[cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[Biju Das]

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From: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>

commit 3dc4db3662366306e54ddcbda4804acb1258e4ba upstream.

For SCIF and HSCIF interfaces the SCxSR register holds the status of
data that is to be read next from SCxRDR register, But where as for
SCIFA and SCIFB interfaces SCxSR register holds status of data that is
previously read from SCxRDR register.

This patch makes sure the status register is read depending on the port
types so that errors are caught accordingly.

Cc: <stable@vger.kernel.org>
Signed-off-by: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
Signed-off-by: Hao Bui <hao.bui.yg@renesas.com>
Signed-off-by: KAZUMI HARADA <kazumi.harada.rh@renesas.com>
Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1585333048-31828-1-git-send-email-kazuhiro.fujita.jg@renesas.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
 drivers/tty/serial/sh-sci.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index 22f7201..2b5b342 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -793,9 +793,16 @@ static void sci_receive_chars(struct uart_port *port)
 				tty_insert_flip_char(tport, c, TTY_NORMAL);
 		} else {
 			for (i = 0; i < count; i++) {
-				char c = serial_port_in(port, SCxRDR);
-
-				status = serial_port_in(port, SCxSR);
+				char c;
+
+				if (port->type == PORT_SCIF ||
+				    port->type == PORT_HSCIF) {
+					status = serial_port_in(port, SCxSR);
+					c = serial_port_in(port, SCxRDR);
+				} else {
+					c = serial_port_in(port, SCxRDR);
+					status = serial_port_in(port, SCxSR);
+				}
 #if defined(CONFIG_CPU_SH3)
 				/* Skip "chars" during break */
 				if (sci_port->break_flag) {
-- 
2.7.4


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Re: [cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[Nobuhiro Iwamatsu]

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Hi,

> -----Original Message-----
> From: Biju Das [mailto:biju.das.jz@bp.renesas.com]
> Sent: Thursday, July 16, 2020 10:24 PM
> To: cip-dev@lists.cip-project.org; iwamatsu nobuhiro(岩松 信洋 □ＳＷＣ◯ＡＣＴ)
> <nobuhiro1.iwamatsu@toshiba.co.jp>; Pavel Machek <pavel@denx.de>
> Cc: Chris Paterson <chris.paterson2@renesas.com>; Biju Das <biju.das.jz@bp.renesas.com>; Prabhakar Mahadev Lad
> <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Subject: [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence
> 
> From: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> 
> commit 3dc4db3662366306e54ddcbda4804acb1258e4ba upstream.
> 
> For SCIF and HSCIF interfaces the SCxSR register holds the status of
> data that is to be read next from SCxRDR register, But where as for
> SCIFA and SCIFB interfaces SCxSR register holds status of data that is
> previously read from SCxRDR register.
> 
> This patch makes sure the status register is read depending on the port
> types so that errors are caught accordingly.
> 
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> Signed-off-by: Hao Bui <hao.bui.yg@renesas.com>
> Signed-off-by: KAZUMI HARADA <kazumi.harada.rh@renesas.com>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Link: https://lore.kernel.org/r/1585333048-31828-1-git-send-email-kazuhiro.fujita.jg@renesas.com
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>

Looks good to me.
I will merge if nothing else is mentioned.

Best regards,
  Nobuhiro

> ---
>  drivers/tty/serial/sh-sci.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> index 22f7201..2b5b342 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -793,9 +793,16 @@ static void sci_receive_chars(struct uart_port *port)
>  				tty_insert_flip_char(tport, c, TTY_NORMAL);
>  		} else {
>  			for (i = 0; i < count; i++) {
> -				char c = serial_port_in(port, SCxRDR);
> -
> -				status = serial_port_in(port, SCxSR);
> +				char c;
> +
> +				if (port->type == PORT_SCIF ||
> +				    port->type == PORT_HSCIF) {
> +					status = serial_port_in(port, SCxSR);
> +					c = serial_port_in(port, SCxRDR);
> +				} else {
> +					c = serial_port_in(port, SCxRDR);
> +					status = serial_port_in(port, SCxSR);
> +				}
>  #if defined(CONFIG_CPU_SH3)
>  				/* Skip "chars" during break */
>  				if (sci_port->break_flag) {
> --
> 2.7.4


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Re: [cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[Pavel Machek]

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Hi!

> > From: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> > 
> > commit 3dc4db3662366306e54ddcbda4804acb1258e4ba upstream.
> > 
> > For SCIF and HSCIF interfaces the SCxSR register holds the status of
> > data that is to be read next from SCxRDR register, But where as for
> > SCIFA and SCIFB interfaces SCxSR register holds status of data that is
> > previously read from SCxRDR register.
> > 
> > This patch makes sure the status register is read depending on the port
> > types so that errors are caught accordingly.
> > 
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> > Signed-off-by: Hao Bui <hao.bui.yg@renesas.com>
> > Signed-off-by: KAZUMI HARADA <kazumi.harada.rh@renesas.com>
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
> > Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > Link: https://lore.kernel.org/r/1585333048-31828-1-git-send-email-kazuhiro.fujita.jg@renesas.com
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> > Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> 
> Looks good to me.
> I will merge if nothing else is mentioned.

It looks good to me, and it passed basic testing -- so I applied the
patch and am pushing it. (I hope you don't mind).

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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Re: [cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[Pavel Machek]

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Hi!

> From: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> 
> commit 3dc4db3662366306e54ddcbda4804acb1258e4ba upstream.
> 
> For SCIF and HSCIF interfaces the SCxSR register holds the status of
> data that is to be read next from SCxRDR register, But where as for
> SCIFA and SCIFB interfaces SCxSR register holds status of data that is
> previously read from SCxRDR register.
> 
> This patch makes sure the status register is read depending on the port
> types so that errors are caught accordingly.

Looks good to me.

> Cc: <stable@vger.kernel.org>

I notice this applies cleanly to v4.4-stable. Was this submitted to
4.4 / do you need some help there?

Does this have user-visible impact?

Best regards,

								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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Re: [cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence

[Biju Das]

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Hi Pavel,

Thanks for the feedback.

> -----Original Message-----
> From: Pavel Machek <pavel@denx.de>
> Sent: 17 July 2020 09:25
> To: cip-dev@lists.cip-project.org
> Cc: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>; Pavel
> Machek <pavel@denx.de>; Chris Paterson <Chris.Paterson2@renesas.com>;
> Biju Das <biju.das.jz@bp.renesas.com>; Prabhakar Mahadev Lad
> <prabhakar.mahadev-lad.rj@bp.renesas.com>
> Subject: Re: [cip-dev] [PATCH 4.4.y-cip] serial: sh-sci: Make sure status
> register SCxSR is read in correct sequence
>
> Hi!
>
> > From: Kazuhiro Fujita <kazuhiro.fujita.jg@renesas.com>
> >
> > commit 3dc4db3662366306e54ddcbda4804acb1258e4ba upstream.
> >
> > For SCIF and HSCIF interfaces the SCxSR register holds the status of
> > data that is to be read next from SCxRDR register, But where as for
> > SCIFA and SCIFB interfaces SCxSR register holds status of data that is
> > previously read from SCxRDR register.
> >
> > This patch makes sure the status register is read depending on the
> > port types so that errors are caught accordingly.
>
> Looks good to me.
>
> > Cc: <stable@vger.kernel.org>
>
> I notice this applies cleanly to v4.4-stable. Was this submitted to
> 4.4 / do you need some help there?

The original patch is not cleanly applied on 4.4 see the mail below

https://www.spinics.net/lists/linux-renesas-soc/msg48219.html

> Does this have user-visible impact?

No, You can verify this on console after applying the patch.

stty evenp

Test Case 1:

paste "p" on the console should generate parity error and "o" should not

Test Case 2:-

paste "ppppp" on the console should generate parity error and "ooooo" should not

Testcase 3:-

Paste "pop", it should generate parity error for "p"

Regards,
Biju


Renesas Electronics Europe GmbH, Geschaeftsfuehrer/President: Carsten Jauch, Sitz der Gesellschaft/Registered office: Duesseldorf, Arcadiastrasse 10, 40472 Duesseldorf, Germany, Handelsregister/Commercial Register: Duesseldorf, HRB 3708 USt-IDNr./Tax identification no.: DE 119353406 WEEE-Reg.-Nr./WEEE reg. no.: DE 14978647

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