root 0 Dec 31 1969 spi32766.0 -> > > > > > > ../../../devices/platform/ff1c0000.spi/spi_master/spi32766/spi > > > > > > 32 > > > > > > 766.0> > > > > > > > > > > > > With the latter, it's much clearer which bus devices are on. > > > > > > > > > > > > Signed-off-by: Brian Norris <briannorris@...omium.org> > > > > > > --- > > > > > > > > > > > > arch/arm64/boot/dts/rockchip/rk3399.dtsi | 6 ++++++ > > > > > > 1 file changed, 6 insertions(+) > > > > > > > > > > > > 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 @@ > > > > > > > > > > > > serial2 = &uart2; > > > > > > serial3 = &uart3; > > > > > > serial4 = &uart4; > > > > > > > > > > > > + spi0 = &spi0; > > > > > > + spi1 = &spi1; > > > > > > + spi2 = &spi2; > > > > > > + spi3 = &spi3; > > > > > > + spi4 = &spi4; > > > > > > + spi5 = &spi5; > > > > > > > > > > Note that Rob Herring (with his dt-maintainer hat on) doesn't like > > > > > these > > > > > aliases. > > > > > > > > > > See for example: > > > > > http://mid.gmane.org/20160705140546.GA10601@rob-hp-laptop > > > > > > But why? I believe half the arguments in the linked thread were > > > Catch-22's -- there were no "mainline" users (which is a false target > > > IMO anyway, as Christer Weinigel mentioned somewhere in the thread Rob > > > linked), and so we couldn't accept more documentation (or users) for the > > > feature. FWIW, my quick grep now shows there are currently 43 mainline > > > users. > > > > > > This feature is very useful. Some of the thread Rob pointed to argued > > > that the indexing isn't HW documentation; in this case, it most > > > certainly is. The RK3399 TRM explicitly has these SPI buses named SPI0, > > > 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 show up > > > as 'spi2.0' (reflecting their correct HW name) rather than spi32764.0. > > > Sometimes I can't even get as far as mounting sysfs to check what this > > > maps to, but having spi2.0 in the kernel log can clearly tell me what > > > device is causing problems. > > > > > > 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 sounds > plausible to me (aka they are named with numbers in every manual, > schematics) so it might be helpful to have that around - similar to i2c > that is in the dtsi already. > > I think I remember Doug having a similar discussion around mmc-aliases some > time ago - that met opposition as well [0] - although I guess the numbering > was a bit more arbitary there. > > I guess we'll just see what Rob says. Uwe pointed me to a very similar discussion and response from Rob about spi aliases at: https://lkml.org/lkml/2016/5/25/566
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