[PATCH net-next] ieee802154: use helper function to get rid of redundancy

[PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Jean Sacren]

In some call sites of at86rf230_write_subreg(), they are rather
redundant. Use a helper function to replace those call sites for
efficiency.

With at86rf230_write_subreg_by_page(), now ->rssi_base_val is
assigned before at86rf230_write_subreg() is evaluated. Looking at
at86rf230_write_subreg(), that change could possibly affect

		__at86rf230_read_subreg()
and
		__at86rf230_write()

only or vice versa. Yet by the definition of

		struct at86rf230_local

changing ->rssi_base_val will in no way affect those two functions
above and evaluation of those two has no impact on ->rssi_base_val.
Thus, at86rf230_write_subreg_by_page() itself is safe.

Additionally at86rf230_write_subreg_by_channel() is simple and safe.

Signed-off-by: Jean Sacren <sakiwit@gmail.com>
---
 drivers/net/ieee802154/at86rf230.c | 34 +++++++++++++++++++++++-----------
 1 file changed, 23 insertions(+), 11 deletions(-)

diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
index 4517b149ed07..5aecbd1c402c 100644
--- a/drivers/net/ieee802154/at86rf230.c
+++ b/drivers/net/ieee802154/at86rf230.c
@@ -597,25 +597,37 @@ at86rf230_set_channel(struct at86rf230_local *lp, int page, int channel)
 	return at86rf230_write_subreg(lp, SR_CHANNEL, channel);
 }
 
+static int at86rf230_write_subreg_by_channel(struct at86rf230_local *lp,
+					     int channel)
+{
+	if (channel)
+		channel = 1;
+
+	return at86rf230_write_subreg(lp, SR_SUB_MODE, channel);
+}
+
+static int at86rf230_write_subreg_by_page(struct at86rf230_local *lp, int page)
+{
+	if (page) {
+		lp->rssi_base_val = -98;
+		page = 1;
+	} else {
+		lp->rssi_base_val = -100;
+	}
+
+	return at86rf230_write_subreg(lp, SR_BPSK_QPSK, page);
+}
+
 static int
 at86rf212_set_channel(struct at86rf230_local *lp, int page, int channel)
 {
 	int rc;
 
-	if (channel == 0)
-		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 0);
-	else
-		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 1);
+	rc = at86rf230_write_subreg_by_channel(lp, channel);
 	if (rc < 0)
 		return rc;
 
-	if (page == 0) {
-		rc = at86rf230_write_subreg(lp, SR_BPSK_QPSK, 0);
-		lp->rssi_base_val = -100;
-	} else {
-		rc = at86rf230_write_subreg(lp, SR_BPSK_QPSK, 1);
-		lp->rssi_base_val = -98;
-	}
+	rc = at86rf230_write_subreg_by_page(lp, page);
 	if (rc < 0)
 		return rc;
 

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Alexander Aring]

Hi Jean,

the at86rf230 driver supports several at86rf2xx chips. You split the
at86rf212_set_channel which is at86rf212 specific in two function which
are named at86rf230_foo.

Sorry, but I think we should not do this. One reason is that the code is
much easier to read when we have one channel_set callback for at86rf23x
and at86rf212 chips.



Btw. I preparing a big cleanup for this driver which supports regmap and
asychronous handling for rx/tx paths.

- Alex

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Jean Sacren]

From: Alexander Aring <alex.aring@gmail.com>
Date: Sun, 01 Jun 2014 09:26:57 +0200

Hi Alex,

Thank you very much for the feedback.

> the at86rf230 driver supports several at86rf2xx chips. You split the
> at86rf212_set_channel which is at86rf212 specific in two function which
> are named at86rf230_foo.

I didn't "split" at86rf212_set_channel() in two functions. I spliced
those two sections of code and made at86rf212_set_channel() far
succinct and easy to read.

> Sorry, but I think we should not do this. One reason is that the code is
> much easier to read when we have one channel_set callback for at86rf23x
> and at86rf212 chips.

If you use one channel_set callback as before the change, how would you
overcome the redundancy?

> Btw. I preparing a big cleanup for this driver which supports regmap and
> asychronous handling for rx/tx paths.

Thank you for letting me know. I'm sure I will learn a lot.

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Alexander Aring]

Hi,

On Sun, Jun 01, 2014 at 08:23:17AM -0600, Jean Sacren wrote:
> From: Alexander Aring <alex.aring-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Date: Sun, 01 Jun 2014 09:26:57 +0200
> 
> Hi Alex,
> 
> Thank you very much for the feedback.
> 
> > the at86rf230 driver supports several at86rf2xx chips. You split the
> > at86rf212_set_channel which is at86rf212 specific in two function which
> > are named at86rf230_foo.
> 
> I didn't "split" at86rf212_set_channel() in two functions. I spliced
> those two sections of code and made at86rf212_set_channel() far
> succinct and easy to read.
> 

yes, but this driver supports more than one chip and it's easier to read
if we have one channel_set function for each chip type. Note you also
named the specific channel_set function to a another at86rf230_foo
function which is at86rf212 specific only. Sorry that will confuse
all the people who will ever read this code.

There is a at86rf230_ops and at86rf212_ops struct. The channel_set
function it's much easier to have only one callback for each struct,
otherwise you have 4 different channel_set functions and nobody knows
for which at86rf2xx type that function is for.

> > Sorry, but I think we should not do this. One reason is that the code is
> > much easier to read when we have one channel_set callback for at86rf23x
> > and at86rf212 chips.
> 
> If you use one channel_set callback as before the change, how would you
> overcome the redundancy?
> 

There is no redundancy, sorry. There would be a redundancy if two
chiptypes like at86rf231 and at86rf212 needs some code of this callback
and you can do some codesharing, but you can't do that there.

- Alex

------------------------------------------------------------------------------
Time is money. Stop wasting it! Get your web API in 5 minutes.
www.restlet.com/download
http://p.sf.net/sfu/restlet

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Jean Sacren]

From: Alexander Aring <alex.aring@gmail.com>
Date: Sun, 01 Jun 2014 16:35:53 +0200
>
> Hi,
> 
> On Sun, Jun 01, 2014 at 08:23:17AM -0600, Jean Sacren wrote:
> > From: Alexander Aring <alex.aring@gmail.com>
> > Date: Sun, 01 Jun 2014 09:26:57 +0200
> > 
> > Hi Alex,
> > 
> > Thank you very much for the feedback.
> > 
> > > the at86rf230 driver supports several at86rf2xx chips. You split the
> > > at86rf212_set_channel which is at86rf212 specific in two function which
> > > are named at86rf230_foo.
> > 
> > I didn't "split" at86rf212_set_channel() in two functions. I spliced
> > those two sections of code and made at86rf212_set_channel() far
> > succinct and easy to read.
> > 
> 
> yes, but this driver supports more than one chip and it's easier to read
> if we have one channel_set function for each chip type. Note you also
> named the specific channel_set function to a another at86rf230_foo
> function which is at86rf212 specific only. Sorry that will confuse
> all the people who will ever read this code.
> 
> There is a at86rf230_ops and at86rf212_ops struct. The channel_set
> function it's much easier to have only one callback for each struct,
> otherwise you have 4 different channel_set functions and nobody knows
> for which at86rf2xx type that function is for.

You mean something like the following will be less confusing?

diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
index 4517b149ed07..06b494bacc44 100644
--- a/drivers/net/ieee802154/at86rf230.c
+++ b/drivers/net/ieee802154/at86rf230.c
@@ -602,20 +602,21 @@ at86rf212_set_channel(struct at86rf230_local *lp, int page, int channel)
 {
 	int rc;
 
-	if (channel == 0)
-		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 0);
-	else
-		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 1);
+	if (channel)
+		channel = 1;
+
+	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, channel);
 	if (rc < 0)
 		return rc;
 
-	if (page == 0) {
-		rc = at86rf230_write_subreg(lp, SR_BPSK_QPSK, 0);
-		lp->rssi_base_val = -100;
-	} else {
-		rc = at86rf230_write_subreg(lp, SR_BPSK_QPSK, 1);
+	if (page) {
 		lp->rssi_base_val = -98;
+		page = 1;
+	} else {
+		lp->rssi_base_val = -100;
 	}
+
+	rc = at86rf230_write_subreg(lp, SR_BPSK_QPSK, page);
 	if (rc < 0)
 		return rc;

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Alexander Aring]

On Sun, Jun 01, 2014 at 09:35:47AM -0600, Jean Sacren wrote:
> From: Alexander Aring <alex.aring@gmail.com>
> Date: Sun, 01 Jun 2014 16:35:53 +0200
> >
> > Hi,
> > 
> > On Sun, Jun 01, 2014 at 08:23:17AM -0600, Jean Sacren wrote:
> > > From: Alexander Aring <alex.aring@gmail.com>
> > > Date: Sun, 01 Jun 2014 09:26:57 +0200
> > > 
> > > Hi Alex,
> > > 
> > > Thank you very much for the feedback.
> > > 
> > > > the at86rf230 driver supports several at86rf2xx chips. You split the
> > > > at86rf212_set_channel which is at86rf212 specific in two function which
> > > > are named at86rf230_foo.
> > > 
> > > I didn't "split" at86rf212_set_channel() in two functions. I spliced
> > > those two sections of code and made at86rf212_set_channel() far
> > > succinct and easy to read.
> > > 
> > 
> > yes, but this driver supports more than one chip and it's easier to read
> > if we have one channel_set function for each chip type. Note you also
> > named the specific channel_set function to a another at86rf230_foo
> > function which is at86rf212 specific only. Sorry that will confuse
> > all the people who will ever read this code.
> > 
> > There is a at86rf230_ops and at86rf212_ops struct. The channel_set
> > function it's much easier to have only one callback for each struct,
> > otherwise you have 4 different channel_set functions and nobody knows
> > for which at86rf2xx type that function is for.
> 
> You mean something like the following will be less confusing?

Yes that's less but there are issues and I don't see any reason why we
should do that.

> 
> diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
> index 4517b149ed07..06b494bacc44 100644
> --- a/drivers/net/ieee802154/at86rf230.c
> +++ b/drivers/net/ieee802154/at86rf230.c
> @@ -602,20 +602,21 @@ at86rf212_set_channel(struct at86rf230_local *lp, int page, int channel)
>  {
>  	int rc;
>  
> -	if (channel == 0)
> -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 0);
> -	else
> -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 1);
> +	if (channel)
> +		channel = 1;
> +
> +	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, channel);
>  	if (rc < 0)
>  		return rc;
>  

First:

This will break the at86rf212_set_channel function. At the end of this
function we need the channel parameter and you overwrite it here.
At the end of this function stands:

"return at86rf230_write_subreg(lp, SR_CHANNEL, channel);"

Second:

The variable channel should be a new variable named sub_mode and initialized
to 0, this fixes the first issue.

But again, I don't see any reasons why we should change that. It's the
same thing like before.

- Alex

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Jean Sacren]

From: Alexander Aring <alex.aring@gmail.com>
Date: Sun, 01 Jun 2014 18:39:28 +0200
>
> > You mean something like the following will be less confusing?
> 
> Yes that's less but there are issues and I don't see any reason why we
> should do that.
> 
> > 
> > diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
> > index 4517b149ed07..06b494bacc44 100644
> > --- a/drivers/net/ieee802154/at86rf230.c
> > +++ b/drivers/net/ieee802154/at86rf230.c
> > @@ -602,20 +602,21 @@ at86rf212_set_channel(struct at86rf230_local *lp, int page, int channel)
> >  {
> >  	int rc;
> >  
> > -	if (channel == 0)
> > -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 0);
> > -	else
> > -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 1);
> > +	if (channel)
> > +		channel = 1;
> > +
> > +	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, channel);
> >  	if (rc < 0)
> >  		return rc;
> >  
> 
> First:
> 
> This will break the at86rf212_set_channel function. At the end of this
> function we need the channel parameter and you overwrite it here.
> At the end of this function stands:
> 
> "return at86rf230_write_subreg(lp, SR_CHANNEL, channel);"

You are right, but we can:

	if (channel)
		rc = 1;

	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, rc);

Re: [PATCH net-next] ieee802154: use helper function to get rid of redundancy

[Jean Sacren]

From: Jean Sacren <sakiwit@gmail.com>
Date: Sun, 01 Jun 2014 11:49:29 -0600
>
> From: Alexander Aring <alex.aring@gmail.com>
> Date: Sun, 01 Jun 2014 18:39:28 +0200
> >
> > > You mean something like the following will be less confusing?
> > 
> > Yes that's less but there are issues and I don't see any reason why we
> > should do that.
> > 
> > > 
> > > diff --git a/drivers/net/ieee802154/at86rf230.c b/drivers/net/ieee802154/at86rf230.c
> > > index 4517b149ed07..06b494bacc44 100644
> > > --- a/drivers/net/ieee802154/at86rf230.c
> > > +++ b/drivers/net/ieee802154/at86rf230.c
> > > @@ -602,20 +602,21 @@ at86rf212_set_channel(struct at86rf230_local *lp, int page, int channel)
> > >  {
> > >  	int rc;
> > >  
> > > -	if (channel == 0)
> > > -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 0);
> > > -	else
> > > -		rc = at86rf230_write_subreg(lp, SR_SUB_MODE, 1);
> > > +	if (channel)
> > > +		channel = 1;
> > > +
> > > +	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, channel);
> > >  	if (rc < 0)
> > >  		return rc;
> > >  
> > 
> > First:
> > 
> > This will break the at86rf212_set_channel function. At the end of this
> > function we need the channel parameter and you overwrite it here.
> > At the end of this function stands:
> > 
> > "return at86rf230_write_subreg(lp, SR_CHANNEL, channel);"
> 
> You are right, but we can:
> 
> 	if (channel)
> 		rc = 1;
> 
> 	rc = at86rf230_write_subreg(lp, SR_SUB_MODE, rc);

Obviously:

	int rc = 0;