[PATCH net-next 7/8] ice: move prefetch enable to ice_setup_rx_ctx

Jacob Keller
2024-10-11T18:50:09Z

The ice_write_rxq_ctx() function is responsible for programming the Rx
Queue context into hardware. It receives the configuration in unpacked form
via the ice_rlan_ctx structure.

This function unconditionally modifies the context to set the prefetch
enable bit. This was done by commit c31a5c25bb19 ("ice: Always set prefena
when configuring an Rx queue"). Setting this bit makes sense, since
prefetching descriptors is almost always the preferred behavior.

However, the ice_write_rxq_ctx() function is not the place that actually
defines the queue context. We initialize the Rx Queue context in
ice_setup_rx_ctx(). It is surprising to have the Rx queue context changed
by a function who's responsibility is to program the given context to
hardware.

Following the principle of least surprise, move the setting of the prefetch
enable bit out of ice_write_rxq_ctx() and into the ice_setup_rx_ctx().

Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
---
drivers/net/ethernet/intel/ice/ice_base.c | 3 +++
drivers/net/ethernet/intel/ice/ice_common.c | 9 +++------
2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_base.c b/drivers/net/ethernet/intel/ice/ice_base.c
index 9fb7761bad57..c9b2170a3f5c 100644
--- a/drivers/net/ethernet/intel/ice/ice_base.c
+++ b/drivers/net/ethernet/intel/ice/ice_base.c
@@ -453,6 +453,9 @@ static int ice_setup_rx_ctx(struct ice_rx_ring *ring)
/* Rx queue threshold in units of 64 */
rlan_ctx.lrxqthresh = 1;

+ /* Enable descriptor prefetch */
+ rlan_ctx.prefena = 1;
+
/* PF acts as uplink for switchdev; set flex descriptor with src_vsi
* metadata and flags to allow redirecting to PR netdev
*/
diff --git a/drivers/net/ethernet/intel/ice/ice_common.c b/drivers/net/ethernet/intel/ice/ice_common.c
index 87db31b57c50..67e5f8729dc4 100644
--- a/drivers/net/ethernet/intel/ice/ice_common.c
+++ b/drivers/net/ethernet/intel/ice/ice_common.c
@@ -1435,14 +1435,13 @@ void __ice_pack_rxq_ctx(const struct ice_rlan_ctx *ctx, void *buf, size_t len)
}

/**
- * ice_write_rxq_ctx
+ * ice_write_rxq_ctx - Write Rx Queue context to hardware
* @hw: pointer to the hardware structure
* @rlan_ctx: pointer to the rxq context
* @rxq_index: the index of the Rx queue
*
- * Converts rxq context from sparse to dense structure and then writes
- * it to HW register space and enables the hardware to prefetch descriptors
- * instead of only fetching them on demand
+ * Pack the sparse Rx Queue context into dense hardware format and write it
+ * into the HW register space.
*/
int ice_write_rxq_ctx(struct ice_hw *hw, struct ice_rlan_ctx *rlan_ctx,
u32 rxq_index)
@@ -1452,8 +1451,6 @@ int ice_write_rxq_ctx(struct ice_hw *hw, struct ice_rlan_ctx *rlan_ctx,
if (!rlan_ctx)
return -EINVAL;

- rlan_ctx->prefena = 1;
-
ice_pack_rxq_ctx(rlan_ctx, ctx_buf);

return ice_copy_rxq_ctx_to_hw(hw, ctx_buf, rxq_index);

--
2.47.0.265.g4ca455297942