--- Begin Message ---
- To: <vkoul@xxxxxxxxxx>
- Subject: [PATCH v2] soundwire: bandwidth allocation: Use hweight32() to calculate set bits
- From: Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
- Date: Wed, 15 Mar 2023 14:50:51 +0000
- Cc: yung-chuan.liao@xxxxxxxxxxxxxxx, pierre-louis.bossart@xxxxxxxxxxxxxxx, sanyog.r.kale@xxxxxxxxx, alsa-devel@xxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, patches@xxxxxxxxxxxxxxxxxxxxx, Richard Fitzgerald <rf@xxxxxxxxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxx> --- 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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