Re: Allow setting a power cap that's lower than recommended

[Mario Limonciello]

On 5/3/2024 07:05, fililip wrote:

This patch allows setting a low power cap if |ignore_min_pcap|​ is set to 1.

Signed-off-by: fililip 


Rather than an attachment you should send the patch inline.  That would 
mean that your commit message and SoB should be at the top of the patch 
itself.


If you're not aware of it, you should read through:

https://www.kernel.org/doc/html/latest/process/submitting-patches.html

Basically a maintainer should be able to run:

'b4 shazam $URL'

And it would download the patch and apply it.

That being said my comments on the patch content:

As Alex mentioned a concern about the the maintenance of more 
parameters, maybe it's worth making the sysfs file of the limit 
"writable" instead.


Then when it's written the kernel driver can add_taint() for 
TAINT_FIRMWARE_WORKAROUND when in use so we can see it clearly in logs.

Re: Allow setting a power cap that's lower than recommended

[Alex Deucher]

On Fri, May 3, 2024 at 9:27 AM fililip  wrote:
>
> This patch allows setting a low power cap if ignore_min_pcap is set to 1.
>
> Signed-off-by: fililip 

Please generate a proper signed off git patch and use git-send-email
to send it out.  Also, I don't want to add more module parameters.

Alex

Allow setting a power cap that's lower than recommended

[fililip]

This patch allows setting a low power cap if ignore_min_pcap​ is set to 1.

Signed-off-by: fililip diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 50f57d4dfd8f..b83697b75221 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -151,6 +151,7 @@ struct amdgpu_watchdog_timer
  */
 extern int amdgpu_modeset;
 extern unsigned int amdgpu_vram_limit;
+extern int amdgpu_ignore_min_pcap;
 extern int amdgpu_vis_vram_limit;
 extern int amdgpu_gart_size;
 extern int amdgpu_gtt_size;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index a7ad77ed09ca..2b7ed2e48e33 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -131,6 +131,7 @@ enum AMDGPU_DEBUG_MASK {
 };
 
 unsigned int amdgpu_vram_limit = UINT_MAX;
+int amdgpu_ignore_min_pcap = 0; /* do not ignore by default */
 int amdgpu_vis_vram_limit;
 int amdgpu_gart_size = -1; /* auto */
 int amdgpu_gtt_size = -1; /* auto */
@@ -238,6 +239,15 @@ struct amdgpu_watchdog_timer amdgpu_watchdog_timer = {
 	.period = 0x0, /* default to 0x0 (timeout disable) */
 };
 
+/**
+ * DOC: ignore_min_pcap (int)
+ * Ignore the minimum power cap.
+ * Useful on graphics cards where the minimum power cap is very high.
+ * The default is 0 (Do not ignore).
+ */
+MODULE_PARM_DESC(ignore_min_pcap, "Ignore the minimum power cap");
+module_param_named(ignore_min_pcap, amdgpu_ignore_min_pcap, int, 0600);
+
 /**
  * DOC: vramlimit (int)
  * Restrict the total amount of VRAM in MiB for testing.  The default is 0 (Use full VRAM).
diff --git a/drivers/gpu/drm/amd/pm/amdgpu_pm.c b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
index 20c53eefd680..6d00cae9caec 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_pm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_pm.c
@@ -2984,6 +2984,9 @@ static ssize_t amdgpu_hwmon_show_power_cap_min(struct device *dev,
 	 struct device_attribute *attr,
 	 char *buf)
 {
+	if (amdgpu_ignore_min_pcap)
+		return sysfs_emit(buf, "%i\n", 0);
+
 	return amdgpu_hwmon_show_power_cap_generic(dev, attr, buf, PP_PWR_LIMIT_MIN);
 }
 
diff --git a/drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c b/drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c
index 60dce148b2d7..72891811b2d5 100644
--- a/drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c
+++ b/drivers/gpu/drm/amd/pm/swsmu/amdgpu_smu.c
@@ -2487,7 +2487,10 @@ int smu_get_power_limit(void *handle,
 			*limit = smu->max_power_limit;
 			break;
 		case SMU_PPT_LIMIT_MIN:
-			*limit = smu->min_power_limit;
+			if (amdgpu_ignore_min_pcap)
+*limit = 0;
+			else
+*limit = smu->min_power_limit;
 			break;
 		default:
 			return -EINVAL;
@@ -2511,7 +2514,14 @@ static int smu_set_power_limit(void *handle, uint32_t limit)
 		if (smu->ppt_funcs->set_power_limit)
 			return smu->ppt_funcs->set_power_limit(smu, limit_type, limit);
 
-	if ((limit > smu->max_power_limit) || (limit < smu->min_power_limit)) {
+	if (amdgpu_ignore_min_pcap) {
+		if ((limit > smu->max_power_limit)) {
+			dev_err(smu->adev->dev,
+"New power limit (%d) is over the max allowed %d\n",
+limit, smu->max_power_limit);
+			return -EINVAL;
+		}
+	} else if ((limit > smu->max_power_limit) || (limit < smu->min_power_limit)) {
 		dev_err(smu->adev->dev,
 			"New power limit (%d) is out of range [%d,%d]\n",
 			limit, smu->min_power_limit, smu->max_power_limit);