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Subject[PATCH net-next 1/3] net: ipa: rework ipa_aggr_granularity_val()
Date
The timer used for aggregation makes use of an internal 32 KHz clock.
The granularity of the timer is programmed by a field whose value is
computed by ipa_aggr_granularity_val(). Redefine the way that value
is computed by using a new TIMER_FREQUENCY constant representing the
underlying clock frequency.

Add two BUILD_BUG_ON() calls to ensure the value used is valid.

Signed-off-by: Alex Elder <elder@linaro.org>
---
drivers/net/ipa/ipa_main.c | 5 +++++
drivers/net/ipa/ipa_reg.h | 17 ++++++++---------
2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 76d5108b8403..27a869df3a4b 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -674,6 +674,11 @@ static void ipa_validate_build(void)

/* This is used as a divisor */
BUILD_BUG_ON(!IPA_AGGR_GRANULARITY);
+
+ /* Aggregation granularity value can't be 0, and must fit */
+ BUILD_BUG_ON(!ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY));
+ BUILD_BUG_ON(ipa_aggr_granularity_val(IPA_AGGR_GRANULARITY) >
+ field_max(AGGR_GRANULARITY));
#endif /* IPA_VALIDATE */
}

diff --git a/drivers/net/ipa/ipa_reg.h b/drivers/net/ipa/ipa_reg.h
index 0a688d8c1d7c..7ae8015798ae 100644
--- a/drivers/net/ipa/ipa_reg.h
+++ b/drivers/net/ipa/ipa_reg.h
@@ -190,24 +190,23 @@ static inline u32 ipa_reg_bcr_val(enum ipa_version version)
return 0x00000000;
}

-
#define IPA_REG_LOCAL_PKT_PROC_CNTXT_BASE_OFFSET 0x000001e8

#define IPA_REG_AGGR_FORCE_CLOSE_OFFSET 0x000001ec
/* ipa->available defines the valid bits in the AGGR_FORCE_CLOSE register */

+/* The internal inactivity timer clock is used for the aggregation timer */
+#define TIMER_FREQUENCY 32000 /* 32 KHz inactivity timer clock */
+
#define IPA_REG_COUNTER_CFG_OFFSET 0x000001f0
#define AGGR_GRANULARITY GENMASK(8, 4)
-/* Compute the value to use in the AGGR_GRANULARITY field representing
- * the given number of microseconds (up to 1 millisecond).
- * x = (32 * usec) / 1000 - 1
+/* Compute the value to use in the AGGR_GRANULARITY field representing the
+ * given number of microseconds. The value is one less than the number of
+ * timer ticks in the requested period. Zero not a valid granularity value.
*/
-static inline u32 ipa_aggr_granularity_val(u32 microseconds)
+static inline u32 ipa_aggr_granularity_val(u32 usec)
{
- /* assert(microseconds >= 16); (?) */
- /* assert(microseconds <= 1015); */
-
- return DIV_ROUND_CLOSEST(32 * microseconds, 1000) - 1;
+ return DIV_ROUND_CLOSEST(usec * TIMER_FREQUENCY, USEC_PER_SEC) - 1;
}

#define IPA_REG_TX_CFG_OFFSET 0x000001fc
--
2.25.1
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