[PATCH ethtool v3 0/2] Adding downshift support to ethtool

[PATCH ethtool v3 0/2] Adding downshift support to ethtool

[Allan W. Nielsen]

Hi All,

(This is a re-post of the v3 patch set with a new cover letter - I was not
aware that the cover letters was used as commit comments in merge commits).

This patch implements for set/get downshifting.

Downshifting can either be turned on/off, or it can be configured to a
specifc count.

"count" is optional.

Tested on Beaglebone Black with VSC 8531 PHY.

Change set:
v1:
- Initial version of set/get phy tunable with downshift feature.
v2:
- (ethtool) Syntax is changed from "--set-phy-tunable downshift on|off|%d"
  to "--set-phy-tunable [downshift on|off [count N]]" - as requested by
  Andrew.
v3:
- Fixed Spelling in "ethtool-copy.h:sync with net" 
- Fixed "if send_ioctl() returns an error, print the error message and then
  still print th value of count".

Raju Lakkaraju (2):
  ethtool-copy.h:sync with net
  Ethtool: Implements ETHTOOL_PHY_GTUNABLE/ETHTOOL_PHY_STUNABLE and PHY
    downshift

 ethtool-copy.h |  18 +++++++-
 ethtool.8.in   |  39 ++++++++++++++++
 ethtool.c      | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 200 insertions(+), 1 deletion(-)

-- 
2.7.4

[PATCH ethtool v3 1/2] ethtool-copy.h:sync with net

[Allan W. Nielsen]

From: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>

This covers kernel changes upto:

commit f5a4732f85613b3fb43f8bc33a017e3db3b3605a
Author: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
Date:   Wed Nov 9 16:33:09 2016 +0530

    ethtool: (uapi) Add ETHTOOL_PHY_DOWNSHIFT to PHY tunables

    For operation in cabling environments that are incompatible with
    1000BASE-T, PHY device may provide an automatic link speed downshift
    operation. When enabled, the device automatically changes its 1000BASE-T
    auto-negotiation to the next slower speed after a configured number of
    failed attempts at 1000BASE-T.  This feature is useful in setting up in
    networks using older cable installations that include only pairs A and B,
    and not pairs C and D.

    Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
    Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
---
 ethtool-copy.h | 18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/ethtool-copy.h b/ethtool-copy.h
index 70748f5..2e2448f 100644
--- a/ethtool-copy.h
+++ b/ethtool-copy.h
@@ -247,6 +247,19 @@ struct ethtool_tunable {
 	void	*data[0];
 };
 
+#define DOWNSHIFT_DEV_DEFAULT_COUNT	0xff
+#define DOWNSHIFT_DEV_DISABLE		0
+
+enum phy_tunable_id {
+	ETHTOOL_PHY_ID_UNSPEC,
+	ETHTOOL_PHY_DOWNSHIFT,
+	/*
+	 * Add your fresh new phy tunable attribute above and remember to update
+	 * phy_tunable_strings[] in net/core/ethtool.c
+	 */
+	__ETHTOOL_PHY_TUNABLE_COUNT,
+};
+
 /**
  * struct ethtool_regs - hardware register dump
  * @cmd: Command number = %ETHTOOL_GREGS
@@ -547,6 +560,7 @@ struct ethtool_pauseparam {
  * @ETH_SS_FEATURES: Device feature names
  * @ETH_SS_RSS_HASH_FUNCS: RSS hush function names
  * @ETH_SS_PHY_STATS: Statistic names, for use with %ETHTOOL_GPHYSTATS
+ * @ETH_SS_PHY_TUNABLES: PHY tunable names
  */
 enum ethtool_stringset {
 	ETH_SS_TEST		= 0,
@@ -557,6 +571,7 @@ enum ethtool_stringset {
 	ETH_SS_RSS_HASH_FUNCS,
 	ETH_SS_TUNABLES,
 	ETH_SS_PHY_STATS,
+	ETH_SS_PHY_TUNABLES,
 };
 
 /**
@@ -1312,7 +1327,8 @@ struct ethtool_per_queue_op {
 
 #define ETHTOOL_GLINKSETTINGS	0x0000004c /* Get ethtool_link_settings */
 #define ETHTOOL_SLINKSETTINGS	0x0000004d /* Set ethtool_link_settings */
-
+#define ETHTOOL_PHY_GTUNABLE	0x0000004e /* Get PHY tunable configuration */
+#define ETHTOOL_PHY_STUNABLE	0x0000004f /* Set PHY tunable configuration */
 
 /* compatibility with older code */
 #define SPARC_ETH_GSET		ETHTOOL_GSET
-- 
2.7.3

Re: [PATCH ethtool v3 1/2] ethtool-copy.h:sync with net

[Florian Fainelli]

On 11/17/2016 04:07 AM, Allan W. Nielsen wrote:
> From: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
> 
> This covers kernel changes upto:
> 
> commit f5a4732f85613b3fb43f8bc33a017e3db3b3605a
> Author: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
> Date:   Wed Nov 9 16:33:09 2016 +0530
> 
>     ethtool: (uapi) Add ETHTOOL_PHY_DOWNSHIFT to PHY tunables
> 
>     For operation in cabling environments that are incompatible with
>     1000BASE-T, PHY device may provide an automatic link speed downshift
>     operation. When enabled, the device automatically changes its 1000BASE-T
>     auto-negotiation to the next slower speed after a configured number of
>     failed attempts at 1000BASE-T.  This feature is useful in setting up in
>     networks using older cable installations that include only pairs A and B,
>     and not pairs C and D.
> 
>     Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
>     Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
-- 
Florian

[PATCH ethtool v3 2/2] Ethtool: Implements ETHTOOL_PHY_GTUNABLE/ETHTOOL_PHY_STUNABLE and PHY downshift

[Allan W. Nielsen]

From: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>

Add ethtool get and set tunable to access PHY drivers.

Ethtool Help: ethtool -h for PHY tunables
    ethtool --set-phy-tunable DEVNAME      Set PHY tunable
                [ downshift on|off [count N] ]
    ethtool --get-phy-tunable DEVNAME      Get PHY tunable
                [ downshift ]

Ethtool ex:
  ethtool --set-phy-tuanble eth0 downshift on
  ethtool --set-phy-tuanble eth0 downshift off
  ethtool --set-phy-tuanble eth0 downshift on count 2

  ethtool --get-phy-tunable eth0 downshift

Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
---
 ethtool.8.in |  39 ++++++++++++++++
 ethtool.c    | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 183 insertions(+)

diff --git a/ethtool.8.in b/ethtool.8.in
index 9631847..337d0cf 100644
--- a/ethtool.8.in
+++ b/ethtool.8.in
@@ -340,6 +340,18 @@ ethtool \- query or control network driver and hardware settings
 .B2 tx-lpi on off
 .BN tx-timer
 .BN advertise
+.HP
+.B ethtool \-\-set\-phy\-tunable
+.I devname
+.RB [
+.B downshift
+.A1 on off
+.BN count
+.RB ]
+.HP
+.B ethtool \-\-get\-phy\-tunable
+.I devname
+.RB [ downshift ]
 .
 .\" Adjust lines (i.e. full justification) and hyphenate.
 .ad
@@ -947,6 +959,33 @@ Values are as for
 Sets the amount of time the device should stay in idle mode prior to asserting
 its Tx LPI (in microseconds). This has meaning only when Tx LPI is enabled.
 .RE
+.TP
+.B \-\-set\-phy\-tunable
+Sets the PHY tunable parameters.
+.RS 4
+.TP
+.A2 downshift on off
+Specifies whether downshift should be enabled
+.TS
+nokeep;
+lB	l.
+.BI count \ N
+Sets the PHY downshift re-tries count.
+.TE
+.PD
+.RE
+.TP
+.B \-\-get\-phy\-tunable
+Gets the PHY tunable parameters.
+.RS 4
+.TP
+.B downshift
+For operation in cabling environments that are incompatible with 1000BASE-T,
+PHY device provides an automatic link speed downshift operation.
+Link speed downshift after N failed 1000BASE-T auto-negotiation attempts.
+
+Gets the PHY downshift count/status.
+.RE
 .SH BUGS
 Not supported (in part or whole) on all network drivers.
 .SH AUTHOR
diff --git a/ethtool.c b/ethtool.c
index 49ac94e..7dcd005 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -4520,6 +4520,146 @@ static int do_seee(struct cmd_context *ctx)
 	return 0;
 }
 
+static int do_get_phy_tunable(struct cmd_context *ctx)
+{
+	int argc = ctx->argc;
+	char **argp = ctx->argp;
+	int err, i;
+	u8 downshift_changed = 0;
+
+	if (argc < 1)
+		exit_bad_args();
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argp[i], "downshift")) {
+			downshift_changed = 1;
+			i += 1;
+			if (i < argc)
+				exit_bad_args();
+		} else  {
+			exit_bad_args();
+		}
+	}
+
+	if (downshift_changed) {
+		struct ethtool_tunable ds;
+		u8 count = 0;
+
+		ds.cmd = ETHTOOL_PHY_GTUNABLE;
+		ds.id = ETHTOOL_PHY_DOWNSHIFT;
+		ds.type_id = ETHTOOL_TUNABLE_U8;
+		ds.len = 1;
+		ds.data[0] = &count;
+		err = send_ioctl(ctx, &ds);
+		if (err < 0) {
+			perror("Cannot Get PHY downshift count");
+			return 87;
+		}
+		count = *((u8 *)&ds.data[0]);
+		if (count)
+			fprintf(stdout, "Downshift count: %d\n", count);
+		else
+			fprintf(stdout, "Downshift disabled\n");
+	}
+
+	return err;
+}
+
+static int parse_named_bool(struct cmd_context *ctx, const char *name, u8 *on)
+{
+	if (ctx->argc < 2)
+		return 0;
+
+	if (strcmp(*ctx->argp, name))
+		return 0;
+
+	if (!strcmp(*(ctx->argp + 1), "on")) {
+		*on = 1;
+	} else if (!strcmp(*(ctx->argp + 1), "off")) {
+		*on = 0;
+	} else {
+		fprintf(stderr, "Invalid boolean\n");
+		exit_bad_args();
+	}
+
+	ctx->argc -= 2;
+	ctx->argp += 2;
+
+	return 1;
+}
+
+static int parse_named_u8(struct cmd_context *ctx, const char *name, u8 *val)
+{
+	if (ctx->argc < 2)
+		return 0;
+
+	if (strcmp(*ctx->argp, name))
+		return 0;
+
+	*val = get_uint_range(*(ctx->argp + 1), 0, 0xff);
+
+	ctx->argc -= 2;
+	ctx->argp += 2;
+
+	return 1;
+}
+
+static int do_set_phy_tunable(struct cmd_context *ctx)
+{
+	int err = 0;
+	u8 ds_cnt = DOWNSHIFT_DEV_DEFAULT_COUNT;
+	u8 ds_changed = 0, ds_has_cnt = 0, ds_enable = 0;
+
+	if (ctx->argc == 0)
+		exit_bad_args();
+
+	/* Parse arguments */
+	while (ctx->argc) {
+		if (parse_named_bool(ctx, "downshift", &ds_enable)) {
+			ds_changed = 1;
+			ds_has_cnt = parse_named_u8(ctx, "count", &ds_cnt);
+		} else {
+			exit_bad_args();
+		}
+	}
+
+	/* Validate parameters */
+	if (ds_changed) {
+		if (!ds_enable && ds_has_cnt) {
+			fprintf(stderr, "'count' may not be set when downshift "
+				        "is off.\n");
+			exit_bad_args();
+		}
+
+		if (ds_enable && ds_has_cnt && ds_cnt == 0) {
+			fprintf(stderr, "'count' may not be zero.\n");
+			exit_bad_args();
+		}
+
+		if (!ds_enable)
+			ds_cnt = DOWNSHIFT_DEV_DISABLE;
+	}
+
+	/* Do it */
+	if (ds_changed) {
+		struct ethtool_tunable ds;
+		u8 count;
+
+		ds.cmd = ETHTOOL_PHY_STUNABLE;
+		ds.id = ETHTOOL_PHY_DOWNSHIFT;
+		ds.type_id = ETHTOOL_TUNABLE_U8;
+		ds.len = 1;
+		ds.data[0] = &count;
+		*((u8 *)&ds.data[0]) = ds_cnt;
+		err = send_ioctl(ctx, &ds);
+		if (err < 0) {
+			perror("Cannot Set PHY downshift count");
+			err = 87;
+		}
+	}
+
+	return err;
+}
+
 #ifndef TEST_ETHTOOL
 int send_ioctl(struct cmd_context *ctx, void *cmd)
 {
@@ -4681,6 +4821,10 @@ static const struct option {
 	  "		[ advertise %x ]\n"
 	  "		[ tx-lpi on|off ]\n"
 	  "		[ tx-timer %d ]\n"},
+	{ "--set-phy-tunable", 1, do_set_phy_tunable, "Set PHY tunable",
+	  "		[ downshift on|off [count N] ]\n"},
+	{ "--get-phy-tunable", 1, do_get_phy_tunable, "Get PHY tunable",
+	  "		[ downshift ]\n"},
 	{ "-h|--help", 0, show_usage, "Show this help" },
 	{ "--version", 0, do_version, "Show version number" },
 	{}
-- 
2.7.3

Re: [PATCH ethtool v3 2/2] Ethtool: Implements ETHTOOL_PHY_GTUNABLE/ETHTOOL_PHY_STUNABLE and PHY downshift

[Florian Fainelli]

On 11/17/2016 04:08 AM, Allan W. Nielsen wrote:
> From: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
> 
> Add ethtool get and set tunable to access PHY drivers.
> 
> Ethtool Help: ethtool -h for PHY tunables
>     ethtool --set-phy-tunable DEVNAME      Set PHY tunable
>                 [ downshift on|off [count N] ]
>     ethtool --get-phy-tunable DEVNAME      Get PHY tunable
>                 [ downshift ]
> 
> Ethtool ex:
>   ethtool --set-phy-tuanble eth0 downshift on
>   ethtool --set-phy-tuanble eth0 downshift off
>   ethtool --set-phy-tuanble eth0 downshift on count 2


s/tunable/tunable/

Since this will be used as examples for people testing this feature,
this is kind of important to get the example right ;)

Other than that:

Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>

> 
>   ethtool --get-phy-tunable eth0 downshift
> 
> Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
> Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
> ---

> +.B downshift
> +For operation in cabling environments that are incompatible with 1000BASE-T,
> +PHY device provides an automatic link speed downshift operation.

Might be worth mentioning that this is particularly useful if you are
using a cable which does not have the 4 pairs for instance.
-- 
Florian

[PATCH ethtool v3 0/2] Adding downshift support to ethtool

[Allan W. Nielsen]

Hi All,

This is a follow-up on the v2 patch series.

Following is updated:

- Spelling
- consistent spaces
- error handling of send_ioctl()

Old cover letters included below.

Please review.

Best regards
Allan and Raju


Raju Lakkaraju (2):
  ethtool-copy.h:sync with net
  Ethtool: Implements ETHTOOL_PHY_GTUNABLE/ETHTOOL_PHY_STUNABLE and PHY
    downshift

 ethtool-copy.h |  18 +++++++-
 ethtool.8.in   |  39 ++++++++++++++++
 ethtool.c      | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 200 insertions(+), 1 deletion(-)

> From c235004654ee0212b6cf6ca7af14eb6ef8a04dee Mon Sep 17 00:00:00 2001
> From: "Allan W. Nielsen" <allan.nielsen@microsemi.com>
> Date: Mon, 14 Nov 2016 10:22:03 +0100
> Subject: [PATCH ethtool v2 0/2] Adding downshift support to ethtool
> 
> This is a follow-up on the patch series posted at Fri, 4 Nov 2016 11:27:31 +0100
> (old cover letter included below).
> 
> The following is changed/added/addressed:
> - Syntax is changed from "--set-phy-tunable downshift on|off|%d" to
>   "--set-phy-tunable [downshift on|off [count N]]" - as requested by Andrew.
> - Short description of downshifting is added to the man page.
>
> Old cover letter:
> > From 5d926ca56f13e283aaa98e820d4720305be4da8f Mon Sep 17 00:00:00 2001
> > From: "Allan W. Nielsen" <allan.nielsen@microsemi.com>
> > Date: Fri, 4 Nov 2016 11:27:31 +0100
> > Subject: [PATCH ethtool 0/2] Adding downshift support to ethtool
> > 
> > Hi All,
> > 
> > This patch implements for set/get downshifting.
> > 
> > Downshifting can either be turned on/off, or it can be configured to a
> > specifc count.
> > 
> > If no "count" are provided, then it is up to the individual PHY driver to
> > configure a default count.

-- 
2.7.3

[PATCH ethtool v3 2/2] Ethtool: Implements ETHTOOL_PHY_GTUNABLE/ETHTOOL_PHY_STUNABLE and PHY downshift

[Allan W. Nielsen]

From: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>

Add ethtool get and set tunable to access PHY drivers.

Ethtool Help: ethtool -h for PHY tunables
    ethtool --set-phy-tunable DEVNAME      Set PHY tunable
                [ downshift on|off [count N] ]
    ethtool --get-phy-tunable DEVNAME      Get PHY tunable
                [ downshift ]

Ethtool ex:
  ethtool --set-phy-tuanble eth0 downshift on
  ethtool --set-phy-tuanble eth0 downshift off
  ethtool --set-phy-tuanble eth0 downshift on count 2

  ethtool --get-phy-tunable eth0 downshift

Signed-off-by: Raju Lakkaraju <Raju.Lakkaraju@microsemi.com>
Signed-off-by: Allan W. Nielsen <allan.nielsen@microsemi.com>
---
 ethtool.8.in |  39 ++++++++++++++++
 ethtool.c    | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 183 insertions(+)

diff --git a/ethtool.8.in b/ethtool.8.in
index 9631847..337d0cf 100644
--- a/ethtool.8.in
+++ b/ethtool.8.in
@@ -340,6 +340,18 @@ ethtool \- query or control network driver and hardware settings
 .B2 tx-lpi on off
 .BN tx-timer
 .BN advertise
+.HP
+.B ethtool \-\-set\-phy\-tunable
+.I devname
+.RB [
+.B downshift
+.A1 on off
+.BN count
+.RB ]
+.HP
+.B ethtool \-\-get\-phy\-tunable
+.I devname
+.RB [ downshift ]
 .
 .\" Adjust lines (i.e. full justification) and hyphenate.
 .ad
@@ -947,6 +959,33 @@ Values are as for
 Sets the amount of time the device should stay in idle mode prior to asserting
 its Tx LPI (in microseconds). This has meaning only when Tx LPI is enabled.
 .RE
+.TP
+.B \-\-set\-phy\-tunable
+Sets the PHY tunable parameters.
+.RS 4
+.TP
+.A2 downshift on off
+Specifies whether downshift should be enabled
+.TS
+nokeep;
+lB	l.
+.BI count \ N
+Sets the PHY downshift re-tries count.
+.TE
+.PD
+.RE
+.TP
+.B \-\-get\-phy\-tunable
+Gets the PHY tunable parameters.
+.RS 4
+.TP
+.B downshift
+For operation in cabling environments that are incompatible with 1000BASE-T,
+PHY device provides an automatic link speed downshift operation.
+Link speed downshift after N failed 1000BASE-T auto-negotiation attempts.
+
+Gets the PHY downshift count/status.
+.RE
 .SH BUGS
 Not supported (in part or whole) on all network drivers.
 .SH AUTHOR
diff --git a/ethtool.c b/ethtool.c
index 49ac94e..7dcd005 100644
--- a/ethtool.c
+++ b/ethtool.c
@@ -4520,6 +4520,146 @@ static int do_seee(struct cmd_context *ctx)
 	return 0;
 }
 
+static int do_get_phy_tunable(struct cmd_context *ctx)
+{
+	int argc = ctx->argc;
+	char **argp = ctx->argp;
+	int err, i;
+	u8 downshift_changed = 0;
+
+	if (argc < 1)
+		exit_bad_args();
+	for (i = 0; i < argc; i++) {
+		if (!strcmp(argp[i], "downshift")) {
+			downshift_changed = 1;
+			i += 1;
+			if (i < argc)
+				exit_bad_args();
+		} else  {
+			exit_bad_args();
+		}
+	}
+
+	if (downshift_changed) {
+		struct ethtool_tunable ds;
+		u8 count = 0;
+
+		ds.cmd = ETHTOOL_PHY_GTUNABLE;
+		ds.id = ETHTOOL_PHY_DOWNSHIFT;
+		ds.type_id = ETHTOOL_TUNABLE_U8;
+		ds.len = 1;
+		ds.data[0] = &count;
+		err = send_ioctl(ctx, &ds);
+		if (err < 0) {
+			perror("Cannot Get PHY downshift count");
+			return 87;
+		}
+		count = *((u8 *)&ds.data[0]);
+		if (count)
+			fprintf(stdout, "Downshift count: %d\n", count);
+		else
+			fprintf(stdout, "Downshift disabled\n");
+	}
+
+	return err;
+}
+
+static int parse_named_bool(struct cmd_context *ctx, const char *name, u8 *on)
+{
+	if (ctx->argc < 2)
+		return 0;
+
+	if (strcmp(*ctx->argp, name))
+		return 0;
+
+	if (!strcmp(*(ctx->argp + 1), "on")) {
+		*on = 1;
+	} else if (!strcmp(*(ctx->argp + 1), "off")) {
+		*on = 0;
+	} else {
+		fprintf(stderr, "Invalid boolean\n");
+		exit_bad_args();
+	}
+
+	ctx->argc -= 2;
+	ctx->argp += 2;
+
+	return 1;
+}
+
+static int parse_named_u8(struct cmd_context *ctx, const char *name, u8 *val)
+{
+	if (ctx->argc < 2)
+		return 0;
+
+	if (strcmp(*ctx->argp, name))
+		return 0;
+
+	*val = get_uint_range(*(ctx->argp + 1), 0, 0xff);
+
+	ctx->argc -= 2;
+	ctx->argp += 2;
+
+	return 1;
+}
+
+static int do_set_phy_tunable(struct cmd_context *ctx)
+{
+	int err = 0;
+	u8 ds_cnt = DOWNSHIFT_DEV_DEFAULT_COUNT;
+	u8 ds_changed = 0, ds_has_cnt = 0, ds_enable = 0;
+
+	if (ctx->argc == 0)
+		exit_bad_args();
+
+	/* Parse arguments */
+	while (ctx->argc) {
+		if (parse_named_bool(ctx, "downshift", &ds_enable)) {
+			ds_changed = 1;
+			ds_has_cnt = parse_named_u8(ctx, "count", &ds_cnt);
+		} else {
+			exit_bad_args();
+		}
+	}
+
+	/* Validate parameters */
+	if (ds_changed) {
+		if (!ds_enable && ds_has_cnt) {
+			fprintf(stderr, "'count' may not be set when downshift "
+				        "is off.\n");
+			exit_bad_args();
+		}
+
+		if (ds_enable && ds_has_cnt && ds_cnt == 0) {
+			fprintf(stderr, "'count' may not be zero.\n");
+			exit_bad_args();
+		}
+
+		if (!ds_enable)
+			ds_cnt = DOWNSHIFT_DEV_DISABLE;
+	}
+
+	/* Do it */
+	if (ds_changed) {
+		struct ethtool_tunable ds;
+		u8 count;
+
+		ds.cmd = ETHTOOL_PHY_STUNABLE;
+		ds.id = ETHTOOL_PHY_DOWNSHIFT;
+		ds.type_id = ETHTOOL_TUNABLE_U8;
+		ds.len = 1;
+		ds.data[0] = &count;
+		*((u8 *)&ds.data[0]) = ds_cnt;
+		err = send_ioctl(ctx, &ds);
+		if (err < 0) {
+			perror("Cannot Set PHY downshift count");
+			err = 87;
+		}
+	}
+
+	return err;
+}
+
 #ifndef TEST_ETHTOOL
 int send_ioctl(struct cmd_context *ctx, void *cmd)
 {
@@ -4681,6 +4821,10 @@ static const struct option {
 	  "		[ advertise %x ]\n"
 	  "		[ tx-lpi on|off ]\n"
 	  "		[ tx-timer %d ]\n"},
+	{ "--set-phy-tunable", 1, do_set_phy_tunable, "Set PHY tunable",
+	  "		[ downshift on|off [count N] ]\n"},
+	{ "--get-phy-tunable", 1, do_get_phy_tunable, "Get PHY tunable",
+	  "		[ downshift ]\n"},
 	{ "-h|--help", 0, show_usage, "Show this help" },
 	{ "--version", 0, do_version, "Show version number" },
 	{}
-- 
2.7.3