This is a note to let you know that I've just added the patch titled net: stmmac: Apply redundant write work around on 4.xx too to the 6.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-stmmac-apply-redundant-write-work-around-on-4.xx.patch and it can be found in the queue-6.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit aa786dcc7951728865bf387d921e8f3a70035154 Author: Vincent Whitchurch <vincent.whitchurch@xxxxxxxx> Date: Fri Jul 21 15:39:20 2023 +0200 net: stmmac: Apply redundant write work around on 4.xx too [ Upstream commit 284779dbf4e98753458708783af8c35630674a21 ] 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@xxxxxxxx> Reviewed-by: Simon Horman <simon.horman@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20230721-stmmac-tx-workaround-v1-1-9411cbd5ee07@xxxxxxxx Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c b/drivers/net/ethernet/stmicro/stmmac/dwmac4_lib.c index df41eac54058f..03ceb6a940732 100644 --- 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,