From 2f8fdcb0a73a1831cc4f205f23493a17c0e5536f Mon Sep 17 00:00:00 2001 From: Michal Schmidt Date: Wed, 12 Apr 2023 10:19:24 +0200 Subject: ice: do not busy-wait to read GNSS data The ice-gnss- kernel thread, which reads data from the u-blox GNSS module, keep a CPU core almost 100% busy. The main reason is that it busy-waits for data to become available. A simple improvement would be to replace the "mdelay(10);" in ice_gnss_read() with sleeping. A better fix is to not do any waiting directly in the function and just requeue this delayed work as needed. The advantage is that canceling the work from ice_gnss_exit() becomes immediate, rather than taking up to ~2.5 seconds (ICE_MAX_UBX_READ_TRIES * 10 ms). This lowers the CPU usage of the ice-gnss- thread on my system from ~90 % to ~8 %. I am not sure if the larger 0.1 s pause after inserting data into the gnss subsystem is really necessary, but I'm keeping that as it was. Of course, ideally the driver would not have to poll at all, but I don't know if the E810 can watch for GNSS data availability over the i2c bus by itself and notify the driver. Signed-off-by: Michal Schmidt Reviewed-by: Arkadiusz Kubalewski Reviewed-by: Simon Horman Tested-by: Sunitha Mekala (A Contingent worker at Intel) Signed-off-by: Tony Nguyen --- drivers/net/ethernet/intel/ice/ice_gnss.c | 42 ++++++++++++++----------------- 1 file changed, 19 insertions(+), 23 deletions(-) (limited to 'drivers/net/ethernet/intel/ice/ice_gnss.c') diff --git a/drivers/net/ethernet/intel/ice/ice_gnss.c b/drivers/net/ethernet/intel/ice/ice_gnss.c index 8dec748bb53a..2ea8a2b11bcd 100644 --- a/drivers/net/ethernet/intel/ice/ice_gnss.c +++ b/drivers/net/ethernet/intel/ice/ice_gnss.c @@ -117,6 +117,7 @@ static void ice_gnss_read(struct kthread_work *work) { struct gnss_serial *gnss = container_of(work, struct gnss_serial, read_work.work); + unsigned long delay = ICE_GNSS_POLL_DATA_DELAY_TIME; unsigned int i, bytes_read, data_len, count; struct ice_aqc_link_topo_addr link_topo; struct ice_pf *pf; @@ -136,11 +137,6 @@ static void ice_gnss_read(struct kthread_work *work) return; hw = &pf->hw; - buf = (char *)get_zeroed_page(GFP_KERNEL); - if (!buf) { - err = -ENOMEM; - goto exit; - } memset(&link_topo, 0, sizeof(struct ice_aqc_link_topo_addr)); link_topo.topo_params.index = ICE_E810T_GNSS_I2C_BUS; @@ -151,25 +147,24 @@ static void ice_gnss_read(struct kthread_work *work) i2c_params = ICE_GNSS_UBX_DATA_LEN_WIDTH | ICE_AQC_I2C_USE_REPEATED_START; - /* Read data length in a loop, when it's not 0 the data is ready */ - for (i = 0; i < ICE_MAX_UBX_READ_TRIES; i++) { - err = ice_aq_read_i2c(hw, link_topo, ICE_GNSS_UBX_I2C_BUS_ADDR, - cpu_to_le16(ICE_GNSS_UBX_DATA_LEN_H), - i2c_params, (u8 *)&data_len_b, NULL); - if (err) - goto exit_buf; + err = ice_aq_read_i2c(hw, link_topo, ICE_GNSS_UBX_I2C_BUS_ADDR, + cpu_to_le16(ICE_GNSS_UBX_DATA_LEN_H), + i2c_params, (u8 *)&data_len_b, NULL); + if (err) + goto requeue; - data_len = be16_to_cpu(data_len_b); - if (data_len != 0 && data_len != U16_MAX) - break; + data_len = be16_to_cpu(data_len_b); + if (data_len == 0 || data_len == U16_MAX) + goto requeue; - mdelay(10); - } + /* The u-blox has data_len bytes for us to read */ data_len = min_t(typeof(data_len), data_len, PAGE_SIZE); - if (!data_len) { + + buf = (char *)get_zeroed_page(GFP_KERNEL); + if (!buf) { err = -ENOMEM; - goto exit_buf; + goto requeue; } /* Read received data */ @@ -183,7 +178,7 @@ static void ice_gnss_read(struct kthread_work *work) cpu_to_le16(ICE_GNSS_UBX_EMPTY_DATA), bytes_read, &buf[i], NULL); if (err) - goto exit_buf; + goto free_buf; } count = gnss_insert_raw(pf->gnss_dev, buf, i); @@ -191,10 +186,11 @@ static void ice_gnss_read(struct kthread_work *work) dev_warn(ice_pf_to_dev(pf), "gnss_insert_raw ret=%d size=%d\n", count, i); -exit_buf: + delay = ICE_GNSS_TIMER_DELAY_TIME; +free_buf: free_page((unsigned long)buf); - kthread_queue_delayed_work(gnss->kworker, &gnss->read_work, - ICE_GNSS_TIMER_DELAY_TIME); +requeue: + kthread_queue_delayed_work(gnss->kworker, &gnss->read_work, delay); exit: if (err) dev_dbg(ice_pf_to_dev(pf), "GNSS failed to read err=%d\n", err); -- cgit v1.2.3