[PATCH net-next 5/5] ethtool: Note common alternate exit condition for interrupt coalescing

[Ben Hutchings <bhutchings@solarflare.com>]

Many implementations ignore the value of max_frames and do not
treat usecs == 0 as special.  Document this as deprecated.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
---
 include/linux/ethtool.h |    6 ++++++
 1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index 42378b3..3829712 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -173,6 +173,12 @@ struct ethtool_eeprom {
  * would cause interrupts to never be generated.  To disable
  * coalescing, set usecs = 0 and max_frames = 1.
  *
+ * Some implementations ignore the value of max_frames and use the
+ * condition:
+ *	time_since_first_completion >= usecs
+ * This is deprecated.  Drivers for hardware that does not support
+ * counting completions should validate that max_frames == !rx_usecs.
+ *
  * Adaptive RX/TX coalescing is an algorithm implemented by some
  * drivers to improve latency under low packet rates and improve
  * throughput under high packet rates.  Some drivers only implement
-- 
1.7.4.4


-- 
Ben Hutchings, Staff Engineer, Solarflare
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.