Re: [PATCH 05/14] EDAC/amd64: Add get_ecc_sym_sz() into pvt->ops

[Yazen Ghannam <yazen.ghannam@amd.com>]

On Mon, Feb 28, 2022 at 09:43:45PM +0530, Naveen Krishna Chatradhi wrote:
> From: Muralidhara M K <muralimk@amd.com>
> 
> Add function pointer for determine_ecc_sym_sz() in pvt->ops and assign
> family specific get_ecc_sym_sz() definitions appropriately.
>

Please include the "why".
 
> Signed-off-by: Muralidhara M K <muralimk@amd.com>
> Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
> ---
> This patch is created by splitting the 5/12th patch in series
> [v7 5/12] https://patchwork.kernel.org/project/linux-edac/patch/20220203174942.31630-6-nchatrad@amd.com/
> 
>  drivers/edac/amd64_edac.c | 49 ++++++++++++++++++++++++---------------
>  drivers/edac/amd64_edac.h |  1 +
>  2 files changed, 31 insertions(+), 19 deletions(-)
> 
> diff --git a/drivers/edac/amd64_edac.c b/drivers/edac/amd64_edac.c
> index 07428a6c7683..69c33eb17e4f 100644
> --- a/drivers/edac/amd64_edac.c
> +++ b/drivers/edac/amd64_edac.c
> @@ -3176,26 +3176,11 @@ static void free_mc_sibling_devs(struct amd64_pvt *pvt)
>  	}
>  }
>  
> -static void determine_ecc_sym_sz(struct amd64_pvt *pvt)
> +static void f1x_determine_ecc_sym_sz(struct amd64_pvt *pvt)
>  {
>  	pvt->ecc_sym_sz = 4;
>  
> -	if (pvt->umc) {
> -		u8 i;
> -
> -		for_each_umc(i) {
> -			/* Check enabled channels only: */
> -			if (pvt->umc[i].sdp_ctrl & UMC_SDP_INIT) {
> -				if (pvt->umc[i].ecc_ctrl & BIT(9)) {
> -					pvt->ecc_sym_sz = 16;
> -					return;
> -				} else if (pvt->umc[i].ecc_ctrl & BIT(7)) {
> -					pvt->ecc_sym_sz = 8;
> -					return;
> -				}
> -			}
> -		}
> -	} else if (pvt->fam >= 0x10) {
> +	if (pvt->fam >= 0x10) {
>  		u32 tmp;
>  
>  		amd64_read_pci_cfg(pvt->F3, EXT_NB_MCA_CFG, &tmp);
> @@ -3209,6 +3194,26 @@ static void determine_ecc_sym_sz(struct amd64_pvt *pvt)
>  	}
>  }
>  
> +static void f17_determine_ecc_sym_sz(struct amd64_pvt *pvt)
> +{
> +	u8 i;
> +
> +	pvt->ecc_sym_sz = 4;
> +
> +	for_each_umc(i) {
> +		/* Check enabled channels only: */
> +		if (pvt->umc[i].sdp_ctrl & UMC_SDP_INIT) {
> +			if (pvt->umc[i].ecc_ctrl & BIT(9)) {
> +				pvt->ecc_sym_sz = 16;
> +				return;
> +			} else if (pvt->umc[i].ecc_ctrl & BIT(7)) {
> +				pvt->ecc_sym_sz = 8;
> +				return;
> +			}
> +		}
> +	}
> +}

We should reconsider if this is needed. The ECC symbol size was needed on
legacy systems to decode the syndrome. The MCA_SYND register includes the
syndrome on Zen-based systems, so the symbol size is only used for a single
pr_info().

Thanks,
Yazen