netdev - Re: [PATCH net-next] net: systemport: avoid build warnings due to unused I/O helpers

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Message-ID: <c5ffe617-e182-4561-95d4-5f635fda53db@broadcom.com>
Date: Mon, 14 Oct 2024 09:56:25 -0700
From: Florian Fainelli <florian.fainelli@...adcom.com>
To: Vladimir Oltean <vladimir.oltean@....com>, netdev@...r.kernel.org
Cc: Broadcom internal kernel review list
 <bcm-kernel-feedback-list@...adcom.com>,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net: systemport: avoid build warnings due to
 unused I/O helpers

On 10/14/24 08:01, Vladimir Oltean wrote:
> A clang-16 W=1 build emits the following (abridged):
> 
> warning: unused function 'txchk_readl' [-Wunused-function]
> BCM_SYSPORT_IO_MACRO(txchk, SYS_PORT_TXCHK_OFFSET);
> note: expanded from macro 'BCM_SYSPORT_IO_MACRO'
> 
> warning: unused function 'txchk_writel' [-Wunused-function]
> note: expanded from macro 'BCM_SYSPORT_IO_MACRO'
> 
> warning: unused function 'tbuf_readl' [-Wunused-function]
> BCM_SYSPORT_IO_MACRO(tbuf, SYS_PORT_TBUF_OFFSET);
> note: expanded from macro 'BCM_SYSPORT_IO_MACRO'
> 
> warning: unused function 'tbuf_writel' [-Wunused-function]
> note: expanded from macro 'BCM_SYSPORT_IO_MACRO'
> 
> Annotate the functions with the __maybe_unused attribute to tell the
> compiler it's fine to do dead code elimination, and suppress the
> warnings.
> 
> Also, remove the "inline" keyword from C files, since the compiler is
> free anyway to inline or not.
> 
> Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>

clang is adequately warning that the txchk_{read,write}l functions are 
not used at all, so while your patch is correct, I think we could also 
go with this one liner in addition, or as a replacement to your patch:

diff --git a/drivers/net/ethernet/broadcom/bcmsysport.c 
b/drivers/net/ethernet/broadcom/bcmsysport.c
index c9faa8540859..7cea30eac83a 100644
--- a/drivers/net/ethernet/broadcom/bcmsysport.c
+++ b/drivers/net/ethernet/broadcom/bcmsysport.c
@@ -46,7 +46,6 @@ BCM_SYSPORT_IO_MACRO(umac, SYS_PORT_UMAC_OFFSET);
  BCM_SYSPORT_IO_MACRO(gib, SYS_PORT_GIB_OFFSET);
  BCM_SYSPORT_IO_MACRO(tdma, SYS_PORT_TDMA_OFFSET);
  BCM_SYSPORT_IO_MACRO(rxchk, SYS_PORT_RXCHK_OFFSET);
-BCM_SYSPORT_IO_MACRO(txchk, SYS_PORT_TXCHK_OFFSET);
  BCM_SYSPORT_IO_MACRO(rbuf, SYS_PORT_RBUF_OFFSET);
  BCM_SYSPORT_IO_MACRO(tbuf, SYS_PORT_TBUF_OFFSET);
  BCM_SYSPORT_IO_MACRO(topctrl, SYS_PORT_TOPCTRL_OFFSET);
-- 
Florian