[PATCH] net: stmmac: dwmac1000: Disable ACS if enhanced descs are not used

[PATCH] net: stmmac: dwmac1000: Disable ACS if enhanced descs are not used

[Remi Pommarel]

ACS (auto PAD/FCS stripping) removes FCS off 802.3 packets (LLC) so that
there is no need to manually strip it for such packets. The enhanced DMA
descriptors allow to flag LLC packets so that the receiving callback can
use that to strip FCS manually or not. On the other hand, normal
descriptors do not support that.

Thus in order to not truncate LLC packet ACS should be disabled when
using normal DMA descriptors.

Signed-off-by: Remi Pommarel <repk@triplefau.lt>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
index d0356fbd1e43..b468acf03b00 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac1000_core.c
@@ -25,6 +25,7 @@ static void dwmac1000_core_init(struct mac_device_info *hw,
 				struct net_device *dev)
 {
 	void __iomem *ioaddr = hw->pcsr;
+	struct stmmac_priv *priv = netdev_priv(dev);
 	u32 value = readl(ioaddr + GMAC_CONTROL);
 	int mtu = dev->mtu;
 
@@ -35,7 +36,7 @@ static void dwmac1000_core_init(struct mac_device_info *hw,
 	 * Broadcom tags can look like invalid LLC/SNAP packets and cause the
 	 * hardware to truncate packets on reception.
 	 */
-	if (netdev_uses_dsa(dev))
+	if (netdev_uses_dsa(dev) || !priv->plat->enh_desc)
 		value &= ~GMAC_CONTROL_ACS;
 
 	if (mtu > 1500)
-- 
2.25.0


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RE: [PATCH] net: stmmac: dwmac1000: Disable ACS if enhanced descs are not used

[Jose Abreu]

From: Remi Pommarel <repk@triplefau.lt>
Date: Mar/06/2020, 19:30:36 (UTC+00:00)

>  	void __iomem *ioaddr = hw->pcsr;
> +	struct stmmac_priv *priv = netdev_priv(dev);
>  	u32 value = readl(ioaddr + GMAC_CONTROL);
>  	int mtu = dev->mtu;

Please use reverse Christmas tree order and also provide a Fixes tag.

---
Thanks,
Jose Miguel Abreu

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Re: [PATCH] net: stmmac: dwmac1000: Disable ACS if enhanced descs are not used

[Remi Pommarel]

On Sat, Mar 07, 2020 at 05:34:28PM +0000, Jose Abreu wrote:
> From: Remi Pommarel <repk@triplefau.lt>
> Date: Mar/06/2020, 19:30:36 (UTC+00:00)
> 
> >  	void __iomem *ioaddr = hw->pcsr;
> > +	struct stmmac_priv *priv = netdev_priv(dev);
> >  	u32 value = readl(ioaddr + GMAC_CONTROL);
> >  	int mtu = dev->mtu;
> 
> Please use reverse Christmas tree order and also provide a Fixes tag.

Done in v2.

Thanks,
-- 
Remi

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