linux-kernel - Re: [PATCH v3 2/2] e1000e: ignore factory-default checksum value on TGP platform

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Message-ID: <20250624194237.GI1562@horms.kernel.org>
Date: Tue, 24 Jun 2025 20:42:37 +0100
From: Simon Horman <horms@...nel.org>
To: Jacek Kowalski <jacek@...ekk.info>
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, Vlad URSU <vlad@...u.me>
Subject: Re: [PATCH v3 2/2] e1000e: ignore factory-default checksum value on
 TGP platform

On Tue, Jun 24, 2025 at 09:14:40PM +0200, Jacek Kowalski wrote:
> As described by Vitaly Lifshits:
> 
> > Starting from Tiger Lake, LAN NVM is locked for writes by SW, so the
> > driver cannot perform checksum validation and correction. This means
> > that all NVM images must leave the factory with correct checksum and
> > checksum valid bit set.
> 
> Unfortunately some systems have left the factory with an empty checksum.
> NVM is not modifiable on this platform, hence ignore checksum 0xFFFF on
> Tiger Lake systems to work around this.

I think that you need to update the patch description.
As of v3 it's the last word of the checksum that is being checked,
not the entire checksum.

> 
> Signed-off-by: Jacek Kowalski <Jacek@...ekk.info>
> Tested-by: Vlad URSU <vlad@...u.me>
> Fixes: 4051f68318ca9 ("e1000e: Do not take care about recovery NVM checksum")
> Cc: stable@...r.kernel.org
> ---
> v2: new check to fix yet another checksum issue
> v2 -> v3: fix variable bein compared, drop u16 cast
>  drivers/net/ethernet/intel/e1000e/defines.h | 3 +++
>  drivers/net/ethernet/intel/e1000e/nvm.c     | 5 +++++
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/defines.h b/drivers/net/ethernet/intel/e1000e/defines.h
> index 8294a7c4f122..2dcf46080533 100644
> --- a/drivers/net/ethernet/intel/e1000e/defines.h
> +++ b/drivers/net/ethernet/intel/e1000e/defines.h
> @@ -638,6 +638,9 @@
>  /* For checksumming, the sum of all words in the NVM should equal 0xBABA. */
>  #define NVM_SUM                    0xBABA
>  
> +/* Factory-default checksum value */
> +#define NVM_CHECKSUM_FACTORY_DEFAULT 0xFFFF

Perhaps it is too long, but I liked Vlad's suggestion of
naming this NVM_CHECKSUM_WORD_FACTORY_DEFAULT.

> +
>  /* PBA (printed board assembly) number words */
>  #define NVM_PBA_OFFSET_0           8
>  #define NVM_PBA_OFFSET_1           9
> diff --git a/drivers/net/ethernet/intel/e1000e/nvm.c b/drivers/net/ethernet/intel/e1000e/nvm.c
> index e609f4df86f4..56f2434bd00a 100644
> --- a/drivers/net/ethernet/intel/e1000e/nvm.c
> +++ b/drivers/net/ethernet/intel/e1000e/nvm.c
> @@ -558,6 +558,11 @@ s32 e1000e_validate_nvm_checksum_generic(struct e1000_hw *hw)
>  		checksum += nvm_data;
>  	}
>  
> +	if (hw->mac.type == e1000_pch_tgp && nvm_data == NVM_CHECKSUM_FACTORY_DEFAULT) {

Please wrap the line above so it is 80 columns wide or less.

	if (hw->mac.type == e1000_pch_tgp &&
	    nvm_data == NVM_CHECKSUM_FACTORY_DEFAULT) {

> +		e_dbg("Factory-default NVM Checksum on TGP platform - ignoring\n");
> +		return 0;
> +	}
> +
>  	if (checksum != (u16)NVM_SUM) {
>  		e_dbg("NVM Checksum Invalid\n");
>  		return -E1000_ERR_NVM;

-- 
pw-bot: changes-requested