| Message ID | 20170314075830.2247-1-zajec5@gmail.com |
|---|---|
| State | New |
| Headers | show |
On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: > From: Rafa?? Mi??ecki <rafal@milecki.pl> > > This adds baud rate, parity & number of data bits. It's required to get > serial working correctly. > > Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> > --- > arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi > index 8fd1ef9f0c2d..468107166a6f 100644 > --- a/arch/arm/boot/dts/bcm5301x.dtsi > +++ b/arch/arm/boot/dts/bcm5301x.dtsi > @@ -18,8 +18,12 @@ > / { > interrupt-parent = <&gic>; > > + aliases { > + serial0 = &uart0; > + }; > + > chosen { > - stdout-path = &uart0; > + stdout-path = "serial0:115200n8"; > }; Hi Rafal The alias is fine. But putting the stdout-path here is unusual. Which serial port is used for console is board specific, where as bcm5301x.dtsi is very generic, it describes the SoC, not a board. If you look at other .dtsi files, those that specify stdout-path contain properties which are common to a range of similar boards. Andrew
On 03/14/2017 01:26 PM, Andrew Lunn wrote: > On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >> From: Rafa?? Mi??ecki <rafal@milecki.pl> >> >> This adds baud rate, parity & number of data bits. It's required to get >> serial working correctly. >> >> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >> --- >> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >> 1 file changed, 5 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi >> index 8fd1ef9f0c2d..468107166a6f 100644 >> --- a/arch/arm/boot/dts/bcm5301x.dtsi >> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >> @@ -18,8 +18,12 @@ >> / { >> interrupt-parent = <&gic>; >> >> + aliases { >> + serial0 = &uart0; >> + }; >> + >> chosen { >> - stdout-path = &uart0; >> + stdout-path = "serial0:115200n8"; >> }; > > Hi Rafal > > The alias is fine. But putting the stdout-path here is unusual. Which > serial port is used for console is board specific, where as > bcm5301x.dtsi is very generic, it describes the SoC, not a board. If > you look at other .dtsi files, those that specify stdout-path contain > properties which are common to a range of similar boards. So far I've never seen any board using other uart. Also uart0 is disabled by default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / BCM47094). I think it's just more practical to have simple DTS that covers 99,9% boards by default and handled that margin of devices separately. We already got a lot of duplicated code for enabling uart0, see: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd Jon Mason from Broadcom who knows this hardware and designs very well confirmed it's a sane/safe assumption.
On 03/14/2017 01:32 PM, Rafał Miłecki wrote: > On 03/14/2017 01:26 PM, Andrew Lunn wrote: >> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >>> From: Rafa?? Mi??ecki <rafal@milecki.pl> >>> >>> This adds baud rate, parity & number of data bits. It's required to get >>> serial working correctly. >>> >>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >>> --- >>> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi >>> index 8fd1ef9f0c2d..468107166a6f 100644 >>> --- a/arch/arm/boot/dts/bcm5301x.dtsi >>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >>> @@ -18,8 +18,12 @@ >>> / { >>> interrupt-parent = <&gic>; >>> >>> + aliases { >>> + serial0 = &uart0; >>> + }; >>> + >>> chosen { >>> - stdout-path = &uart0; >>> + stdout-path = "serial0:115200n8"; >>> }; >> >> Hi Rafal >> >> The alias is fine. But putting the stdout-path here is unusual. Which >> serial port is used for console is board specific, where as >> bcm5301x.dtsi is very generic, it describes the SoC, not a board. If >> you look at other .dtsi files, those that specify stdout-path contain >> properties which are common to a range of similar boards. > > So far I've never seen any board using other uart. Also uart0 is disabled by > default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / > BCM47094). I think it's just more practical to have simple DTS that covers > 99,9% boards by default and handled that margin of devices separately. > > We already got a lot of duplicated code for enabling uart0, see: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd > > Jon Mason from Broadcom who knows this hardware and designs very well confirmed > it's a sane/safe assumption. That was supposed to be "any other uart or parameters".
> >The alias is fine. But putting the stdout-path here is unusual. Which > >serial port is used for console is board specific, where as > >bcm5301x.dtsi is very generic, it describes the SoC, not a board. If > >you look at other .dtsi files, those that specify stdout-path contain > >properties which are common to a range of similar boards. > > So far I've never seen any board using other uart. Also uart0 is disabled by > default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / > BCM47094). I think it's just more practical to have simple DTS that covers > 99,9% boards by default and handled that margin of devices separately. > > We already got a lot of duplicated code for enabling uart0, see: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd > > Jon Mason from Broadcom who knows this hardware and designs very well confirmed > it's a sane/safe assumption. I don't disagree with you, it does make sense. But it is just different to every other SoC .dtsi file Linux has. And we try to avoid things being different. It is down to Florian to decide, as maintainer. Andrew
On Tue, Mar 14, 2017 at 8:32 AM, Rafał Miłecki <zajec5@gmail.com> wrote: > On 03/14/2017 01:26 PM, Andrew Lunn wrote: >> >> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >>> >>> From: Rafa?? Mi??ecki <rafal@milecki.pl> >>> >>> This adds baud rate, parity & number of data bits. It's required to get >>> serial working correctly. >>> >>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >>> --- >>> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >>> 1 file changed, 5 insertions(+), 1 deletion(-) >>> >>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi >>> b/arch/arm/boot/dts/bcm5301x.dtsi >>> index 8fd1ef9f0c2d..468107166a6f 100644 >>> --- a/arch/arm/boot/dts/bcm5301x.dtsi >>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >>> @@ -18,8 +18,12 @@ >>> / { >>> interrupt-parent = <&gic>; >>> >>> + aliases { >>> + serial0 = &uart0; >>> + }; >>> + >>> chosen { >>> - stdout-path = &uart0; >>> + stdout-path = "serial0:115200n8"; >>> }; >> >> >> Hi Rafal >> >> The alias is fine. But putting the stdout-path here is unusual. Which >> serial port is used for console is board specific, where as >> bcm5301x.dtsi is very generic, it describes the SoC, not a board. If >> you look at other .dtsi files, those that specify stdout-path contain >> properties which are common to a range of similar boards. > > > So far I've never seen any board using other uart. Also uart0 is disabled by > default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / > BCM47094). I think it's just more practical to have simple DTS that covers > 99,9% boards by default and handled that margin of devices separately. > > We already got a lot of duplicated code for enabling uart0, see: > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd > > Jon Mason from Broadcom who knows this hardware and designs very well > confirmed > it's a sane/safe assumption. It should work for all the boards. The question is whether it should be in the DTSI or DTS file. This code replicates code I have in arch/arm/boot/dts/bcm953012k.dts So, either it should be removed or we should change all of the other DTS files to have this entry. My understanding is that the latter approach is the acceptable one (which matches Andrew's comment), but I can make the other changes if necessary. Thanks, Jon
On 17-03-14 07:53 AM, Jon Mason wrote: > On Tue, Mar 14, 2017 at 8:32 AM, Rafał Miłecki <zajec5@gmail.com> wrote: >> On 03/14/2017 01:26 PM, Andrew Lunn wrote: >>> >>> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >>>> >>>> From: Rafa?? Mi??ecki <rafal@milecki.pl> >>>> >>>> This adds baud rate, parity & number of data bits. It's required to get >>>> serial working correctly. >>>> >>>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >>>> --- >>>> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi >>>> b/arch/arm/boot/dts/bcm5301x.dtsi >>>> index 8fd1ef9f0c2d..468107166a6f 100644 >>>> --- a/arch/arm/boot/dts/bcm5301x.dtsi >>>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >>>> @@ -18,8 +18,12 @@ >>>> / { >>>> interrupt-parent = <&gic>; >>>> >>>> + aliases { >>>> + serial0 = &uart0; >>>> + }; >>>> + >>>> chosen { >>>> - stdout-path = &uart0; >>>> + stdout-path = "serial0:115200n8"; >>>> }; >>> >>> >>> Hi Rafal >>> >>> The alias is fine. But putting the stdout-path here is unusual. Which >>> serial port is used for console is board specific, where as >>> bcm5301x.dtsi is very generic, it describes the SoC, not a board. If >>> you look at other .dtsi files, those that specify stdout-path contain >>> properties which are common to a range of similar boards. >> >> >> So far I've never seen any board using other uart. Also uart0 is disabled by >> default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / >> BCM47094). I think it's just more practical to have simple DTS that covers >> 99,9% boards by default and handled that margin of devices separately. >> >> We already got a lot of duplicated code for enabling uart0, see: >> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd >> >> Jon Mason from Broadcom who knows this hardware and designs very well >> confirmed >> it's a sane/safe assumption. > > > It should work for all the boards. The question is whether it should > be in the DTSI or DTS file. This code replicates code I have in > arch/arm/boot/dts/bcm953012k.dts > So, either it should be removed or we should change all of the other > DTS files to have this entry. My understanding is that the latter > approach is the acceptable one (which matches Andrew's comment), but I > can make the other changes if necessary. dtsi file is fine to handle 99% of the use cases and not duplicate the entry. This is what we do for newer SoCs (such as Cygnus) where the console will always be a particular UART (as the BootROM already uses a certain UART the boards are designed to use that UART as the console always). For bcm953012 a similar situation exists as a common bootloader is used across boards. So, the uart used as the terminal will always be the same. I don't see a good reason for duplicating the code in every dts file. Acked-by: Scott Branden <scott.branden@broadcom.com> > > Thanks, > Jon >
On Tue, Mar 14, 2017 at 4:44 PM, Scott Branden <scott.branden@broadcom.com> wrote: > > > On 17-03-14 07:53 AM, Jon Mason wrote: >> >> On Tue, Mar 14, 2017 at 8:32 AM, Rafał Miłecki <zajec5@gmail.com> wrote: >>> >>> On 03/14/2017 01:26 PM, Andrew Lunn wrote: >>>> >>>> >>>> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >>>>> >>>>> >>>>> From: Rafa?? Mi??ecki <rafal@milecki.pl> >>>>> >>>>> This adds baud rate, parity & number of data bits. It's required to get >>>>> serial working correctly. >>>>> >>>>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >>>>> --- >>>>> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >>>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi >>>>> b/arch/arm/boot/dts/bcm5301x.dtsi >>>>> index 8fd1ef9f0c2d..468107166a6f 100644 >>>>> --- a/arch/arm/boot/dts/bcm5301x.dtsi >>>>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >>>>> @@ -18,8 +18,12 @@ >>>>> / { >>>>> interrupt-parent = <&gic>; >>>>> >>>>> + aliases { >>>>> + serial0 = &uart0; >>>>> + }; >>>>> + >>>>> chosen { >>>>> - stdout-path = &uart0; >>>>> + stdout-path = "serial0:115200n8"; >>>>> }; >>>> >>>> >>>> >>>> Hi Rafal >>>> >>>> The alias is fine. But putting the stdout-path here is unusual. Which >>>> serial port is used for console is board specific, where as >>>> bcm5301x.dtsi is very generic, it describes the SoC, not a board. If >>>> you look at other .dtsi files, those that specify stdout-path contain >>>> properties which are common to a range of similar boards. >>> >>> >>> >>> So far I've never seen any board using other uart. Also uart0 is disabled >>> by >>> default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / >>> BCM47094). I think it's just more practical to have simple DTS that >>> covers >>> 99,9% boards by default and handled that margin of devices separately. >>> >>> We already got a lot of duplicated code for enabling uart0, see: >>> >>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd >>> >>> Jon Mason from Broadcom who knows this hardware and designs very well >>> confirmed >>> it's a sane/safe assumption. >> >> >> >> It should work for all the boards. The question is whether it should >> be in the DTSI or DTS file. This code replicates code I have in >> arch/arm/boot/dts/bcm953012k.dts >> So, either it should be removed or we should change all of the other >> DTS files to have this entry. My understanding is that the latter >> approach is the acceptable one (which matches Andrew's comment), but I >> can make the other changes if necessary. > > dtsi file is fine to handle 99% of the use cases and not duplicate the > entry. This is what we do for newer SoCs (such as Cygnus) where the console > will always be a particular UART (as the BootROM already uses a certain UART > the boards are designed to use that UART as the console always). For > bcm953012 a similar situation exists as a common bootloader is used across > boards. So, the uart used as the terminal will always be the same. Unfortunately, there is not a common bootloader. CFE is used for the 4708/9 boards, and u-boot is used for the 5301x boards. Thanks, Jon > I don't see a good reason for duplicating the code in every dts file. > > Acked-by: Scott Branden <scott.branden@broadcom.com> >> >> >> Thanks, >> Jon >> >
On 17-03-14 02:18 PM, Jon Mason wrote: > On Tue, Mar 14, 2017 at 4:44 PM, Scott Branden > <scott.branden@broadcom.com> wrote: >> >> >> On 17-03-14 07:53 AM, Jon Mason wrote: >>> >>> On Tue, Mar 14, 2017 at 8:32 AM, Rafał Miłecki <zajec5@gmail.com> wrote: >>>> >>>> On 03/14/2017 01:26 PM, Andrew Lunn wrote: >>>>> >>>>> >>>>> On Tue, Mar 14, 2017 at 08:58:29AM +0100, Rafa?? Mi??ecki wrote: >>>>>> >>>>>> >>>>>> From: Rafa?? Mi??ecki <rafal@milecki.pl> >>>>>> >>>>>> This adds baud rate, parity & number of data bits. It's required to get >>>>>> serial working correctly. >>>>>> >>>>>> Signed-off-by: Rafa?? Mi??ecki <rafal@milecki.pl> >>>>>> --- >>>>>> arch/arm/boot/dts/bcm5301x.dtsi | 6 +++++- >>>>>> 1 file changed, 5 insertions(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/arch/arm/boot/dts/bcm5301x.dtsi >>>>>> b/arch/arm/boot/dts/bcm5301x.dtsi >>>>>> index 8fd1ef9f0c2d..468107166a6f 100644 >>>>>> --- a/arch/arm/boot/dts/bcm5301x.dtsi >>>>>> +++ b/arch/arm/boot/dts/bcm5301x.dtsi >>>>>> @@ -18,8 +18,12 @@ >>>>>> / { >>>>>> interrupt-parent = <&gic>; >>>>>> >>>>>> + aliases { >>>>>> + serial0 = &uart0; >>>>>> + }; >>>>>> + >>>>>> chosen { >>>>>> - stdout-path = &uart0; >>>>>> + stdout-path = "serial0:115200n8"; >>>>>> }; >>>>> >>>>> >>>>> >>>>> Hi Rafal >>>>> >>>>> The alias is fine. But putting the stdout-path here is unusual. Which >>>>> serial port is used for console is board specific, where as >>>>> bcm5301x.dtsi is very generic, it describes the SoC, not a board. If >>>>> you look at other .dtsi files, those that specify stdout-path contain >>>>> properties which are common to a range of similar boards. >>>> >>>> >>>> >>>> So far I've never seen any board using other uart. Also uart0 is disabled >>>> by >>>> default and we enable it per board family (BCM4708 / BCM47081 / BCM4709 / >>>> BCM47094). I think it's just more practical to have simple DTS that >>>> covers >>>> 99,9% boards by default and handled that margin of devices separately. >>>> >>>> We already got a lot of duplicated code for enabling uart0, see: >>>> >>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7b790d3b2943bf8e7e7bafe184008bd6451fe0bd >>>> >>>> Jon Mason from Broadcom who knows this hardware and designs very well >>>> confirmed >>>> it's a sane/safe assumption. >>> >>> >>> >>> It should work for all the boards. The question is whether it should >>> be in the DTSI or DTS file. This code replicates code I have in >>> arch/arm/boot/dts/bcm953012k.dts >>> So, either it should be removed or we should change all of the other >>> DTS files to have this entry. My understanding is that the latter >>> approach is the acceptable one (which matches Andrew's comment), but I >>> can make the other changes if necessary. >> >> dtsi file is fine to handle 99% of the use cases and not duplicate the >> entry. This is what we do for newer SoCs (such as Cygnus) where the console >> will always be a particular UART (as the BootROM already uses a certain UART >> the boards are designed to use that UART as the console always). For >> bcm953012 a similar situation exists as a common bootloader is used across >> boards. So, the uart used as the terminal will always be the same. > > Unfortunately, there is not a common bootloader. CFE is used for the > 4708/9 boards, and u-boot is used for the 5301x boards. OK, little different situation not having a boot rom with console output enforcing all designs to use the same UART. Do both of the bootloaders happen to use the same UART and all the boards are designed to use the same UART? > > Thanks, > Jon > >> I don't see a good reason for duplicating the code in every dts file. >> >> Acked-by: Scott Branden <scott.branden@broadcom.com> >>> >>> >>> Thanks, >>> Jon >>> >>
> >Unfortunately, there is not a common bootloader. CFE is used for the > >4708/9 boards, and u-boot is used for the 5301x boards. > OK, little different situation not having a boot rom with console > output enforcing all designs to use the same UART. > Do both of the bootloaders happen to use the same UART and all the > boards are designed to use the same UART? You need to be a little bit careful here. Some vendor could use a different UART in there design, use some other bootloader, etc. Somebody in the community might want to throw out uboot and use barebox etc.... Device tree does allow .dtsi properties to be over written, so it is not an issue in practice. Andrew
diff --git a/arch/arm/boot/dts/bcm5301x.dtsi b/arch/arm/boot/dts/bcm5301x.dtsi index 8fd1ef9f0c2d..468107166a6f 100644 --- a/arch/arm/boot/dts/bcm5301x.dtsi +++ b/arch/arm/boot/dts/bcm5301x.dtsi @@ -18,8 +18,12 @@ / { interrupt-parent = <&gic>; + aliases { + serial0 = &uart0; + }; + chosen { - stdout-path = &uart0; + stdout-path = "serial0:115200n8"; }; chipcommonA {