[net,v2,1/2] dpaa_eth: update the buffer layout for non-A050385 erratum scenarios

Impose a large RX private data area only when the A050385 erratum is
present on the hardware. A smaller buffer size is sufficient in all
other scenarios. This enables a wider range of linear frame sizes
in non-erratum scenarios

Fixes: 3c68b8fffb48 ("dpaa_eth: FMan erratum A050385 workaround")
Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
---
 drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

On Wed, 28 Oct 2020 18:40:59 +0200 Camelia Groza wrote:
> Impose a large RX private data area only when the A050385 erratum is
> present on the hardware. A smaller buffer size is sufficient in all
> other scenarios. This enables a wider range of linear frame sizes
> in non-erratum scenarios

Any word on user impact? Measurable memory waste?

> Fixes: 3c68b8fffb48 ("dpaa_eth: FMan erratum A050385 workaround")
> Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
> ---
>  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> index 06cc863..1aac0b6 100644
> --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c
> @@ -175,8 +175,10 @@
>  #define DPAA_TIME_STAMP_SIZE 8
>  #define DPAA_HASH_RESULTS_SIZE 8
>  #ifdef CONFIG_DPAA_ERRATUM_A050385
> -#define DPAA_RX_PRIV_DATA_SIZE (DPAA_A050385_ALIGN - (DPAA_PARSE_RESULTS_SIZE\
> -	 + DPAA_TIME_STAMP_SIZE + DPAA_HASH_RESULTS_SIZE))
> +#define DPAA_RX_PRIV_DATA_SIZE (fman_has_errata_a050385() ? \
> +			(DPAA_A050385_ALIGN - (DPAA_PARSE_RESULTS_SIZE\
> +			 + DPAA_TIME_STAMP_SIZE + DPAA_HASH_RESULTS_SIZE)) : \
> +			(DPAA_TX_PRIV_DATA_SIZE + dpaa_rx_extra_headroom))

This expressions is highly unreadable, please refactor. Maybe separate
defines for errata and non-errata, and one for the ternary operator?

>  #else
>  #define DPAA_RX_PRIV_DATA_SIZE	(u16)(DPAA_TX_PRIV_DATA_SIZE + \
>  					dpaa_rx_extra_headroom)

> -----Original Message-----

> From: Jakub Kicinski <kuba@kernel.org>

> Sent: Saturday, October 31, 2020 03:41

> To: Camelia Alexandra Groza <camelia.groza@nxp.com>

> Cc: willemdebruijn.kernel@gmail.com; Madalin Bucur (OSS)

> <madalin.bucur@oss.nxp.com>; davem@davemloft.net;

> netdev@vger.kernel.org

> Subject: Re: [PATCH net v2 1/2] dpaa_eth: update the buffer layout for non-

> A050385 erratum scenarios

> 

> On Wed, 28 Oct 2020 18:40:59 +0200 Camelia Groza wrote:

> > Impose a large RX private data area only when the A050385 erratum is

> > present on the hardware. A smaller buffer size is sufficient in all

> > other scenarios. This enables a wider range of linear frame sizes

> > in non-erratum scenarios

> 

> Any word on user impact? Measurable memory waste?


I'll add more details.

> > Fixes: 3c68b8fffb48 ("dpaa_eth: FMan erratum A050385 workaround")

> > Signed-off-by: Camelia Groza <camelia.groza@nxp.com>

> > ---

> >  drivers/net/ethernet/freescale/dpaa/dpaa_eth.c | 6 ++++--

> >  1 file changed, 4 insertions(+), 2 deletions(-)

> >

> > diff --git a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

> b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

> > index 06cc863..1aac0b6 100644

> > --- a/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

> > +++ b/drivers/net/ethernet/freescale/dpaa/dpaa_eth.c

> > @@ -175,8 +175,10 @@

> >  #define DPAA_TIME_STAMP_SIZE 8

> >  #define DPAA_HASH_RESULTS_SIZE 8

> >  #ifdef CONFIG_DPAA_ERRATUM_A050385

> > -#define DPAA_RX_PRIV_DATA_SIZE (DPAA_A050385_ALIGN -

> (DPAA_PARSE_RESULTS_SIZE\

> > -	 + DPAA_TIME_STAMP_SIZE + DPAA_HASH_RESULTS_SIZE))

> > +#define DPAA_RX_PRIV_DATA_SIZE (fman_has_errata_a050385() ? \

> > +			(DPAA_A050385_ALIGN -

> (DPAA_PARSE_RESULTS_SIZE\

> > +			 + DPAA_TIME_STAMP_SIZE +

> DPAA_HASH_RESULTS_SIZE)) : \

> > +			(DPAA_TX_PRIV_DATA_SIZE +

> dpaa_rx_extra_headroom))

> 

> This expressions is highly unreadable, please refactor. Maybe separate

> defines for errata and non-errata, and one for the ternary operator?


Will clean it up. Thanks.

> >  #else

> >  #define DPAA_RX_PRIV_DATA_SIZE	(u16)(DPAA_TX_PRIV_DATA_SIZE + \

> >  					dpaa_rx_extra_headroom)