net: stmmac: check txpbl for TSO

Documentation states that TxPBL must be >= 4 to allow TSO support, but
the driver doesn't check this. TxPBL comes from the platform glue code
or DT. Add a check with a warning if platform glue code attempts to
enable TSO support with TxPBL too low.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Link: https://patch.msgid.link/E1w7pu3-0000000Eatz-39ts@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index 3c416fe79c159623c9510ad947a49f1a30617b44..350efbd9d85b753ad3177c14743173c228d73632 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -4388,6 +4388,8 @@ static void stmmac_set_gso_types(struct stmmac_priv *priv, bool tso)
 static void stmmac_set_gso_features(struct net_device *ndev)
 {
        struct stmmac_priv *priv = netdev_priv(ndev);
+       const struct stmmac_dma_cfg *dma_cfg;
+       int txpbl;
 
        if (!(priv->plat->flags & STMMAC_FLAG_TSO_EN))
                return;
@@ -4397,6 +4399,18 @@ static void stmmac_set_gso_features(struct net_device *ndev)
                return;
        }
 
+       /* FIXME:
+        *  STM32MP151 (v4.2 userver v4.0) states that TxPBL must be >= 4. It
+        *  is not clear whether PBLx8 (which multiplies the PBL value by 8)
+        *  influences this.
+        */
+       dma_cfg = priv->plat->dma_cfg;
+       txpbl = dma_cfg->txpbl ?: dma_cfg->pbl;
+       if (txpbl < 4) {
+               dev_warn(priv->device, "txpbl(%d) is too low for TSO\n", txpbl);
+               return;
+       }
+
        ndev->hw_features |= NETIF_F_TSO | NETIF_F_TSO6;
        if (priv->plat->core_type == DWMAC_CORE_GMAC4)
                ndev->hw_features |= NETIF_F_GSO_UDP_L4;