RE: [PATCH/RFC 2/2] ravb: Add GbEthernet driver support

Hi Geert,

Thanks for the feedback.

Subject: Re: [PATCH/RFC 2/2] ravb: Add GbEthernet driver support

Hi Biju,

On Wed, Jul 14, 2021 at 4:54 PM Biju Das [off-list ref]
wrote:

quoted

Add Gigabit Ethernet driver support.

The Gigabit Etherner IP consists of Ethernet controller (E-MAC),
Internal TCP/IP Offload Engine (TOE) and Dedicated Direct memory
access controller (DMAC).

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>

Thanks for your patch!

quoted

--- a/drivers/net/ethernet/renesas/ravb.h
+++ b/drivers/net/ethernet/renesas/ravb.h

quoted

@@ -986,6 +1068,7 @@ struct ravb_ptp {  enum ravb_chip_id {
        RCAR_GEN2,
        RCAR_GEN3,
+       RZ_G2L,
 };

Instead of adding another chip type, it may be better to replace the chip
type by a structure with feature bits, values, and function pointers (see
examples below).

BTW given the ravb driver is based on the sh_eth driver ("Ethernet AVB
includes an Gigabit Ethernet controller (E-MAC) that is basically
compatible with SuperH Gigabit Ethernet E-MAC"), and seeing the amount of
changes, I'm wondering if rgeth is closer to sh_eth? ;-)

With sh_eth driver,We can reuse only E-MAC IP. But with RAVB we can reuse both DMAC and E-MAC.
Hence I believe it is closer to AVB.

quoted

--- a/drivers/net/ethernet/renesas/ravb_main.c
+++ b/drivers/net/ethernet/renesas/ravb_main.c

quoted

@@ -247,8 +288,12 @@ static void ravb_ring_free(struct net_device *ndev,

int q)

quoted

        int ring_size;
        int i;

-       if (priv->rx_ring[q]) {
-               ravb_ring_free_ex(ndev, q);
+       if (priv->chip_id == RZ_G2L) {
+               if (priv->rgeth_rx_ring[q])
+                       rgeth_ring_free_ex(ndev, q);
+       } else {
+               if (priv->rx_ring[q])
+                       ravb_ring_free_ex(ndev, q);
        }

Could be called through a function pointer instead.

OK.

quoted

@@ -356,7 +434,7 @@ static void ravb_ring_format(struct net_device

*ndev, int q)  static int ravb_ring_init(struct net_device *ndev, int
q)  {
        struct ravb_private *priv = netdev_priv(ndev);
-       size_t skb_sz = RX_BUF_SZ;
+       size_t skb_sz = (priv->chip_id == RZ_G2L) ? RGETH_RCV_BUFF_MAX
+ : RX_BUF_SZ;

Could use a value in the structure.

OK.

quoted

@@ -730,7 +1054,7 @@ static void ravb_emac_interrupt_unlocked(struct

net_device *ndev)

quoted

        ecsr = ravb_read(ndev, ECSR);
        ravb_write(ndev, ecsr, ECSR);   /* clear interrupt */

-       if (ecsr & ECSR_MPD)
+       if (priv->chip_id != RZ_G2L && (ecsr & ECSR_MPD))

Could use a feature bit.

OK.

quoted

@@ -2104,11 +2578,19 @@ static int ravb_probe(struct platform_device

*pdev)

quoted

        priv = netdev_priv(ndev);
        priv->chip_id = chip_id;

-       ndev->features = NETIF_F_RXCSUM;
-       ndev->hw_features = NETIF_F_RXCSUM;
-
-       pm_runtime_enable(&pdev->dev);
-       pm_runtime_get_sync(&pdev->dev);
+       if (chip_id == RZ_G2L) {
+               ndev->hw_features |= (NETIF_F_HW_CSUM | NETIF_F_RXCSUM);
+               priv->rstc = devm_reset_control_get(&pdev->dev, NULL);

R-Car Gen2 and Gen3 describe a reset in DT, too.
Does it hurt to always use the reset?

OK will use reset.

quoted

+               if (IS_ERR(priv->rstc)) {
+                       dev_err(&pdev->dev, "failed to get cpg
+ reset\n");

dev_err_probe(), to avoid printing an error on -EPROBE_DEFER.

OK.


Regards,
Biju

quoted

+                       free_netdev(ndev);
+                       return PTR_ERR(priv->rstc);
+               }
+               reset_control_deassert(priv->rstc);
+       } else {
+               ndev->features = NETIF_F_RXCSUM;
+               ndev->hw_features = NETIF_F_RXCSUM;
+       }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-
m68k.org

In personal conversations with technical people, I call myself a hacker.
But when I'm talking to journalists I just say "programmer" or something
like that.
                                -- Linus Torvalds