[PATCH] arm64: dts: qcom: msm8998-mtp: Add alias for blsp1_uart3

[PATCH] arm64: dts: qcom: msm8998-mtp: Add alias for blsp1_uart3

[Bjorn Andersson]

The msm_serial driver uses a simple counter to determine which port to
use when no alias is defined, but there's no logic to prevent this from
not colliding with what's defined by the aliases. As a result either
none or all of the active msm_serial instances must be listed as
aliases.

Define blsp1_uart3 as "serial1" to mitigate this problem.

Fixes: 4cffb9f2c700 ("arm64: dts: qcom: msm8998-mtp: Enable bluetooth")
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
 arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
index 5f101a20a20a..e08fcb426bbf 100644
--- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
@@ -9,6 +9,7 @@
 / {
 	aliases {
 		serial0 = &blsp2_uart1;
+		serial1 = &blsp1_uart3;
 	};
 
 	chosen {
-- 
2.23.0

Re: [PATCH] arm64: dts: qcom: msm8998-mtp: Add alias for blsp1_uart3

[Jeffrey Hugo]

On Fri, Nov 15, 2019 at 11:44 PM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> The msm_serial driver uses a simple counter to determine which port to
> use when no alias is defined, but there's no logic to prevent this from

Which port to use for what, the default console?

> not colliding with what's defined by the aliases. As a result either
> none or all of the active msm_serial instances must be listed as
> aliases.
>
> Define blsp1_uart3 as "serial1" to mitigate this problem.
>
> Fixes: 4cffb9f2c700 ("arm64: dts: qcom: msm8998-mtp: Enable bluetooth")
> Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

That driver behavior seems like a strange thing to be doing.

If you clarify the question above, -
Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>

> ---
>  arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> index 5f101a20a20a..e08fcb426bbf 100644
> --- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> +++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> @@ -9,6 +9,7 @@
>  / {
>         aliases {
>                 serial0 = &blsp2_uart1;
> +               serial1 = &blsp1_uart3;
>         };
>
>         chosen {
> --
> 2.23.0
>

Re: [PATCH] arm64: dts: qcom: msm8998-mtp: Add alias for blsp1_uart3

[Bjorn Andersson]

On Sat 16 Nov 14:24 PST 2019, Jeffrey Hugo wrote:

> On Fri, Nov 15, 2019 at 11:44 PM Bjorn Andersson
> <bjorn.andersson@linaro.org> wrote:
> >
> > The msm_serial driver uses a simple counter to determine which port to
> > use when no alias is defined, but there's no logic to prevent this from
> 
> Which port to use for what, the default console?
> 

The driver defines three (3) struct uart_ports (wrapped in struct
msm_ports), see msm_uart_port[] around line 1538 in msm_serial.c

This means that you can have a whooping 3 instances of msm_serial in the
system and per the logic found in msm_serial_probe() the allocation
follows the serial%d aliases defined and for entries without an alias a
simple counter, starting at 0 is used.

> > not colliding with what's defined by the aliases. As a result either
> > none or all of the active msm_serial instances must be listed as
> > aliases.
> >
> > Define blsp1_uart3 as "serial1" to mitigate this problem.
> >
> > Fixes: 4cffb9f2c700 ("arm64: dts: qcom: msm8998-mtp: Enable bluetooth")
> > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> 
> That driver behavior seems like a strange thing to be doing.
> 
> If you clarify the question above, -
> Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
> 

Thanks, I'll respin the message to properly document this behavior.

Regards,
Bjorn

> > ---
> >  arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 1 +
> >  1 file changed, 1 insertion(+)
> >
> > diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > index 5f101a20a20a..e08fcb426bbf 100644
> > --- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > +++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > @@ -9,6 +9,7 @@
> >  / {
> >         aliases {
> >                 serial0 = &blsp2_uart1;
> > +               serial1 = &blsp1_uart3;
> >         };
> >
> >         chosen {
> > --
> > 2.23.0
> >

Re: [PATCH] arm64: dts: qcom: msm8998-mtp: Add alias for blsp1_uart3

[Jeffrey Hugo]

On Sun, Nov 17, 2019 at 7:41 PM Bjorn Andersson
<bjorn.andersson@linaro.org> wrote:
>
> On Sat 16 Nov 14:24 PST 2019, Jeffrey Hugo wrote:
>
> > On Fri, Nov 15, 2019 at 11:44 PM Bjorn Andersson
> > <bjorn.andersson@linaro.org> wrote:
> > >
> > > The msm_serial driver uses a simple counter to determine which port to
> > > use when no alias is defined, but there's no logic to prevent this from
> >
> > Which port to use for what, the default console?
> >
>
> The driver defines three (3) struct uart_ports (wrapped in struct
> msm_ports), see msm_uart_port[] around line 1538 in msm_serial.c
>
> This means that you can have a whooping 3 instances of msm_serial in the
> system and per the logic found in msm_serial_probe() the allocation
> follows the serial%d aliases defined and for entries without an alias a
> simple counter, starting at 0 is used.

Ah.  Clearly no one needs more than 64k of memory, err 3 uart ports  :)

>
> > > not colliding with what's defined by the aliases. As a result either
> > > none or all of the active msm_serial instances must be listed as
> > > aliases.
> > >
> > > Define blsp1_uart3 as "serial1" to mitigate this problem.
> > >
> > > Fixes: 4cffb9f2c700 ("arm64: dts: qcom: msm8998-mtp: Enable bluetooth")
> > > Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
> >
> > That driver behavior seems like a strange thing to be doing.
> >
> > If you clarify the question above, -
> > Reviewed-by: Jeffrey Hugo <jeffrey.l.hugo@gmail.com>
> >
>
> Thanks, I'll respin the message to properly document this behavior.

Sounds good.

>
> Regards,
> Bjorn
>
> > > ---
> > >  arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi | 1 +
> > >  1 file changed, 1 insertion(+)
> > >
> > > diff --git a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > > index 5f101a20a20a..e08fcb426bbf 100644
> > > --- a/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > > +++ b/arch/arm64/boot/dts/qcom/msm8998-mtp.dtsi
> > > @@ -9,6 +9,7 @@
> > >  / {
> > >         aliases {
> > >                 serial0 = &blsp2_uart1;
> > > +               serial1 = &blsp1_uart3;
> > >         };
> > >
> > >         chosen {
> > > --
> > > 2.23.0
> > >