From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7E1622D6630; Thu, 4 Sep 2025 18:37:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757011021; cv=none; b=jW5uednLDTDFrpp328hYJsD3FYWK37zCXESbnRS0NpDl2+2enbP2UV1ZVzDtY7zITvQD7HWb68UrC4BMYAghw2c+TDbpFNrO9O1k8Tweibc4DwkVj/09Ju0N8+u+bbkxI16jcwwDqE9v7fu2Jd2iDTqFQCoWnSRs0F/mLZyOoWs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757011021; c=relaxed/simple; bh=ftjP0BgBhol/aJqy+0EAcs43kMLIGJAJVDQe4elAqE4=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=h0ACGuTdABIgH0uFNJcnfgrKPGvV3NyvZRMb1PWCXYHBluFNGn44hpWzAHncvatmxbR+USsvsvBlYl/a7rncQ6br+xqYzyMkp4g34Q3P2C5YJ1EgSOEas06uQsmjD+g4S/j7WpOI8bhAiZB4W9ngmM42GBsZ5bn+qq+dUodOx1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=fK9TtnAK; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="fK9TtnAK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CBB9FC4CEF0; Thu, 4 Sep 2025 18:37:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757011021; bh=ftjP0BgBhol/aJqy+0EAcs43kMLIGJAJVDQe4elAqE4=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=fK9TtnAKgXX/kekyaKxa6YXvorPUEg6avFCJKW5o6hy8TneIFexM7MlDX4I167iE3 EwO9anL4coTCc35WrDYsxvkW4xgN5a5ivg89pJUyIySyWFa9wi0bOTYCknilvZtMWT 8hjAzcy9qigvBk6oo2MNBYxfOGHKrv/2gK7BjRuL64TMZePW2DN72v8JMTED5g0KMi z1AJHjUwEiMGdTrlnis2laZaZzD58lgLmtgLjgnVy0HTpl07f9o+9yCjA7NSH+QZya 4oP2mYzZxuGn9s8W9f/Qkw7FdkwKY26cWuuNAEv5WSDDoQW6iE/WQWc5H1/+NikuVn EBV7fea9xR9nA== Date: Thu, 4 Sep 2025 13:36:59 -0500 From: Bjorn Helgaas To: Badal Nilawar Cc: intel-xe@lists.freedesktop.org, linux-acpi@vger.kernel.org, linux-pci@vger.kernel.org, anshuman.gupta@intel.com, rafael@kernel.org, lenb@kernel.org, bhelgaas@google.com, ilpo.jarvinen@linux.intel.com, lucas.demarchi@intel.com, rodrigo.vivi@intel.com, varun.gupta@intel.com, ville.syrjala@linux.intel.com, uma.shankar@intel.com Subject: Re: [PATCH v4 02/11] PCI/ACPI: Per root port allow one Aux power limit request Message-ID: <20250904183659.GA1271032@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250529111654.3140766-3-badal.nilawar@intel.com> On Thu, May 29, 2025 at 04:46:45PM +0530, Badal Nilawar wrote: > For given root port allow one Aux power limit request. Please include the reason why we do this. I don't think we need it. PCI Firmware r3.3, sec 4.6.10 says this _DSM function can be invoked multiple times with different requests. We might need a mutex just to avoid concurrent evaluations of this _DSM function by different drivers; I'm not sure whether there's a requirement to avoid that or whether the ACPI core already enforces something like that. But that would be a separate thing from aux_power_limit. > Cc: Rafael J. Wysocki > Cc: Anshuman Gupta > Signed-off-by: Badal Nilawar > --- > drivers/acpi/scan.c | 1 + > drivers/pci/pci-acpi.c | 25 ++++++++++++++++++++++++- > include/acpi/acpi_bus.h | 2 ++ > 3 files changed, 27 insertions(+), 1 deletion(-) > > diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c > index fb1fe9f3b1a3..9ae7be9db01a 100644 > --- a/drivers/acpi/scan.c > +++ b/drivers/acpi/scan.c > @@ -745,6 +745,7 @@ int acpi_device_add(struct acpi_device *device) > INIT_LIST_HEAD(&device->physical_node_list); > INIT_LIST_HEAD(&device->del_list); > mutex_init(&device->physical_node_lock); > + mutex_init(&device->power.aux_pwr_lock); > > mutex_lock(&acpi_device_lock); > > diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c > index 87f30910a5f1..d33efba4ca94 100644 > --- a/drivers/pci/pci-acpi.c > +++ b/drivers/pci/pci-acpi.c > @@ -1451,6 +1451,7 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power, > union acpi_object *out_obj; > acpi_handle handle; > int result, ret = -EINVAL; > + struct acpi_device *adev; > > if (!dev || !retry_interval) > return -EINVAL; > @@ -1464,11 +1465,27 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power, > return -ENODEV; > } > > + adev = ACPI_COMPANION(&dev->dev); > + if (!adev) > + return -EINVAL; > + > + mutex_lock(&adev->power.aux_pwr_lock); > + > + /* Check if aux power already granted */ > + if (adev->power.aux_power_limit) { > + pci_info(dev, "D3cold Aux Power request already granted: %u mW\n", > + adev->power.aux_power_limit); > + mutex_unlock(&adev->power.aux_pwr_lock); > + return -EPERM; > + } > + > out_obj = acpi_evaluate_dsm_typed(handle, &pci_acpi_dsm_guid, 4, > DSM_PCI_D3COLD_AUX_POWER_LIMIT, > &in_obj, ACPI_TYPE_INTEGER); > - if (!out_obj) > + if (!out_obj) { > + mutex_unlock(&adev->power.aux_pwr_lock); > return -EINVAL; > + } > > result = out_obj->integer.value; > if (retry_interval) > @@ -1478,14 +1495,17 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power, > case 0x0: > pci_dbg(dev, "D3cold Aux Power %u mW request denied\n", > requested_power); > + adev->power.aux_power_limit = 0; > break; > case 0x1: > pci_info(dev, "D3cold Aux Power request granted: %u mW\n", > requested_power); > + adev->power.aux_power_limit = requested_power; > ret = 0; > break; > case 0x2: > pci_info(dev, "D3cold Aux Power: Main power won't be removed\n"); > + adev->power.aux_power_limit = 0; > ret = -EBUSY; > break; > default: > @@ -1500,9 +1520,12 @@ int pci_acpi_request_d3cold_aux_power(struct pci_dev *dev, u32 requested_power, > pci_err(dev, "D3cold Aux Power: Reserved or unsupported response: 0x%x\n", > result); > } > + adev->power.aux_power_limit = 0; > break; > } > > + mutex_unlock(&adev->power.aux_pwr_lock); > + > ACPI_FREE(out_obj); > return ret; > } > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index aad1a95e6863..c4ce3d84be00 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -294,6 +294,8 @@ struct acpi_device_power { > struct acpi_device_power_flags flags; > struct acpi_device_power_state states[ACPI_D_STATE_COUNT]; /* Power states (D0-D3Cold) */ > u8 state_for_enumeration; /* Deepest power state for enumeration */ > + u32 aux_power_limit; /* aux power limit granted by bios */ > + struct mutex aux_pwr_lock; /* prevent concurrent aux power limit requests */ > }; > > struct acpi_dep_data { > -- > 2.34.1 >