Re: [dpdk-dev] [PATCH] net/ice: fix queue bind MSI-X interrupt error

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 2/19/2020 10:17 AM, taox.zhu@intel.com wrote:
> From: Zhu Tao <taox.zhu@intel.com>
> 
> To bind a queue to an MSI-X interrupt, need to set some register.
> The register consists of many parts, each of which has several
> bits; therefore, the shift operator '<<' was used; so the operator
> '<' in the code should be '<<'.
> 
> Old code adds 1 on even MSI-X interrupt vector index used by queue,
> resulting in interrupt mapping error.
> 
> Fixes: 65dfc889d8 ("net/ice: support Rx queue interruption")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Zhu Tao <taox.zhu@intel.com>
> ---
>  drivers/net/ice/ice_ethdev.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ice/ice_ethdev.c b/drivers/net/ice/ice_ethdev.c
> index 8e9369e0a..85ef83e92 100644
> --- a/drivers/net/ice/ice_ethdev.c
> +++ b/drivers/net/ice/ice_ethdev.c
> @@ -2605,9 +2605,9 @@ __vsi_queues_bind_intr(struct ice_vsi *vsi, uint16_t msix_vect,
>  	for (i = 0; i < nb_queue; i++) {
>  		/*do actual bind*/
>  		val = (msix_vect & QINT_RQCTL_MSIX_INDX_M) |
> -		      (0 < QINT_RQCTL_ITR_INDX_S) | QINT_RQCTL_CAUSE_ENA_M;
> +		      (0 << QINT_RQCTL_ITR_INDX_S) | QINT_RQCTL_CAUSE_ENA_M;
>  		val_tx = (msix_vect & QINT_TQCTL_MSIX_INDX_M) |
> -			 (0 < QINT_TQCTL_ITR_INDX_S) | QINT_TQCTL_CAUSE_ENA_M;
> +			 (0 << QINT_TQCTL_ITR_INDX_S) | QINT_TQCTL_CAUSE_ENA_M;

Hi Tao,

Out of curiosity, what is the point of left shifting "0"?