[net-next] cxgb4: don't hold RTNL during ethtool phys_id

The Chelsio cxgb4 drivers implement blinking in a unique way by
waiting on the mailbox. This patch cleans it up slightly by no longer
holding the system wide network configuration lock during the process.

The patch also uses correct semantics for the time argument
which is supposed to be in seconds; and zero is supposed
to signify infinite blinking.

This is still a bad firmware interface design for this
since it means the board is basically hung while doing the blink.
But fixing it correctly would require hardware and firmware
documentation. With that information the device could be converted
to the new set_phys_id.

Compile tested only.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

---
 drivers/net/cxgb4/cxgb4_main.c     |   17 ++++++++++++++---
 drivers/net/cxgb4vf/cxgb4vf_main.c |   21 +++++++++++++++++++--
 2 files changed, 33 insertions(+), 5 deletions(-)

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| From: Stephen Hemminger <shemminger@linux-foundation.org>
| Date: Wednesday, April 06, 2011 05:09 pm
| 
| The Chelsio cxgb4 drivers implement blinking in a unique way by
| waiting on the mailbox. This patch cleans it up slightly by no longer
| holding the system wide network configuration lock during the process.
| 
| The patch also uses correct semantics for the time argument
| which is supposed to be in seconds; and zero is supposed
| to signify infinite blinking.
| 
| This is still a bad firmware interface design for this
| since it means the board is basically hung while doing the blink.
| But fixing it correctly would require hardware and firmware
| documentation. With that information the device could be converted
| to the new set_phys_id.
| 
| Compile tested only.
| 
| Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>

  Are you assuming that the firmware won't respond with a command completion 
until the LED blinking is complete?  If so, that's a bad assumption.  The 
firmware runs as an asynchronous real-time OS.  The LED blinking simply becomes 
a thread of activity within the OS and the command completes immediately.

Casey

| ---
|  drivers/net/cxgb4/cxgb4_main.c     |   17 ++++++++++++++---
|  drivers/net/cxgb4vf/cxgb4vf_main.c |   21 +++++++++++++++++++--
|  2 files changed, 33 insertions(+), 5 deletions(-)
| 
| --- a/drivers/net/cxgb4/cxgb4_main.c	2011-04-06 16:49:02.045648800 -0700
| +++ b/drivers/net/cxgb4/cxgb4_main.c	2011-04-06 17:00:59.508851692 -0700
| @@ -1339,12 +1339,23 @@ static int restart_autoneg(struct net_de
|  static int identify_port(struct net_device *dev, u32 data)
|  {
|  	struct adapter *adap = netdev2adap(dev);
| +	int rc;
| +	unsigned long blinks;
| 
|  	if (data == 0)
| -		data = 2;     /* default to 2 seconds */
| +		blinks = UINT_MAX;
| +	else
| +		blinks = 2*data + data/2;
| 
| -	return t4_identify_port(adap, adap->fn, netdev2pinfo(dev)->viid,
| -				data * 5);
| +	/* Don't block networking updates while blink is in progress */
| +	dev_hold(dev);
| +	rtnl_unlock();
| +
| +	rc = t4_identify_port(adap, adap->fn, netdev2pinfo(dev)->viid,
| +			      blinks);
| +	rtnl_lock();
| +	dev_put(dev);
| +	return rc;
|  }
| 
|  static unsigned int from_fw_linkcaps(unsigned int type, unsigned int caps)
| --- a/drivers/net/cxgb4vf/cxgb4vf_main.c	2011-04-06 16:49:09.989728600
| -0700 +++ b/drivers/net/cxgb4vf/cxgb4vf_main.c	2011-04-06
| 17:02:38.609846223 -0700 @@ -43,6 +43,7 @@
|  #include <linux/etherdevice.h>
|  #include <linux/debugfs.h>
|  #include <linux/ethtool.h>
| +#include <linux/rtnetlink.h>
| 
|  #include "t4vf_common.h"
|  #include "t4vf_defs.h"
| @@ -1352,11 +1353,27 @@ static int cxgb4vf_set_rx_csum(struct ne
|  /*
|   * Identify the port by blinking the port's LED.
|   */
| -static int cxgb4vf_phys_id(struct net_device *dev, u32 id)
| +static int cxgb4vf_phys_id(struct net_device *dev, u32 data)
|  {
|  	struct port_info *pi = netdev_priv(dev);
| +	int rc;
| +	unsigned int blinks;
| 
| -	return t4vf_identify_port(pi->adapter, pi->viid, 5);
| +	if (data == 0)
| +		blinks = UINT_MAX;
| +	else
| +		blinks = 2*data + data/2;
| +
| +	/* Don't block networking updates while blink is in progress */
| +	dev_hold(dev);
| +	rtnl_unlock();
| +
| +	rc =  t4vf_identify_port(pi->adapter, pi->viid, blinks);
| +
| +	rtnl_lock();
| +	dev_put(dev);
| +
| +	return rc;
|  }
| 
|  /*
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On Wed, 6 Apr 2011 17:20:29 -0700
Casey Leedom <leedom@chelsio.com> wrote:

> | From: Stephen Hemminger <shemminger@linux-foundation.org>
> | Date: Wednesday, April 06, 2011 05:09 pm
> | 
> | The Chelsio cxgb4 drivers implement blinking in a unique way by
> | waiting on the mailbox. This patch cleans it up slightly by no longer
> | holding the system wide network configuration lock during the process.
> | 
> | The patch also uses correct semantics for the time argument
> | which is supposed to be in seconds; and zero is supposed
> | to signify infinite blinking.
> | 
> | This is still a bad firmware interface design for this
> | since it means the board is basically hung while doing the blink.
> | But fixing it correctly would require hardware and firmware
> | documentation. With that information the device could be converted
> | to the new set_phys_id.
> | 
> | Compile tested only.
> | 
> | Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
> 
>   Are you assuming that the firmware won't respond with a command completion 
> until the LED blinking is complete?  If so, that's a bad assumption.  The 
> firmware runs as an asynchronous real-time OS.  The LED blinking simply becomes 
> a thread of activity within the OS and the command completes immediately.
> 
> Casey

Then how is LED blinking stopped?
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On Wed, 2011-04-06 at 17:20 -0700, Casey Leedom wrote:
> | From: Stephen Hemminger <shemminger@linux-foundation.org>
> | Date: Wednesday, April 06, 2011 05:09 pm
> | 
> | The Chelsio cxgb4 drivers implement blinking in a unique way by
> | waiting on the mailbox. This patch cleans it up slightly by no longer
> | holding the system wide network configuration lock during the process.
> | 
> | The patch also uses correct semantics for the time argument
> | which is supposed to be in seconds; and zero is supposed
> | to signify infinite blinking.
> | 
> | This is still a bad firmware interface design for this
> | since it means the board is basically hung while doing the blink.
> | But fixing it correctly would require hardware and firmware
> | documentation. With that information the device could be converted
> | to the new set_phys_id.
> | 
> | Compile tested only.
> | 
> | Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
> 
>   Are you assuming that the firmware won't respond with a command completion 
> until the LED blinking is complete?  If so, that's a bad assumption.  The 
> firmware runs as an asynchronous real-time OS.  The LED blinking simply becomes 
> a thread of activity within the OS and the command completes immediately.
[...]

Stephen was assuming (as I did) that you actually implemented this
operation correctly.  You're supposed to blink the LED for the specified
time but let the user interrupt early.  If you just start the LED
blinking and then return, then it appears the user has no way to
interrupt it.

Is there a defined firmware command to stop blinking the LED?

Ben.

Stephen Hemminger wrote:
> On Wed, 6 Apr 2011 17:20:29 -0700
> Casey Leedom <leedom@chelsio.com> wrote:
> 
>> | From: Stephen Hemminger <shemminger@linux-foundation.org>
>> | Date: Wednesday, April 06, 2011 05:09 pm
>> | 
>> | The Chelsio cxgb4 drivers implement blinking in a unique way by
>> | waiting on the mailbox. This patch cleans it up slightly by no longer
>> | holding the system wide network configuration lock during the process.
>> | 
>> | The patch also uses correct semantics for the time argument
>> | which is supposed to be in seconds; and zero is supposed
>> | to signify infinite blinking.
>> | 
>> | This is still a bad firmware interface design for this
>> | since it means the board is basically hung while doing the blink.
>> | But fixing it correctly would require hardware and firmware
>> | documentation. With that information the device could be converted
>> | to the new set_phys_id.
>> | 
>> | Compile tested only.
>> | 
>> | Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
>>
>>   Are you assuming that the firmware won't respond with a command completion 
>> until the LED blinking is complete?  If so, that's a bad assumption.  The 
>> firmware runs as an asynchronous real-time OS.  The LED blinking simply becomes 
>> a thread of activity within the OS and the command completes immediately.
>>
>> Casey
> 
> Then how is LED blinking stopped?

You can pass 0 as blinks to cancel your request, which may or may not cancel 
the LED blinking depending on what other drivers have concurrent blinking 
requests in progress.  But you can't pass UINT_MAX as the patch does.  I'll 
fix it up to use the new ethtool interface this week.
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