net: stmmac: Apply redundant write work around on 4.xx too

commit a3a57bf07de23fe1ff779e0fdf710aa581c3ff73 ("net: stmmac: work
around sporadic tx issue on link-up") worked around a problem with TX
sometimes not working after a link-up by avoiding a redundant write to
MAC_CTRL_REG (aka GMAC_CONFIG), since the IP appeared to have problems
with handling multiple writes to that register in some cases.

That commit however only added the work around to dwmac_lib.c (apart
from the common code in stmmac_main.c), but my systems with version
4.21a of the IP exhibit the same problem, so add the work around to
dwmac4_lib.c too.

Fixes: a3a57bf07de2 ("net: stmmac: work around sporadic tx issue on link-up")
Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/r/20230721-stmmac-tx-workaround-v1-1-9411cbd5ee07@axis.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
index df41eac..03ceb6a 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c
@@ -240,13 +240,15 @@ void stmmac_dwmac4_set_mac_addr(void __iomem *ioaddr, const u8 addr[6],
 void stmmac_dwmac4_set_mac(void __iomem *ioaddr, bool enable)
 {
        u32 value = readl(ioaddr + GMAC_CONFIG);
+       u32 old_val = value;
 
        if (enable)
                value |= GMAC_CONFIG_RE | GMAC_CONFIG_TE;
        else
                value &= ~(GMAC_CONFIG_TE | GMAC_CONFIG_RE);
 
-       writel(value, ioaddr + GMAC_CONFIG);
+       if (value != old_val)
+               writel(value, ioaddr + GMAC_CONFIG);
 }
 
 void stmmac_dwmac4_get_mac_addr(void __iomem *ioaddr, unsigned char *addr,