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Message-ID: <CADnq5_Mjo7M-ndi0mOUZzrvCnz2gUY0wm0a7uGtdLp=_kWLW0Q@mail.gmail.com>
Date: Mon, 17 Nov 2025 14:48:52 -0500
From: Alex Deucher <alexdeucher@...il.com>
To: "Yo-Jung Leo Lin (AMD)" <Leo.Lin@....com>
Cc: Alex Deucher <alexander.deucher@....com>, 
	Christian König <christian.koenig@....com>, 
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, Jonathan Corbet <corbet@....net>, amd-gfx@...ts.freedesktop.org, 
	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
	linux-doc@...r.kernel.org, "Tsao, Anson" <anson.tsao@....com>, 
	"Mario Limonciello (AMD) (kernel.org)" <superm1@...nel.org>
Subject: Re: [PATCH v2 4/5] drm/amdgpu: add UMA allocation interfaces to sysfs

On Fri, Nov 14, 2025 at 3:52 AM Yo-Jung Leo Lin (AMD) <Leo.Lin@....com> wrote:
>
> Add two sysfs files as interfaces to inspect or change UMA carveout
> size. These files are:
>
> - uma_carveout_options: a read-only file listing all the available
>   UMA allocation options and their index.
>
> - uma_carveout: a file that is both readable and writable. On read,
>   it shows the index of the current setting. Writing a valid index
>   into this file allows users to change the UMA carveout size to that
>   option on the next boot.

Would it be cleaner to combine these?  Reading the file would show the
indexed list of options with a * next to the currently selected one
and then writing the index to the file would cause the change to take
effect on the next reboot.

Alex

>
> Co-developed-by: Mario Limonciello (AMD) <superm1@...nel.org>
> Signed-off-by: Mario Limonciello (AMD) <superm1@...nel.org>
> Signed-off-by: Yo-Jung Leo Lin (AMD) <Leo.Lin@....com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 127 +++++++++++++++++++++++++++++++
>  1 file changed, 127 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> index 444ab4102168..b9378f34eb79 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> @@ -30,6 +30,7 @@
>  #include <linux/power_supply.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/suspend.h>
> +#include <linux/device.h>
>  #include <acpi/video.h>
>  #include <acpi/actbl.h>
>
> @@ -1247,6 +1248,125 @@ int amdgpu_acpi_get_mem_info(struct amdgpu_device *adev, int xcc_id,
>         return -ENOENT;
>  }
>
> +static ssize_t uma_carveout_options_show(struct device *dev,
> +                                        struct device_attribute *attr,
> +                                        char *buf)
> +{
> +       struct amdgpu_uma_carveout_info *uma_info = &amdgpu_acpi_priv.atcs.uma_info;
> +       ssize_t size = 0;
> +
> +       if (!uma_info || !uma_info->num_entries)
> +               return -ENODEV;
> +
> +       for (int i = 0; i < uma_info->num_entries; i++) {
> +               size += sysfs_emit_at(buf, size, "%d: %s (%u GB)\n",
> +                                     i,
> +                                     uma_info->entries[i].name,
> +                                     uma_info->entries[i].memory_carved);
> +       }
> +
> +       return size;
> +}
> +static DEVICE_ATTR_RO(uma_carveout_options);
> +
> +static ssize_t uma_carveout_show(struct device *dev,
> +                                struct device_attribute *attr,
> +                                char *buf)
> +{
> +       return sysfs_emit(buf, "%u\n", amdgpu_acpi_priv.atcs.uma_info.uma_option_index);
> +}
> +
> +static ssize_t uma_carveout_store(struct device *dev,
> +                                 struct device_attribute *attr,
> +                                 const char *buf, size_t count)
> +{
> +       struct amdgpu_uma_carveout_info *uma_info = &amdgpu_acpi_priv.atcs.uma_info;
> +       struct drm_device *ddev = dev_get_drvdata(dev);
> +       struct amdgpu_device *adev = drm_to_adev(ddev);
> +       struct amdgpu_uma_carveout_option *opt;
> +       unsigned long val;
> +       uint8_t flags;
> +       int r;
> +
> +       r = kstrtoul(buf, 10, &val);
> +       if (r)
> +               return r;
> +
> +       if (val >= uma_info->num_entries)
> +               return -EINVAL;
> +
> +       opt = &uma_info->entries[val];
> +
> +       if (!(opt->flags & AMDGPU_UMA_FLAG_AUTO) &&
> +           !(opt->flags & AMDGPU_UMA_FLAG_CUSTOM)) {
> +               drm_err_once(ddev, "Option %ul not supported due to lack of Custom/Auto flag", r);
> +               return -EINVAL;
> +       }
> +
> +       flags = opt->flags;
> +       flags &= ~((flags & AMDGPU_UMA_FLAG_AUTO) >> 1);
> +
> +       guard(mutex)(&uma_info->update_lock);
> +
> +       r = amdgpu_acpi_set_uma_allocation_size(adev, val, flags);
> +       if (r)
> +               return r;
> +
> +       uma_info->uma_option_index = val;
> +
> +       return count;
> +}
> +static DEVICE_ATTR_RW(uma_carveout);
> +
> +static struct attribute *amdgpu_uma_attrs[] = {
> +       &dev_attr_uma_carveout.attr,
> +       &dev_attr_uma_carveout_options.attr,
> +       NULL
> +};
> +
> +const struct attribute_group amdgpu_uma_attr_group = {
> +       .attrs = amdgpu_uma_attrs
> +};
> +
> +static int amdgpu_acpi_uma_option_init(struct amdgpu_device *adev)
> +{
> +       struct amdgpu_atcs *atcs = &amdgpu_acpi_priv.atcs;
> +       int rc;
> +
> +       if (!atcs->functions.set_uma_allocation_size)
> +               return -ENODEV;
> +
> +       rc = amdgpu_atomfirmware_get_uma_carveout_info(adev, &atcs->uma_info);
> +       if (rc) {
> +               drm_dbg(adev_to_drm(adev),
> +                       "Failed to parse UMA carveout info from VBIOS: %d\n", rc);
> +               goto out_info;
> +       }
> +
> +       mutex_init(&atcs->uma_info.update_lock);
> +
> +       rc = devm_device_add_group(adev->dev, &amdgpu_uma_attr_group);
> +       if (rc) {
> +               drm_dbg(adev_to_drm(adev), "Failed to add UMA carveout sysfs interfaces %d\n", rc);
> +               goto out_attr;
> +       }
> +
> +       return 0;
> +
> +out_attr:
> +       mutex_destroy(&atcs->uma_info.update_lock);
> +out_info:
> +       return rc;
> +}
> +
> +static void amdgpu_acpi_uma_option_fini(void)
> +{
> +       struct amdgpu_uma_carveout_info *uma_info = &amdgpu_acpi_priv.atcs.uma_info;
> +
> +       mutex_destroy(&uma_info->update_lock);
> +       uma_info->num_entries = 0;
> +}
> +
>  /**
>   * amdgpu_acpi_event - handle notify events
>   *
> @@ -1291,6 +1411,12 @@ static int amdgpu_acpi_event(struct notifier_block *nb,
>  int amdgpu_acpi_init(struct amdgpu_device *adev)
>  {
>         struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
> +       int rc;
> +
> +       rc = amdgpu_acpi_uma_option_init(adev);
> +
> +       if (rc)
> +               drm_dbg(adev_to_drm(adev), "Not creating uma carveout interfaces: %d", rc);
>
>         if (atif->notifications.brightness_change) {
>                 if (adev->dc_enabled) {
> @@ -1343,6 +1469,7 @@ void amdgpu_acpi_get_backlight_caps(struct amdgpu_dm_backlight_caps *caps)
>  void amdgpu_acpi_fini(struct amdgpu_device *adev)
>  {
>         unregister_acpi_notifier(&adev->acpi_nb);
> +       amdgpu_acpi_uma_option_fini();
>  }
>
>  /**
>
> --
> 2.43.0
>

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