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Date:   Wed, 12 Aug 2020 20:37:01 +0100
From:   Jonathan McDowell <noodles@earth.li>
To:     Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        David Miller <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net 1/2] net: stmmac: dwmac1000: provide multicast filter
 fallback
Message-ID: <69708c8942a1f3717d15da861609344bd9a16bae.1597260787.git.noodles@earth.li>
References: <cover.1597260787.git.noodles@earth.li>
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If we don't have a hardware multicast filter available then instead of
silently failing to listen for the requested ethernet broadcast
addresses fall back to receiving all multicast packets, in a similar
fashion to other drivers with no multicast filter.

Cc: stable@vger.kernel.org
Signed-off-by: Jonathan McDowell <noodles@earth.li>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
index efc6ec1b8027..fc8759f146c7 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
@@ -164,6 +164,9 @@ static void dwmac1000_set_filter(struct mac_device_info *hw,
 		value = GMAC_FRAME_FILTER_PR | GMAC_FRAME_FILTER_PCF;
 	} else if (dev->flags & IFF_ALLMULTI) {
 		value = GMAC_FRAME_FILTER_PM;	/* pass all multi */
+	} else if (!netdev_mc_empty(dev) && (mcbitslog2 == 0)) {
+		/* Fall back to all multicast if we've no filter */
+		value = GMAC_FRAME_FILTER_PM;
 	} else if (!netdev_mc_empty(dev)) {
 		struct netdev_hw_addr *ha;
 
-- 
2.20.1