From: Nicholas Mc Guire <hofrat@xxxxxxxxx>
usleep_range() is called in non-atomic context so there is little point
in setting min==max as the jitter of hrtimer is determined by interruptions
anyway. usleep_range can only perform the intended coalescence if some
room for placing the hrtimer is provided. Given the range of milliseconds
the delay will be 2+ anyway - so make it 2-2.5 ms which gives hrtimers
space to optimize without negatively impacting performance.
Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
---
Problem located with an experimental coccinelle script
./drivers/staging/wilc1000/wilc_wlan.c:411:4-16: WARNING: inefficient usleep_range with range 0 (min==max)
./drivers/staging/wilc1000/wilc_wlan.c:426:4-16: WARNING: inefficient usleep_range with range 0 (min==max)
V2: Based on feedback from Adham Abozaeid <Adham.Abozaeid@xxxxxxxxxxxxx> that
since this is in the transmit path 5ms could impact throughput but adding
500 microseconds should be tolerable.
Patch was compile tested with: x86_64_defconfig + Staging=y,
WILC1000_SDIO=m, WILC1000_SPI=m, WILC1000=m
Patch is against 5.1-rc4 (localversion-next is -next-20190410)
drivers/staging/wilc1000/wilc_wlan.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/staging/wilc1000/wilc_wlan.c b/drivers/staging/wilc1000/wilc_wlan.c
index c238969..42da533 100644
--- a/drivers/staging/wilc1000/wilc_wlan.c
+++ b/drivers/staging/wilc1000/wilc_wlan.c
@@ -408,7 +408,7 @@ void chip_wakeup(struct wilc *wilc)
wilc->hif_func->hif_write_reg(wilc, 1, reg & ~BIT(1));
do {
- usleep_range(2 * 1000, 2 * 1000);
+ usleep_range(2000, 2500);
wilc_get_chipid(wilc, true);
} while (wilc_get_chipid(wilc, true) == 0);
} while (wilc_get_chipid(wilc, true) == 0);
@@ -423,7 +423,7 @@ void chip_wakeup(struct wilc *wilc)
&clk_status_reg);
while ((clk_status_reg & 0x1) == 0) {
- usleep_range(2 * 1000, 2 * 1000);
+ usleep_range(2000, 2500);
wilc->hif_func->hif_read_reg(wilc, 0xf1,
&clk_status_reg);
--
2.1.4
