[RFC,net-next,02/10] net: stmmac: rename dev_id to userver

The Synopsys Databook and several implementation TRMs identify bits
15:8 of the version register in dwmac v3.xx and v4.xx as "userver".
We even print its value with "User ID". Rather than using "dev_id",
use "userver" instead.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 drivers/net/ethernet/stmicro/stmmac/hwif.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)
  

Hi Russell,

On Wed, Apr 8, 2026 at 2:27 AM Russell King (Oracle)
<rmk+kernel@armlinux.org.uk> wrote:
>
> The Synopsys Databook and several implementation TRMs identify bits
> 15:8 of the version register in dwmac v3.xx and v4.xx as "userver".
> We even print its value with "User ID". Rather than using "dev_id",
> use "userver" instead.
>
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>  drivers/net/ethernet/stmicro/stmmac/hwif.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.c b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> index 3774af66db48..830ff816ab4f 100644
> --- a/drivers/net/ethernet/stmicro/stmmac/hwif.c
> +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> @@ -15,7 +15,7 @@
>
>  struct stmmac_version {
>         u8 snpsver;
> -       u8 dev_id;
> +       u8 userver;
>  };
>From the XGMAC databook that I have access to bits(15:8) identify the
DEVID field of MAC_version register.
The userver field is from bits(23:16) of the same register. This is a
customer defined field (configured with coreConsultant).
Currently stmmac doesn't care about bits(23:16).

I think the confusion is coming from macro name in common.h
#define DWMAC_USERVER   GENMASK_U32(15, 8)
This should be named
#define DWMAC_DEVID   GENMASK_U32(15, 8)
Hope someone with access to another databook can confirm this.

>
>  static void stmmac_get_version(struct stmmac_priv *priv,
> @@ -26,7 +26,7 @@ static void stmmac_get_version(struct stmmac_priv *priv,
>         u32 version;
>
>         ver->snpsver = 0;
> -       ver->dev_id = 0;
> +       ver->userver = 0;
>
>         if (core_type == DWMAC_CORE_MAC100)
>                 return;
> @@ -48,7 +48,7 @@ static void stmmac_get_version(struct stmmac_priv *priv,
>
>         ver->snpsver = FIELD_GET(DWMAC_SNPSVER, version);
>         if (core_type == DWMAC_CORE_XGMAC)
> -               ver->dev_id = FIELD_GET(DWMAC_USERVER, version);
> +               ver->userver = FIELD_GET(DWMAC_USERVER, version);
>  }
>
>  static void stmmac_dwmac_mode_quirk(struct stmmac_priv *priv)
> @@ -111,7 +111,7 @@ int stmmac_reset(struct stmmac_priv *priv)
>  static const struct stmmac_hwif_entry {
>         enum dwmac_core_type core_type;
>         u32 min_snpsver;
> -       u32 dev_id;
> +       u32 userver;
>         const struct stmmac_regs_off regs;
>         const void *desc;
>         const void *dma;
> @@ -247,7 +247,7 @@ static const struct stmmac_hwif_entry {
>         }, {
>                 .core_type = DWMAC_CORE_XGMAC,
>                 .min_snpsver = DWXGMAC_CORE_2_10,
> -               .dev_id = DWXGMAC_ID,
> +               .userver = DWXGMAC_ID,
>                 .regs = {
>                         .ptp_off = PTP_XGMAC_OFFSET,
>                         .mmc_off = MMC_XGMAC_OFFSET,
> @@ -269,7 +269,7 @@ static const struct stmmac_hwif_entry {
>         }, {
>                 .core_type = DWMAC_CORE_XGMAC,
>                 .min_snpsver = DWXLGMAC_CORE_2_00,
> -               .dev_id = DWXLGMAC_ID,
> +               .userver = DWXLGMAC_ID,
>                 .regs = {
>                         .ptp_off = PTP_XGMAC_OFFSET,
>                         .mmc_off = MMC_XGMAC_OFFSET,
> @@ -291,7 +291,7 @@ static const struct stmmac_hwif_entry {
>  };
>
>  static const struct stmmac_hwif_entry *
> -stmmac_hwif_find(enum dwmac_core_type core_type, u8 snpsver, u8 dev_id)
> +stmmac_hwif_find(enum dwmac_core_type core_type, u8 snpsver, u8 userver)
>  {
>         const struct stmmac_hwif_entry *entry;
>         int i;
> @@ -305,7 +305,7 @@ stmmac_hwif_find(enum dwmac_core_type core_type, u8 snpsver, u8 dev_id)
>                 if (snpsver < entry->min_snpsver)
>                         continue;
>                 if (core_type == DWMAC_CORE_XGMAC &&
> -                   dev_id != entry->dev_id)
> +                   userver != entry->userver)
>                         continue;
>
>                 return entry;
> @@ -358,7 +358,7 @@ int stmmac_hwif_init(struct stmmac_priv *priv)
>         /* Fallback to generic HW */
>
>         /* Use synopsys_id var because some setups can override this */
> -       entry = stmmac_hwif_find(core_type, priv->synopsys_id, version.dev_id);
> +       entry = stmmac_hwif_find(core_type, priv->synopsys_id, version.userver);
>         if (!entry) {
>                 dev_err(priv->device,
>                         "Failed to find HW IF (id=0x%x, gmac=%d/%d)\n",
> --
> 2.47.3
>
  

On Thu, Apr 09, 2026 at 04:07:42PM -0700, Jitendra Vegiraju wrote:
> Hi Russell,
> 
> On Wed, Apr 8, 2026 at 2:27 AM Russell King (Oracle)
> <rmk+kernel@armlinux.org.uk> wrote:
> >
> > The Synopsys Databook and several implementation TRMs identify bits
> > 15:8 of the version register in dwmac v3.xx and v4.xx as "userver".
> > We even print its value with "User ID". Rather than using "dev_id",
> > use "userver" instead.
> >
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > ---
> >  drivers/net/ethernet/stmicro/stmmac/hwif.c | 18 +++++++++---------
> >  1 file changed, 9 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.c b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > index 3774af66db48..830ff816ab4f 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > @@ -15,7 +15,7 @@
> >
> >  struct stmmac_version {
> >         u8 snpsver;
> > -       u8 dev_id;
> > +       u8 userver;
> >  };
> From the XGMAC databook that I have access to bits(15:8) identify the
> DEVID field of MAC_version register.
> The userver field is from bits(23:16) of the same register. This is a
> customer defined field (configured with coreConsultant).
> Currently stmmac doesn't care about bits(23:16).

Thanks for the additional information.

I don't have any XGMAC documentation, but this indicates that it differs
between XGMAC and previous cores - GMAC and GMAC4 cores, 15:8 are
documented as userver, and 31:16 are marked as reserved.

Note that the dev_info() also prints 15:8 as "User ID" not "Device ID".

To confirm, is the XGMAC version register at offset 0x20 ? Later GMAC
cores moved it to 0x110.
  

On Fri, Apr 10, 2026 at 1:39 AM Russell King (Oracle)
<linux@armlinux.org.uk> wrote:
>
> On Thu, Apr 09, 2026 at 04:07:42PM -0700, Jitendra Vegiraju wrote:
> > Hi Russell,
> >
> > On Wed, Apr 8, 2026 at 2:27 AM Russell King (Oracle)
> > <rmk+kernel@armlinux.org.uk> wrote:
> > >
> > > The Synopsys Databook and several implementation TRMs identify bits
> > > 15:8 of the version register in dwmac v3.xx and v4.xx as "userver".
> > > We even print its value with "User ID". Rather than using "dev_id",
> > > use "userver" instead.
> > >
> > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > ---
> > >  drivers/net/ethernet/stmicro/stmmac/hwif.c | 18 +++++++++---------
> > >  1 file changed, 9 insertions(+), 9 deletions(-)
> > >
> > > diff --git a/drivers/net/ethernet/stmicro/stmmac/hwif.c b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > > index 3774af66db48..830ff816ab4f 100644
> > > --- a/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > > +++ b/drivers/net/ethernet/stmicro/stmmac/hwif.c
> > > @@ -15,7 +15,7 @@
> > >
> > >  struct stmmac_version {
> > >         u8 snpsver;
> > > -       u8 dev_id;
> > > +       u8 userver;
> > >  };
> > From the XGMAC databook that I have access to bits(15:8) identify the
> > DEVID field of MAC_version register.
> > The userver field is from bits(23:16) of the same register. This is a
> > customer defined field (configured with coreConsultant).
> > Currently stmmac doesn't care about bits(23:16).
>
> Thanks for the additional information.
>
> I don't have any XGMAC documentation, but this indicates that it differs
> between XGMAC and previous cores - GMAC and GMAC4 cores, 15:8 are
> documented as userver, and 31:16 are marked as reserved.
>
> Note that the dev_info() also prints 15:8 as "User ID" not "Device ID".
>
> To confirm, is the XGMAC version register at offset 0x20 ? Later GMAC
> cores moved it to 0x110.
The XGMAC version register is at offset 0x110.

>
> --
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!