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-rw-r--r--drivers/net/ethernet/sfc/ef10.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c
index 174a92f5fe51..7645a3ce3854 100644
--- a/drivers/net/ethernet/sfc/ef10.c
+++ b/drivers/net/ethernet/sfc/ef10.c
@@ -565,10 +565,17 @@ static int efx_ef10_dimension_resources(struct efx_nic *efx)
* several of each (in fact that's the only option if host
* page size is >4K). So we may allocate some extra VIs just
* for writing PIO buffers through.
+ *
+ * The UC mapping contains (min_vis - 1) complete VIs and the
+ * first half of the next VI. Then the WC mapping begins with
+ * the second half of this last VI.
*/
uc_mem_map_size = PAGE_ALIGN((min_vis - 1) * EFX_VI_PAGE_SIZE +
ER_DZ_TX_PIOBUF);
if (nic_data->n_piobufs) {
+ /* pio_write_vi_base rounds down to give the number of complete
+ * VIs inside the UC mapping.
+ */
pio_write_vi_base = uc_mem_map_size / EFX_VI_PAGE_SIZE;
wc_mem_map_size = (PAGE_ALIGN((pio_write_vi_base +
nic_data->n_piobufs) *