| Message ID | 20210322105538.3475183-2-i.uvarov@cognitivepilot.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | add devicetree for Forlinx FETA40i-C & OKA40i-C | expand |
On Mon, 22 Mar 2021 13:55:35 +0300 Ivan Uvarov <i.uvarov@cognitivepilot.com> wrote: Hi, > This patch adds the /omit-if-no-ref/ keyword to the pio nodes for > UART0 and UART3 pins of the R40 SoC, which would reduce the fdt size on > boards which do not use these UARTs. But what boards are those? It seems like all boards use uart3-pg and the two existing boards use UART0. I think the idea is to use omit-if-no-ref on some rarely used nodes, so if there is only a single user, for instance. Your next patch is a good example. So I don't think this patch here is needed at all. Cheers, Andre > > Signed-off-by: Ivan Uvarov <i.uvarov@cognitivepilot.com> > > 1 file changed, 3 insertions(+) > > diff --git a/arch/arm/boot/dts/sun8i-r40.dtsi b/arch/arm/boot/dts/sun8i-r40.dtsi > index d5ad3b9efd..0b257a0779 100644 > --- a/arch/arm/boot/dts/sun8i-r40.dtsi > +++ b/arch/arm/boot/dts/sun8i-r40.dtsi > @@ -631,16 +631,19 @@ spi1_cs1_pi_pin: spi1-cs1-pi-pin { > function = "spi1"; > }; > > + /omit-if-no-ref/ > uart0_pb_pins: uart0-pb-pins { > pins = "PB22", "PB23"; > function = "uart0"; > }; > > + /omit-if-no-ref/ > uart3_pg_pins: uart3-pg-pins { > pins = "PG6", "PG7"; > function = "uart3"; > }; > > + /omit-if-no-ref/ > uart3_rts_cts_pg_pins: uart3-rts-cts-pg-pins { > pins = "PG8", "PG9"; > function = "uart3";
On Mon, 22 Mar 2021 16:18:04 +0000 Andre Przywara <andre.przywara@arm.com> wrote: > On Mon, 22 Mar 2021 13:55:35 +0300 > Ivan Uvarov <i.uvarov@cognitivepilot.com> wrote: > > Hi, > > > This patch adds the /omit-if-no-ref/ keyword to the pio nodes for > > UART0 and UART3 pins of the R40 SoC, which would reduce the fdt > > size on boards which do not use these UARTs. > > But what boards are those? It seems like all boards use uart3-pg and > the two existing boards use UART0. > > I think the idea is to use omit-if-no-ref on some rarely used nodes, > so if there is only a single user, for instance. Your next patch is a > good example. > > So I don't think this patch here is needed at all. > > Cheers, > Andre > This is a valid complaint, and the patch indeed is not strictly necessary. At the same time, the keyword certainly doesn't hurt, and it would be a good base for future R40 boards. As to what boards I'm referring to, there's at least the carrier board for the FETA40i which our company is privately developing, the support for which we probably won't upstream as it's highly unlikely it'll ever get into the hands of anyone who would appreciate such support. I must also mention that I only added this patch to the series due to explicit encouragement from Maxime in his last response to v1 of the patch: On Fri, 19 Mar 2021 14:24:48 +0100 Maxime Ripard <maxime@cerno.tech> wrote: > On Tue, Mar 16, 2021 at 06:48:58PM +0300, Ivan Uvarov wrote: > > Also, would it be a good idea to add /omit-if-no-ref/ to the uart3 > > pins as well while I'm here? > > To all the nodes honestly. If you want to make a preliminary patch doing > this, go ahead :) Since there's two differing viewpoints on the subject, this definitely deserves more discussion. -- Regards, Ivan Uvarov
On Mon, Mar 22, 2021 at 04:18:04PM +0000, Andre Przywara wrote: > On Mon, 22 Mar 2021 13:55:35 +0300 > Ivan Uvarov <i.uvarov@cognitivepilot.com> wrote: > > Hi, > > > This patch adds the /omit-if-no-ref/ keyword to the pio nodes for > > UART0 and UART3 pins of the R40 SoC, which would reduce the fdt size on > > boards which do not use these UARTs. > > But what boards are those? It seems like all boards use uart3-pg and > the two existing boards use UART0. > > I think the idea is to use omit-if-no-ref on some rarely used nodes, so > if there is only a single user, for instance. Your next patch is a good > example. There's no real cost associated to it though, so it's just easier to flag all the nodes and let the compiler figure out if it should evict them or not. Maxime
diff --git a/arch/arm/boot/dts/sun8i-r40.dtsi b/arch/arm/boot/dts/sun8i-r40.dtsi index d5ad3b9efd..0b257a0779 100644 --- a/arch/arm/boot/dts/sun8i-r40.dtsi +++ b/arch/arm/boot/dts/sun8i-r40.dtsi @@ -631,16 +631,19 @@ spi1_cs1_pi_pin: spi1-cs1-pi-pin { function = "spi1"; }; + /omit-if-no-ref/ uart0_pb_pins: uart0-pb-pins { pins = "PB22", "PB23"; function = "uart0"; }; + /omit-if-no-ref/ uart3_pg_pins: uart3-pg-pins { pins = "PG6", "PG7"; function = "uart3"; }; + /omit-if-no-ref/ uart3_rts_cts_pg_pins: uart3-rts-cts-pg-pins { pins = "PG8", "PG9"; function = "uart3";
This patch adds the /omit-if-no-ref/ keyword to the pio nodes for UART0 and UART3 pins of the R40 SoC, which would reduce the fdt size on boards which do not use these UARTs. Signed-off-by: Ivan Uvarov <i.uvarov@cognitivepilot.com> 1 file changed, 3 insertions(+)