From aa659a3fca79abd9a3ca3ddc535db631b01c9a02 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Fri, 13 Dec 2019 09:55:33 +0100 Subject: [PATCH] ACPI: processor: Clean up acpi_processor_evaluate_cst() Clean up acpi_processor_evaluate_cst() in multiple ways: * Rename current_count to last_index which matches the purpose of the variable better. * Consistently use acpi_handle_*() for printing messages and make the messages cleaner. * Drop redundant parens and braces. * Rewrite and clarify comments. * Rearrange checks and drop the redundant ones. No intentional functional impact. Signed-off-by: Rafael J. Wysocki --- drivers/acpi/processor_idle.c | 114 ++++++++++++++++------------------ 1 file changed, 52 insertions(+), 62 deletions(-) diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index e92d0e6d4cd1..7c2fe3b2ec31 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -304,29 +304,29 @@ static int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu, union acpi_object *cst; acpi_status status; u64 count; - int current_count = 0; + int last_index = 0; int i, ret = 0; status = acpi_evaluate_object(handle, "_CST", NULL, &buffer); if (ACPI_FAILURE(status)) { - ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No _CST, giving up\n")); + acpi_handle_debug(handle, "No _CST\n"); return -ENODEV; } cst = buffer.pointer; - /* There must be at least 2 elements */ - if (!cst || (cst->type != ACPI_TYPE_PACKAGE) || cst->package.count < 2) { - pr_err("not enough elements in _CST\n"); + /* There must be at least 2 elements. */ + if (!cst || cst->type != ACPI_TYPE_PACKAGE || cst->package.count < 2) { + acpi_handle_warn(handle, "Invalid _CST output\n"); ret = -EFAULT; goto end; } count = cst->package.elements[0].integer.value; - /* Validate number of power states. */ + /* Validate the number of C-states. */ if (count < 1 || count != cst->package.count - 1) { - pr_err("count given by _CST is not valid\n"); + acpi_handle_warn(handle, "Inconsistent _CST data\n"); ret = -EFAULT; goto end; } @@ -337,111 +337,101 @@ static int acpi_processor_evaluate_cst(acpi_handle handle, u32 cpu, struct acpi_power_register *reg; struct acpi_processor_cx cx; + /* + * If there is not enough space for all C-states, skip the + * excess ones and log a warning. + */ + if (last_index >= ACPI_PROCESSOR_MAX_POWER - 1) { + acpi_handle_warn(handle, + "No room for more idle states (limit: %d)\n", + ACPI_PROCESSOR_MAX_POWER - 1); + break; + } + memset(&cx, 0, sizeof(cx)); - element = &(cst->package.elements[i]); + element = &cst->package.elements[i]; if (element->type != ACPI_TYPE_PACKAGE) continue; if (element->package.count != 4) continue; - obj = &(element->package.elements[0]); + obj = &element->package.elements[0]; if (obj->type != ACPI_TYPE_BUFFER) continue; reg = (struct acpi_power_register *)obj->buffer.pointer; - if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO && - (reg->space_id != ACPI_ADR_SPACE_FIXED_HARDWARE)) - continue; - - /* There should be an easy way to extract an integer... */ - obj = &(element->package.elements[1]); + obj = &element->package.elements[1]; if (obj->type != ACPI_TYPE_INTEGER) continue; cx.type = obj->integer.value; /* - * Some buggy BIOSes won't list C1 in _CST - - * Let acpi_processor_get_power_info_default() handle them later + * There are known cases in which the _CST output does not + * contain C1, so if the type of the first state found is not + * C1, leave an empty slot for C1 to be filled in later. */ if (i == 1 && cx.type != ACPI_STATE_C1) - current_count++; + last_index = 1; cx.address = reg->address; - cx.index = current_count + 1; + cx.index = last_index + 1; - cx.entry_method = ACPI_CSTATE_SYSTEMIO; if (reg->space_id == ACPI_ADR_SPACE_FIXED_HARDWARE) { - if (acpi_processor_ffh_cstate_probe - (cpu, &cx, reg) == 0) { - cx.entry_method = ACPI_CSTATE_FFH; + if (!acpi_processor_ffh_cstate_probe(cpu, &cx, reg)) { + /* + * In the majority of cases _CST describes C1 as + * a FIXED_HARDWARE C-state, but if the command + * line forbids using MWAIT, use CSTATE_HALT for + * C1 regardless. + */ + if (cx.type == ACPI_STATE_C1 && + boot_option_idle_override == IDLE_NOMWAIT) { + cx.entry_method = ACPI_CSTATE_HALT; + snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT"); + } else { + cx.entry_method = ACPI_CSTATE_FFH; + } } else if (cx.type == ACPI_STATE_C1) { /* - * C1 is a special case where FIXED_HARDWARE - * can be handled in non-MWAIT way as well. - * In that case, save this _CST entry info. - * Otherwise, ignore this info and continue. + * In the special case of C1, FIXED_HARDWARE can + * be handled by executing the HLT instruction. */ cx.entry_method = ACPI_CSTATE_HALT; snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT"); } else { continue; } - if (cx.type == ACPI_STATE_C1 && - (boot_option_idle_override == IDLE_NOMWAIT)) { - /* - * In most cases the C1 space_id obtained from - * _CST object is FIXED_HARDWARE access mode. - * But when the option of idle=halt is added, - * the entry_method type should be changed from - * CSTATE_FFH to CSTATE_HALT. - * When the option of idle=nomwait is added, - * the C1 entry_method type should be - * CSTATE_HALT. - */ - cx.entry_method = ACPI_CSTATE_HALT; - snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI HLT"); - } - } else { + } else if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_IO) { + cx.entry_method = ACPI_CSTATE_SYSTEMIO; snprintf(cx.desc, ACPI_CX_DESC_LEN, "ACPI IOPORT 0x%x", cx.address); + } else { + continue; } - if (cx.type == ACPI_STATE_C1) { + if (cx.type == ACPI_STATE_C1) cx.valid = 1; - } - obj = &(element->package.elements[2]); + obj = &element->package.elements[2]; if (obj->type != ACPI_TYPE_INTEGER) continue; cx.latency = obj->integer.value; - obj = &(element->package.elements[3]); + obj = &element->package.elements[3]; if (obj->type != ACPI_TYPE_INTEGER) continue; - current_count++; - memcpy(&info->states[current_count], &cx, sizeof(cx)); - - /* - * We support total ACPI_PROCESSOR_MAX_POWER - 1 - * (From 1 through ACPI_PROCESSOR_MAX_POWER - 1) - */ - if (current_count >= (ACPI_PROCESSOR_MAX_POWER - 1)) { - pr_warn("Limiting number of power states to max (%d)\n", - ACPI_PROCESSOR_MAX_POWER); - pr_warn("Please increase ACPI_PROCESSOR_MAX_POWER if needed.\n"); - break; - } + memcpy(&info->states[++last_index], &cx, sizeof(cx)); } - acpi_handle_info(handle, "Found %d idle states\n", current_count); + acpi_handle_info(handle, "Found %d idle states\n", last_index); - info->count = current_count; + info->count = last_index; end: kfree(buffer.pointer);