[PATCH net-next] net: pse-pd: tps23881: Fix the device ID check

[PATCH net-next] net: pse-pd: tps23881: Fix the device ID check

[Kyle Swenson]

The DEVID register contains two pieces of information: the device ID in
the upper nibble, and the silicon revision number in the lower nibble.
The driver should work fine with any silicon revision, so let's mask
that out in the device ID check.

Fixes: 20e6d190ffe1 ("net: pse-pd: Add TI TPS23881 PSE controller driver")
Signed-off-by: Kyle Swenson <kyle.swenson@est.tech>
---
 drivers/net/pse-pd/tps23881.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
index 61f6ad9c1934..bff8402fb382 100644
--- a/drivers/net/pse-pd/tps23881.c
+++ b/drivers/net/pse-pd/tps23881.c
@@ -748,11 +748,11 @@ static int tps23881_i2c_probe(struct i2c_client *client)
 
 	ret = i2c_smbus_read_byte_data(client, TPS23881_REG_DEVID);
 	if (ret < 0)
 		return ret;
 
-	if (ret != 0x22) {
+	if ((ret & 0xF0) != 0x20) {
 		dev_err(dev, "Wrong device ID\n");
 		return -ENXIO;
 	}
 
 	ret = tps23881_flash_sram_fw(client);
-- 
2.43.0

Re: [PATCH net-next] net: pse-pd: tps23881: Fix the device ID check

[Thomas Petazzoni]

Hello Kyle,

On Tue, 30 Jul 2024 16:11:08 +0000
Kyle Swenson <kyle.swenson@est.tech> wrote:

> The DEVID register contains two pieces of information: the device ID in
> the upper nibble, and the silicon revision number in the lower nibble.
> The driver should work fine with any silicon revision, so let's mask
> that out in the device ID check.
> 
> Fixes: 20e6d190ffe1 ("net: pse-pd: Add TI TPS23881 PSE controller driver")
> Signed-off-by: Kyle Swenson <kyle.swenson@est.tech>
> ---
>  drivers/net/pse-pd/tps23881.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
> index 61f6ad9c1934..bff8402fb382 100644
> --- a/drivers/net/pse-pd/tps23881.c
> +++ b/drivers/net/pse-pd/tps23881.c
> @@ -748,11 +748,11 @@ static int tps23881_i2c_probe(struct i2c_client *client)
>  
>  	ret = i2c_smbus_read_byte_data(client, TPS23881_REG_DEVID);
>  	if (ret < 0)
>  		return ret;
>  
> -	if (ret != 0x22) {
> +	if ((ret & 0xF0) != 0x20) {

Thanks for the patch! I believe it would make sense to use defines
here. At least for 0xF0, and perhaps for 0x20 as well.

Maybe:

#define TPS23881_REG_DEVID      		0x43
#define TPS23881_REG_DEVID_DEVID_MASK		0xF0
#define TPS23881_REG_DEVID_DEVID_VAL		0x2

and then:

	if (FIELD_GET(TPS23881_REG_DEVID_DEVID_MASK, ret) != 
            TPS23881_REG_DEVID_DEVID_VAL)

(totally untested, of course)

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com

Re: [PATCH net-next] net: pse-pd: tps23881: Fix the device ID check

[Kyle Swenson]

Hello Thomas,

On Tue, Jul 30, 2024 at 06:18:12PM +0200, Thomas Petazzoni wrote:
> Hello Kyle,
> 
> On Tue, 30 Jul 2024 16:11:08 +0000
> Kyle Swenson <kyle.swenson@est.tech> wrote:
> 
> > The DEVID register contains two pieces of information: the device ID in
> > the upper nibble, and the silicon revision number in the lower nibble.
> > The driver should work fine with any silicon revision, so let's mask
> > that out in the device ID check.
> > 
> > Fixes: 20e6d190ffe1 ("net: pse-pd: Add TI TPS23881 PSE controller driver")
> > Signed-off-by: Kyle Swenson <kyle.swenson@est.tech>
> > ---
> >  drivers/net/pse-pd/tps23881.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
> > index 61f6ad9c1934..bff8402fb382 100644
> > --- a/drivers/net/pse-pd/tps23881.c
> > +++ b/drivers/net/pse-pd/tps23881.c
> > @@ -748,11 +748,11 @@ static int tps23881_i2c_probe(struct i2c_client *client)
> >  
> >  	ret = i2c_smbus_read_byte_data(client, TPS23881_REG_DEVID);
> >  	if (ret < 0)
> >  		return ret;
> >  
> > -	if (ret != 0x22) {
> > +	if ((ret & 0xF0) != 0x20) {
> 
> Thanks for the patch! I believe it would make sense to use defines
> here. At least for 0xF0, and perhaps for 0x20 as well.
> 
> Maybe:
> 
> #define TPS23881_REG_DEVID      		0x43
> #define TPS23881_REG_DEVID_DEVID_MASK		0xF0
> #define TPS23881_REG_DEVID_DEVID_VAL		0x2

Ah, yes, I agree.  I'll make the changes and send out a V2 tomorrow.

> 
> and then:
> 
> 	if (FIELD_GET(TPS23881_REG_DEVID_DEVID_MASK, ret) != 
>             TPS23881_REG_DEVID_DEVID_VAL)
> 
> (totally untested, of course)
> 
> Best regards,
> 
> Thomas
> -- 
> Thomas Petazzoni, co-owner and CEO, Bootlin
> Embedded Linux and Kernel engineering and training
> https://bootlin.com

Thanks so much for the review!

Cheers,
Kyle