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Subject[PATCH v2] soundwire: bandwidth allocation: Use hweight32() to calculate set bits
Date
Replace the call to sdw_ch_mask_to_ch() with a call to hweight32().

sdw_ch_mask_to_ch() is counting the number of set bits. The hweight()
family of functions already do this, and they have an advantage of
using a bit-counting instruction if it is available on the target CPU.
This also fixes a potential infinite loop bug in the implementation of
sdw_ch_mask_to_ch().

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
drivers/soundwire/bus.h | 11 -----------
drivers/soundwire/generic_bandwidth_allocation.c | 3 ++-
2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
index 7631ef5e71fb..4ce8d708a39c 100644
--- a/drivers/soundwire/bus.h
+++ b/drivers/soundwire/bus.h
@@ -159,17 +159,6 @@ int sdw_transfer_defer(struct sdw_bus *bus, struct sdw_msg *msg,
int sdw_fill_msg(struct sdw_msg *msg, struct sdw_slave *slave,
u32 addr, size_t count, u16 dev_num, u8 flags, u8 *buf);

-/* Retrieve and return channel count from channel mask */
-static inline int sdw_ch_mask_to_ch(int ch_mask)
-{
- int c = 0;
-
- for (c = 0; ch_mask; ch_mask >>= 1)
- c += ch_mask & 1;
-
- return c;
-}
-
/* Fill transport parameter data structure */
static inline void sdw_fill_xport_params(struct sdw_transport_params *params,
int port_num, bool grp_ctrl_valid,
diff --git a/drivers/soundwire/generic_bandwidth_allocation.c b/drivers/soundwire/generic_bandwidth_allocation.c
index f7c66083a4dd..ea3e8ef408e4 100644
--- a/drivers/soundwire/generic_bandwidth_allocation.c
+++ b/drivers/soundwire/generic_bandwidth_allocation.c
@@ -6,6 +6,7 @@
*
*/

+#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/module.h>
#include <linux/mod_devicetable.h>
@@ -54,7 +55,7 @@ static void sdw_compute_slave_ports(struct sdw_master_runtime *m_rt,
slave_total_ch = 0;

list_for_each_entry(p_rt, &s_rt->port_list, port_node) {
- ch = sdw_ch_mask_to_ch(p_rt->ch_mask);
+ ch = hweight32(p_rt->ch_mask);

sdw_fill_xport_params(&p_rt->transport_params,
p_rt->num, false,
--
2.30.2
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