Re: [PATCH 2/3] net: pse-pd: tps23881: Add support for TPS23881B

[Thomas Wismer <thomas@wismer.xyz>]

Am Mon, 6 Oct 2025 15:05:05 +0200
schrieb Kory Maincent <kory.maincent@bootlin.com>:

> On Sat,  4 Oct 2025 20:03:51 +0200
> Thomas Wismer <thomas@wismer.xyz> wrote:
> 
> > From: Thomas Wismer <thomas.wismer@scs.ch>
> > 
> > The TPS23881B device requires different firmware, but has a more
> > recent ROM firmware. Since no updated firmware has been released
> > yet, the firmware loading step must be skipped. The device runs
> > from its ROM firmware.
> > 
> > Signed-off-by: Thomas Wismer <thomas.wismer@scs.ch>
> > ---
> >  drivers/net/pse-pd/tps23881.c | 65
> > +++++++++++++++++++++++++++-------- 1 file changed, 51
> > insertions(+), 14 deletions(-)
> > 
> > diff --git a/drivers/net/pse-pd/tps23881.c
> > b/drivers/net/pse-pd/tps23881.c index b724b222ab44..f45c08759082
> > 100644 --- a/drivers/net/pse-pd/tps23881.c
> > +++ b/drivers/net/pse-pd/tps23881.c
> > @@ -55,8 +55,6 @@
> >  #define TPS23881_REG_TPON	BIT(0)
> >  #define TPS23881_REG_FWREV	0x41
> >  #define TPS23881_REG_DEVID	0x43
> > -#define TPS23881_REG_DEVID_MASK	0xF0
> > -#define TPS23881_DEVICE_ID	0x02
> >  #define TPS23881_REG_CHAN1_CLASS	0x4c
> >  #define TPS23881_REG_SRAM_CTRL	0x60
> >  #define TPS23881_REG_SRAM_DATA	0x61
> > @@ -1012,8 +1010,28 @@ static const struct pse_controller_ops
> > tps23881_ops = { .pi_get_pw_req = tps23881_pi_get_pw_req,
> >  };
> >  
> > -static const char fw_parity_name[] =
> > "ti/tps23881/tps23881-parity-14.bin"; -static const char
> > fw_sram_name[] = "ti/tps23881/tps23881-sram-14.bin"; +struct
> > tps23881_info {
> > +	u8 dev_id;	/* device ID and silicon revision */
> > +	const char *fw_parity_name;	/* parity code firmware
> > file name */
> > +	const char *fw_sram_name;	/* SRAM code firmware
> > file name */ +};
> > +
> > +enum tps23881_model {
> > +	TPS23881,
> > +	TPS23881B,
> > +};
> > +
> > +static const struct tps23881_info tps23881_info[] = {
> > +	[TPS23881] = {
> > +		.dev_id = 0x22,
> > +		.fw_parity_name =
> > "ti/tps23881/tps23881-parity-14.bin",
> > +		.fw_sram_name = "ti/tps23881/tps23881-sram-14.bin",
> > +	},
> > +	[TPS23881B] = {
> > +		.dev_id = 0x24,
> > +		/* skip SRAM load, ROM firmware already IEEE802.3bt
> > compliant */
> > +	},  
> 
> You are breaking Kyle's patch:
> https://patchwork.kernel.org/project/netdevbpf/patch/20240731154152.4020668-1-kyle.swenson@est.tech/
> 
> You should check only the device id and not the silicon id.

On the TPS23881, the register "DEVICE ID" reads as 0x22 (Device ID number
DID = 0010b, silicon revision number SR = 0010b). On the TPS23881B, 0x24
(DID = 0010b, SR = 0100b) is returned. Both devices report the same
device ID number DID and can only be distinguished by their silicon
revision number SR.

Unfortunately, Kyle's assumption that the driver should work fine with
any silicon revision proved to be wrong. The TPS23881 firmware is not
compatible with the TPS23881B and must not be attempted to be loaded. As
of today, the TPS23881B must be operated using the ROM firmware.

> Regards,