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

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

[Thangaraj Samynathan]

A warm reset on boards using an EEPROM-only strap configuration (where
no MAC address is set in the image) can cause the driver to incorrectly
revert to RGMII mode. This occurs because the ENET_CONFIG_LOAD_STARTED
bit may not persist or behave as expected.

Update pci11x1x_strap_get_status() to use revision-specific validation:

- For PCI11x1x A0: Continue using the legacy check (config load started
  or reset protection) to validate the SGMII strap.
- For PCI11x1x B0 and later: Use the newly available
  STRAP_READ_USE_SGMII_EN_ bit in the upper strap register to validate
  the lower SGMII_EN bit.

This ensures the SGMII interface is correctly identified even after a
warm reboot.

Signed-off-by: Thangaraj Samynathan <thangaraj.s@microchip.com>
---
 drivers/net/ethernet/microchip/lan743x_main.c | 11 +++++++----
 drivers/net/ethernet/microchip/lan743x_main.h |  1 +
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/microchip/lan743x_main.c b/drivers/net/ethernet/microchip/lan743x_main.c
index a3845edf0e48..866f6a3da0d9 100644
--- 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_  &&
+	     (cfg_load & GEN_SYS_LOAD_STARTED_REG_ETH_ ||
+	     hw_cfg & HW_CFG_RST_PROTECT_)) ||
+	     (strap & STRAP_READ_USE_SGMII_EN_)) {
 		if (strap & STRAP_READ_SGMII_EN_)
 			adapter->is_sgmii_en = true;
 		else
diff --git a/drivers/net/ethernet/microchip/lan743x_main.h b/drivers/net/ethernet/microchip/lan743x_main.h
index 02a28b709163..160d94a7cee6 100644
--- a/drivers/net/ethernet/microchip/lan743x_main.h
+++ b/drivers/net/ethernet/microchip/lan743x_main.h
@@ -27,6 +27,7 @@
 #define ID_REV_CHIP_REV_MASK_		(0x0000FFFF)
 #define ID_REV_CHIP_REV_A0_		(0x00000000)
 #define ID_REV_CHIP_REV_B0_		(0x00000010)
+#define ID_REV_CHIP_REV_PCI11X1X_A0_	(0x000000A0)
 #define ID_REV_CHIP_REV_PCI11X1X_B0_	(0x000000B0)
 
 #define FPGA_REV			(0x04)
-- 
2.34.1

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

[Jakub Kicinski]

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?

> +	     (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
-- 
pw-bot: cr

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@kernel.org>
> Sent: Tuesday, March 10, 2026 7:16 AM
> To: Thangaraj Samynathan - I53494 <Thangaraj.S@microchip.com>
> Cc: Bryan Whitehead - C21958 <Bryan.Whitehead@microchip.com>;
> UNGLinuxDriver <UNGLinuxDriver@microchip.com>;
> andrew+netdev@lunn.ch; davem@davemloft.net; edumazet@google.com;
> pabeni@redhat.com; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH net-next] net: lan743x: fix SGMII detection on PCI1xxxx
> B0+ during warm reset
> 
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the
> content is safe
> 
> 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