[PATCH v2 1/2] media: ir-kbd-i2c: convert to i2c_new_dummy_device()

[PATCH v2 1/2] media: ir-kbd-i2c: convert to i2c_new_dummy_device()

[Wolfram Sang]

Convert this driver to use the new i2c_new_dummy_device() call and bail
out if the dummy device cannot be registered to make failure more
visible to the user.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---

Change since v1:

* reworded commit message because there was no NULL ptr access

 drivers/media/i2c/ir-kbd-i2c.c | 13 +++++--------
 1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/media/i2c/ir-kbd-i2c.c b/drivers/media/i2c/ir-kbd-i2c.c
index 876d7587a1da..f46717052efc 100644
--- a/drivers/media/i2c/ir-kbd-i2c.c
+++ b/drivers/media/i2c/ir-kbd-i2c.c
@@ -885,9 +885,12 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	INIT_DELAYED_WORK(&ir->work, ir_work);
 
 	if (probe_tx) {
-		ir->tx_c = i2c_new_dummy(client->adapter, 0x70);
-		if (!ir->tx_c) {
+		ir->tx_c = devm_i2c_new_dummy_device(&client->dev,
+						     client->adapter, 0x70);
+		if (IS_ERR(ir->tx_c)) {
 			dev_err(&client->dev, "failed to setup tx i2c address");
+			err = PTR_ERR(ir->tx_c);
+			goto err_out_free;
 		} else if (!zilog_init(ir)) {
 			ir->carrier = 38000;
 			ir->duty_cycle = 40;
@@ -904,9 +907,6 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	return 0;
 
  err_out_free:
-	if (ir->tx_c)
-		i2c_unregister_device(ir->tx_c);
-
 	/* Only frees rc if it were allocated internally */
 	rc_free_device(rc);
 	return err;
@@ -919,9 +919,6 @@ static int ir_remove(struct i2c_client *client)
 	/* kill outstanding polls */
 	cancel_delayed_work_sync(&ir->work);
 
-	if (ir->tx_c)
-		i2c_unregister_device(ir->tx_c);
-
 	/* unregister device */
 	rc_unregister_device(ir->rc);
 
-- 
2.20.1

Re: [PATCH v2 1/2] media: ir-kbd-i2c: convert to i2c_new_dummy_device()

[Mauro Carvalho Chehab]

Em Tue, 30 Jul 2019 19:55:54 +0200
Wolfram Sang <wsa+renesas@sang-engineering.com> escreveu:

> Convert this driver to use the new i2c_new_dummy_device() call and bail
> out if the dummy device cannot be registered to make failure more
> visible to the user.
> 

Please don't do that.

At first glance, devm_* sounds a good idea, but we had enough issues
using it on media system.

I don't mind mind much if some SoC specific would use it, but doing
it on generic drivers is a very bad idea. We have removed almost all
devm_* calls from the media system.

The problem with devm is that it the de-allocation routines aren't
called during device unbind. They happen a way later, only when the
device itself is physically removed, or the driver is removed.

That caused lots of headaches to debug memory lifetime issues on
media.

> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> ---
> 
> Change since v1:
> 
> * reworded commit message because there was no NULL ptr access
> 
>  drivers/media/i2c/ir-kbd-i2c.c | 13 +++++--------
>  1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/i2c/ir-kbd-i2c.c b/drivers/media/i2c/ir-kbd-i2c.c
> index 876d7587a1da..f46717052efc 100644
> --- a/drivers/media/i2c/ir-kbd-i2c.c
> +++ b/drivers/media/i2c/ir-kbd-i2c.c
> @@ -885,9 +885,12 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	INIT_DELAYED_WORK(&ir->work, ir_work);
>  
>  	if (probe_tx) {
> -		ir->tx_c = i2c_new_dummy(client->adapter, 0x70);
> -		if (!ir->tx_c) {
> +		ir->tx_c = devm_i2c_new_dummy_device(&client->dev,
> +						     client->adapter, 0x70);
> +		if (IS_ERR(ir->tx_c)) {
>  			dev_err(&client->dev, "failed to setup tx i2c address");
> +			err = PTR_ERR(ir->tx_c);
> +			goto err_out_free;
>  		} else if (!zilog_init(ir)) {
>  			ir->carrier = 38000;
>  			ir->duty_cycle = 40;
> @@ -904,9 +907,6 @@ static int ir_probe(struct i2c_client *client, const struct i2c_device_id *id)
>  	return 0;
>  
>   err_out_free:
> -	if (ir->tx_c)
> -		i2c_unregister_device(ir->tx_c);
> -
>  	/* Only frees rc if it were allocated internally */
>  	rc_free_device(rc);
>  	return err;
> @@ -919,9 +919,6 @@ static int ir_remove(struct i2c_client *client)
>  	/* kill outstanding polls */
>  	cancel_delayed_work_sync(&ir->work);
>  
> -	if (ir->tx_c)
> -		i2c_unregister_device(ir->tx_c);
> -
>  	/* unregister device */
>  	rc_unregister_device(ir->rc);
>  



Thanks,
Mauro

Re: [PATCH v2 1/2] media: ir-kbd-i2c: convert to i2c_new_dummy_device()

[Sean Young]

On Sat, Aug 03, 2019 at 01:17:49PM -0300, Mauro Carvalho Chehab wrote:
> Em Tue, 30 Jul 2019 19:55:54 +0200
> Wolfram Sang <wsa+renesas@sang-engineering.com> escreveu:
> 
> > Convert this driver to use the new i2c_new_dummy_device() call and bail
> > out if the dummy device cannot be registered to make failure more
> > visible to the user.
> > 
> 
> Please don't do that.
> 
> At first glance, devm_* sounds a good idea, but we had enough issues
> using it on media system.
> 
> I don't mind mind much if some SoC specific would use it, but doing
> it on generic drivers is a very bad idea. We have removed almost all
> devm_* calls from the media system.
> 
> The problem with devm is that it the de-allocation routines aren't
> called during device unbind. They happen a way later, only when the
> device itself is physically removed, or the driver is removed.

Yes, good point.

> That caused lots of headaches to debug memory lifetime issues on
> media.

Indeed this becomes much more complex. Explicit freeing is much better.


Thanks,
Sean

[PATCH v2 2/2] media: ir-kbd-i2c: remove outdated comments

[Wolfram Sang]

The "free memory" comment is obsolete since 2013 and the other ones
explain the obvious. Just remove the comments.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
Change since v1:

* none

 drivers/media/i2c/ir-kbd-i2c.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/media/i2c/ir-kbd-i2c.c b/drivers/media/i2c/ir-kbd-i2c.c
index f46717052efc..30fde0e025c9 100644
--- a/drivers/media/i2c/ir-kbd-i2c.c
+++ b/drivers/media/i2c/ir-kbd-i2c.c
@@ -916,13 +916,9 @@ static int ir_remove(struct i2c_client *client)
 {
 	struct IR_i2c *ir = i2c_get_clientdata(client);
 
-	/* kill outstanding polls */
 	cancel_delayed_work_sync(&ir->work);
-
-	/* unregister device */
 	rc_unregister_device(ir->rc);
 
-	/* free memory */
 	return 0;
 }
 
-- 
2.20.1