From 7e975caa0f7bf2f83a5e18b4ae69c3d7fff4eafa Mon Sep 17 00:00:00 2001 From: "Russell King (Oracle)" Date: Tue, 11 Nov 2025 11:26:34 +0000 Subject: [PATCH] net: stmmac: improve ndev->max_mtu setup readability Improve the readibility of the code setting ndev->max_mtu. This depends on the hardware specific maximum defined by the MAC core, and also a platform provided maximum. The code was originally checking that the platform specific maximum was between ndev->min_mtu..MAC core maximum before reducing ndev->max_mtu, otherwise if the platform specific maximum was less than ndev->min_mtu, issuing a warning. Re-order the code to handle the case where the platform specific max is below ndev->min_mtu, which then means that the subsequent test is simply reducing ndev->max_mtu. Update the comment, and add a few blank lines to separate the blocks of code. Signed-off-by: Russell King (Oracle) Link: https://patch.msgid.link/E1vImWA-0000000DrIl-1HZY@rmk-PC.armlinux.org.uk Signed-off-by: Jakub Kicinski --- .../net/ethernet/stmicro/stmmac/stmmac_main.c | 22 ++++++++++--------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index ccf383b355e75..eb43501939962 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -1392,9 +1392,9 @@ static unsigned int stmmac_rx_offset(struct stmmac_priv *priv) return NET_SKB_PAD; } -static int stmmac_set_bfsize(int mtu, int bufsize) +static int stmmac_set_bfsize(int mtu) { - int ret = bufsize; + int ret; if (mtu >= BUF_SIZE_8KiB) ret = BUF_SIZE_16KiB; @@ -3958,12 +3958,13 @@ stmmac_setup_dma_desc(struct stmmac_priv *priv, unsigned int mtu) return ERR_PTR(-ENOMEM); } + /* Returns 0 or BUF_SIZE_16KiB if mtu > 8KiB and dwmac4 or ring mode */ bfsize = stmmac_set_16kib_bfsize(priv, mtu); if (bfsize < 0) bfsize = 0; if (bfsize < BUF_SIZE_16KiB) - bfsize = stmmac_set_bfsize(mtu, 0); + bfsize = stmmac_set_bfsize(mtu); dma_conf->dma_buf_sz = bfsize; /* Chose the tx/rx size from the already defined one in the @@ -7773,22 +7774,23 @@ int stmmac_dvr_probe(struct device *device, /* MTU range: 46 - hw-specific max */ ndev->min_mtu = ETH_ZLEN - ETH_HLEN; + if (priv->plat->core_type == DWMAC_CORE_XGMAC) ndev->max_mtu = XGMAC_JUMBO_LEN; - else if ((priv->plat->enh_desc) || (priv->synopsys_id >= DWMAC_CORE_4_00)) + else if (priv->plat->enh_desc || priv->synopsys_id >= DWMAC_CORE_4_00) ndev->max_mtu = JUMBO_LEN; else ndev->max_mtu = SKB_MAX_HEAD(NET_SKB_PAD + NET_IP_ALIGN); - /* Will not overwrite ndev->max_mtu if plat->maxmtu > ndev->max_mtu - * as well as plat->maxmtu < ndev->min_mtu which is a invalid range. + + /* Warn if the platform's maxmtu is smaller than the minimum MTU, + * otherwise clamp the maximum MTU above to the platform's maxmtu. */ - if ((priv->plat->maxmtu < ndev->max_mtu) && - (priv->plat->maxmtu >= ndev->min_mtu)) - ndev->max_mtu = priv->plat->maxmtu; - else if (priv->plat->maxmtu < ndev->min_mtu) + if (priv->plat->maxmtu < ndev->min_mtu) dev_warn(priv->device, "%s: warning: maxmtu having invalid value (%d)\n", __func__, priv->plat->maxmtu); + else if (priv->plat->maxmtu < ndev->max_mtu) + ndev->max_mtu = priv->plat->maxmtu; ndev->priv_flags |= IFF_LIVE_ADDR_CHANGE; -- 2.47.3