RE: [PATCH net-next] net: lan743x: fix SGMII detection on PCI1xxxx B0+ during warm reset

[Thangaraj.S]

Hi Jakub,
Thanks for reviewing the patch.

> -----Original Message-----
> From: Jakub Kicinski <kuba@xxxxxxxxxx>
> Sent: Tuesday, March 10, 2026 7:16 AM
> To: Thangaraj Samynathan - I53494 <Thangaraj.S@xxxxxxxxxxxxx>
> Cc: Bryan Whitehead - C21958 <Bryan.Whitehead@xxxxxxxxxxxxx>;
> UNGLinuxDriver <UNGLinuxDriver@xxxxxxxxxxxxx>;
> andrew+netdev@xxxxxxx; davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH net-next] net: lan743x: fix SGMII detection on PCI1xxxx
> B0+ during warm reset
> 
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> 
> On Thu, 5 Mar 2026 14:33:55 +0530 Thangaraj Samynathan wrote:
> > --- a/drivers/net/ethernet/microchip/lan743x_main.c
> > +++ b/drivers/net/ethernet/microchip/lan743x_main.c
> > @@ -32,10 +32,12 @@ static void pci11x1x_strap_get_status(struct
> > lan743x_adapter *adapter)  {
> >       u32 chip_rev;
> >       u32 cfg_load;
> > +     u32 dev_rev;
> >       u32 hw_cfg;
> >       u32 strap;
> >       int ret;
> >
> > +     dev_rev = adapter->csr.id_rev & ID_REV_CHIP_REV_MASK_;
> >       /* Timeout = 100 (i.e. 1 sec (10 msce * 100)) */
> >       ret = lan743x_hs_syslock_acquire(adapter, 100);
> >       if (ret < 0) {
> > @@ -47,10 +49,11 @@ static void pci11x1x_strap_get_status(struct
> lan743x_adapter *adapter)
> >       cfg_load = lan743x_csr_read(adapter,
> ETH_SYS_CONFIG_LOAD_STARTED_REG);
> >       lan743x_hs_syslock_release(adapter);
> >       hw_cfg = lan743x_csr_read(adapter, HW_CFG);
> > -
> > -     if (cfg_load & GEN_SYS_LOAD_STARTED_REG_ETH_ ||
> > -         hw_cfg & HW_CFG_RST_PROTECT_) {
> > -             strap = lan743x_csr_read(adapter, STRAP_READ);
> > +     strap = lan743x_csr_read(adapter, STRAP_READ);
> > +     if ((dev_rev == ID_REV_CHIP_REV_PCI11X1X_A0_  &&
> 
> it may be a good idea to a add a little helper like:
> 
> static bool pci11x1x_is_a0(const struct lan743x_adapter *adapter) {
>         u32 dev_rev = adapter->csr.id_rev & ID_REV_CHIP_REV_MASK_;
> 
>         return dev_rev == ID_REV_CHIP_REV_PCI11X1X_A0_; }
> 
> and same thing for b0?

Sure, I will add the helper in the next revision of the patch.
> 
> > +          (cfg_load & GEN_SYS_LOAD_STARTED_REG_ETH_ ||
> > +          hw_cfg & HW_CFG_RST_PROTECT_)) ||
> > +          (strap & STRAP_READ_USE_SGMII_EN_)) {
> 
> I don't think this implements the logic you describe in the commit message?
> You say:
> 
>  For PCI11x1x B0 and later: Use the newly available
>   STRAP_READ_USE_SGMII_EN_
> 
> but your condition will also look at the strap & STRAP_READ_USE_SGMII_EN_
> if cfg_load & GEN_SYS_LOAD_STARTED_REG_ETH_ || hw_cfg &
> HW_CFG_RST_PROTECT_ is also on A0

This bit was introduced in B0, but in the earlier version this bit always reads zero and makes no difference.
> --
> pw-bot: cr

Regards,
Thangaraj Samynathan