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

Message ID 1594905847-54471-1-git-send-email-biju.das.jz@bp.renesas.com
State Accepted
Delegated to: Pavel Machek
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  • [4.4.y-cip] serial: sh-sci: Make sure status register SCxSR is read in correct sequence
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Commit Message

Biju Das July 16, 2020, 1:24 p.m. UTC
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(-)

Comments

Nobuhiro Iwamatsu July 17, 2020, 6:34 a.m. UTC | #1
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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Pavel Machek July 17, 2020, 8:24 a.m. UTC | #2
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
Biju Das July 17, 2020, 9 a.m. UTC | #3
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


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Pavel Machek July 17, 2020, 9:02 p.m. UTC | #4
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

Patch
diff mbox series

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) {