From mboxrd@z Thu Jan 1 00:00:00 1970 From: Prashanth Prakash Subject: [PATCH V3 2/7] ACPI/CPPC: acquire pcc_lock only while accessing PCC subspace Date: Tue, 16 Aug 2016 14:39:39 -0600 Message-ID: <1471379984-15712-3-git-send-email-pprakash@codeaurora.org> References: <1471379984-15712-1-git-send-email-pprakash@codeaurora.org> Return-path: Received: from smtp.codeaurora.org ([198.145.29.96]:54893 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752425AbcHPUj4 (ORCPT ); Tue, 16 Aug 2016 16:39:56 -0400 In-Reply-To: <1471379984-15712-1-git-send-email-pprakash@codeaurora.org> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: linux-acpi@vger.kernel.org Cc: rjw@rjwysocki.net, alexey.klimov@arm.com, hotran@apm.com, cov@codeaurora.org, Prashanth Prakash We need to acquire pcc_lock only when we are accessing registers that are in the PCC subspsace. Cc: "Rafael J. Wysocki" Signed-off-by: Prashanth Prakash --- drivers/acpi/cppc_acpi.c | 30 ++++++++++++++++-------------- 1 file changed, 16 insertions(+), 14 deletions(-) diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index fea58e2..93826c7 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -763,7 +763,7 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) struct cpc_register_resource *highest_reg, *lowest_reg, *ref_perf, *nom_perf; u64 high, low, ref, nom; - int ret = 0; + int ret = 0, regs_in_pcc = 0; if (!cpc_desc) { pr_debug("No CPC descriptor for CPU:%d\n", cpunum); @@ -775,13 +775,13 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) ref_perf = &cpc_desc->cpc_regs[REFERENCE_PERF]; nom_perf = &cpc_desc->cpc_regs[NOMINAL_PERF]; - spin_lock(&pcc_lock); - /* Are any of the regs PCC ?*/ if ((highest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || - (lowest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || - (ref_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || - (nom_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) { + (lowest_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || + (ref_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || + (nom_perf->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) { + spin_lock(&pcc_lock); + regs_in_pcc = 1; /* Ring doorbell once to update PCC subspace */ if (send_pcc_cmd(CMD_READ) < 0) { ret = -EIO; @@ -808,7 +808,8 @@ int cppc_get_perf_caps(int cpunum, struct cppc_perf_caps *perf_caps) ret = -EFAULT; out_err: - spin_unlock(&pcc_lock); + if (regs_in_pcc) + spin_unlock(&pcc_lock); return ret; } EXPORT_SYMBOL_GPL(cppc_get_perf_caps); @@ -825,7 +826,7 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpunum); struct cpc_register_resource *delivered_reg, *reference_reg; u64 delivered, reference; - int ret = 0; + int ret = 0, regs_in_pcc = 0; if (!cpc_desc) { pr_debug("No CPC descriptor for CPU:%d\n", cpunum); @@ -835,11 +836,11 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) delivered_reg = &cpc_desc->cpc_regs[DELIVERED_CTR]; reference_reg = &cpc_desc->cpc_regs[REFERENCE_CTR]; - spin_lock(&pcc_lock); - /* Are any of the regs PCC ?*/ if ((delivered_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) || (reference_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM)) { + spin_lock(&pcc_lock); + regs_in_pcc = 1; /* Ring doorbell once to update PCC subspace */ if (send_pcc_cmd(CMD_READ) < 0) { ret = -EIO; @@ -865,7 +866,8 @@ int cppc_get_perf_ctrs(int cpunum, struct cppc_perf_fb_ctrs *perf_fb_ctrs) perf_fb_ctrs->prev_reference = reference; out_err: - spin_unlock(&pcc_lock); + if (regs_in_pcc) + spin_unlock(&pcc_lock); return ret; } EXPORT_SYMBOL_GPL(cppc_get_perf_ctrs); @@ -890,10 +892,9 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF]; - spin_lock(&pcc_lock); - /* If this is PCC reg, check if channel is free before writing */ if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) { + spin_lock(&pcc_lock); ret = check_pcc_chan(); if (ret) goto busy_channel; @@ -912,7 +913,8 @@ int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls) ret = -EIO; } busy_channel: - spin_unlock(&pcc_lock); + if (desired_reg->cpc_entry.reg.space_id == ACPI_ADR_SPACE_PLATFORM_COMM) + spin_unlock(&pcc_lock); return ret; } EXPORT_SYMBOL_GPL(cppc_set_perf); -- Qualcomm Datacenter Technologies on behalf of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.