linux-kernel - Re: [PATCH v2 2/2] e1000e: ignore factory-default checksum value on TGP platform

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Message-ID: <cca5cdd3-79b3-483d-9967-8a134dd23219@jacekk.info>
Date: Tue, 24 Jun 2025 14:51:09 +0200
From: Jacek Kowalski <jacek@...ekk.info>
To: Simon Horman <horms@...nel.org>
Cc: Tony Nguyen <anthony.l.nguyen@...el.com>,
 Przemek Kitszel <przemyslaw.kitszel@...el.com>,
 Andrew Lunn <andrew+netdev@...n.ch>, "David S. Miller"
 <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 intel-wired-lan@...ts.osuosl.org, netdev@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 2/2] e1000e: ignore factory-default checksum value on
 TGP platform

>> +	if (hw->mac.type == e1000_pch_tgp && checksum == (u16)NVM_SUM_FACTORY_DEFAULT) {
> 
> I see that a similar cast is applied to NVM_SUM. But why?
> If it's not necessary then I would advocate dropping it.

It's like that since the beginning of git history, tracing back to e1000:

$ git show 1da177e4c3f4:drivers/net/e1000/e1000_hw.c | grep -A 1 EEPROM_SUM
     if(checksum == (uint16_t) EEPROM_SUM)
         return E1000_SUCCESS;
(...)

I'd really prefer to keep it as-is here for a moment, since similar 
constructs are not only here, and then clean them up separately.

Examples instances from drivers/net/ethernet/intel:

e1000/e1000_ethtool.c:  if ((checksum != (u16)EEPROM_SUM) && !(*data))
e1000/e1000_hw.c:       if (checksum == (u16)EEPROM_SUM)
e1000e/ethtool.c:       if ((checksum != (u16)NVM_SUM) && !(*data))
igb/e1000_82575.c:      if (checksum != (u16) NVM_SUM) {
igb/e1000_nvm.c:        if (checksum != (u16) NVM_SUM) {
igc/igc_nvm.c:  if (checksum != (u16)NVM_SUM) {

-- 
Best regards,
   Jacek Kowalski