From e24328974a88aa8541e94e8bb8dfa2ade1b3c45d Mon Sep 17 00:00:00 2001 From: Donggeun Yoo Date: Wed, 2 Sep 2026 00:21:26 +0900 Subject: iio: proximity: vl53l0x-i2c: claim direct mode for raw reads vl53l0x_read_raw() starts a single-shot ranging measurement and reads back the result. Once the triggered buffer is enabled the sensor runs in continuous mode and its data-ready interrupt is routed to the trigger, so a concurrent in_distance_raw read disturbs the streaming setup and never gets its completion, returning -ETIMEDOUT. The original submission claimed direct mode here, but it was dropped during review because the driver had no buffer support at the time [1]. Continuous (buffered) mode was later added without restoring the claim [2], reintroducing the conflict. Reject direct reads while buffered capture is active by claiming direct mode around the measurement, as the vl53l1x sibling already does. Fixes: 762186c6e7b1 ("iio: proximity: vl53l0x-i2c: Added continuous mode support") Link: https://lore.kernel.org/linux-iio/20180911160300.GA9212@himanshu-Vostro-3559/ [1] Link: https://lore.kernel.org/linux-iio/20240909101508.263085-3-abhashkumarjha123@gmail.com/ [2] Signed-off-by: Donggeun Yoo Cc: stable@vger.kernel.org Signed-off-by: Jonathan Cameron --- include/clocksource/hyperv_timer.h | 111 +++++++++++++++++++++++++++++++++++++ 1 file changed, 111 insertions(+) create mode 100644 include/clocksource/hyperv_timer.h (limited to 'include/clocksource/hyperv_timer.h') diff --git a/include/clocksource/hyperv_timer.h b/include/clocksource/hyperv_timer.h new file mode 100644 index 000000000..8d3befb7e --- /dev/null +++ b/include/clocksource/hyperv_timer.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0 */ + +/* + * Definitions for the clocksource provided by the Hyper-V + * hypervisor to guest VMs, as described in the Hyper-V Top + * Level Functional Spec (TLFS). + * + * Copyright (C) 2019, Microsoft, Inc. + * + * Author: Michael Kelley + */ + +#ifndef __CLKSOURCE_HYPERV_TIMER_H +#define __CLKSOURCE_HYPERV_TIMER_H + +#include +#include +#include + +#define HV_MAX_MAX_DELTA_TICKS 0xffffffff +#define HV_MIN_DELTA_TICKS 1 + +#ifdef CONFIG_HYPERV_TIMER + +#include + +/* Routines called by the VMbus driver */ +extern int hv_stimer_alloc(bool have_percpu_irqs); +extern int hv_stimer_cleanup(unsigned int cpu); +extern void hv_stimer_global_cleanup(void); + +extern void hv_init_clocksource(void); +extern void hv_remap_tsc_clocksource(void); + +extern unsigned long hv_get_tsc_pfn(void); +extern struct ms_hyperv_tsc_page *hv_get_tsc_page(void); + +extern void hv_adj_sched_clock_offset(u64 offset); + +static __always_inline bool +hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, + u64 *cur_tsc, u64 *time) +{ + u64 scale, offset; + u32 sequence; + + /* + * The protocol for reading Hyper-V TSC page is specified in Hypervisor + * Top-Level Functional Specification ver. 3.0 and above. To get the + * reference time we must do the following: + * - READ ReferenceTscSequence + * A special '0' value indicates the time source is unreliable and we + * need to use something else. The currently published specification + * versions (up to 4.0b) contain a mistake and wrongly claim '-1' + * instead of '0' as the special value, see commit c35b82ef0294. + * - ReferenceTime = + * ((RDTSC() * ReferenceTscScale) >> 64) + ReferenceTscOffset + * - READ ReferenceTscSequence again. In case its value has changed + * since our first reading we need to discard ReferenceTime and repeat + * the whole sequence as the hypervisor was updating the page in + * between. + */ + do { + sequence = READ_ONCE(tsc_pg->tsc_sequence); + if (!sequence) + return false; + /* + * Make sure we read sequence before we read other values from + * TSC page. + */ + smp_rmb(); + + scale = READ_ONCE(tsc_pg->tsc_scale); + offset = READ_ONCE(tsc_pg->tsc_offset); + *cur_tsc = hv_get_raw_timer(); + + /* + * Make sure we read sequence after we read all other values + * from TSC page. + */ + smp_rmb(); + + } while (READ_ONCE(tsc_pg->tsc_sequence) != sequence); + + *time = mul_u64_u64_shr(*cur_tsc, scale, 64) + offset; + return true; +} + +#else /* CONFIG_HYPERV_TIMER */ +static inline unsigned long hv_get_tsc_pfn(void) +{ + return 0; +} + +static inline struct ms_hyperv_tsc_page *hv_get_tsc_page(void) +{ + return NULL; +} + +static __always_inline bool +hv_read_tsc_page_tsc(const struct ms_hyperv_tsc_page *tsc_pg, u64 *cur_tsc, u64 *time) +{ + return false; +} + +static inline int hv_stimer_cleanup(unsigned int cpu) { return 0; } +static inline void hv_stimer_global_cleanup(void) {} + +#endif /* CONFIG_HYPERV_TIMER */ + +#endif -- cgit v1.3.1