RE: [PATCH net] net: enetc: correct the value of ENETC_RXB_TRUESIZE

[Claudiu Manoil]

> -----Original Message-----
> From: Vladimir Oltean <vladimir.oltean@xxxxxxx>
> Sent: Friday, October 10, 2025 3:49 PM
> To: Wei Fang <wei.fang@xxxxxxx>; Claudiu Manoil
> <claudiu.manoil@xxxxxxx>
> Cc: Clark Wang <xiaoning.wang@xxxxxxx>; andrew+netdev@xxxxxxx;
> davem@xxxxxxxxxxxxx; edumazet@xxxxxxxxxx; kuba@xxxxxxxxxx;
> pabeni@xxxxxxxxxx; Frank Li <frank.li@xxxxxxx>; imx@xxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH net] net: enetc: correct the value of ENETC_RXB_TRUESIZE
> 
> On Fri, Oct 10, 2025 at 05:26:08PM +0800, Wei Fang wrote:
> > ENETC_RXB_TRUESIZE indicates the size of half a page, but the page
> > size is adjustable, for ARM64 platform, the PAGE_SIZE can be 4K, 16K
> > and 64K, so a fixed value '2048' is not correct when the PAGE_SIZE is 16K or
> 64K.
> >
> > Fixes: d4fd0404c1c9 ("enetc: Introduce basic PF and VF ENETC ethernet
> > drivers")
> > Signed-off-by: Wei Fang <wei.fang@xxxxxxx>
> > ---
> >  drivers/net/ethernet/freescale/enetc/enetc.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/net/ethernet/freescale/enetc/enetc.h
> > b/drivers/net/ethernet/freescale/enetc/enetc.h
> > index 0ec010a7d640..f279fa597991 100644
> > --- a/drivers/net/ethernet/freescale/enetc/enetc.h
> > +++ b/drivers/net/ethernet/freescale/enetc/enetc.h
> > @@ -76,7 +76,7 @@ struct enetc_lso_t {
> >  #define ENETC_LSO_MAX_DATA_LEN		SZ_256K
> >
> >  #define ENETC_RX_MAXFRM_SIZE	ENETC_MAC_MAXFRM_SIZE
> > -#define ENETC_RXB_TRUESIZE	2048 /* PAGE_SIZE >> 1 */
> > +#define ENETC_RXB_TRUESIZE	(PAGE_SIZE >> 1)
> >  #define ENETC_RXB_PAD		NET_SKB_PAD /* add extra space if
> needed */
> >  #define ENETC_RXB_DMA_SIZE	\
> >  	(SKB_WITH_OVERHEAD(ENETC_RXB_TRUESIZE) - ENETC_RXB_PAD)
> > --
> > 2.34.1
> >
> 
> I wonder why 2048 was preferred, even though PAGE_SIZE >> 1 was in a
> comment.
> Claudiu, do you remember?

Initial driver implementation for enetcv1 was bound to 4k pages, I need to recheck why and get back to you.

Regards,
Claudiu