Am 11.05.22 um 20:36 schrieb Alex Deucher:
On Wed, May 11, 2022 at 2:20 PM Lyude Paul <lyude@xxxxxxxxxx> wrote:
Many DRM drivers feature a 'modeset' argument, which can be used to
enable/disable the entire driver (as opposed to passing nomodeset to the
kernel, which would disable modesetting globally and make it difficult to
load amdgpu afterwards). Apparently amdgpu is actually missing this
however, so let's add it!
You can already do that by passing modprobe.blacklist=amdgpu on the
kernel command line. I don't think we need another option to do that.
Yeah, this already came up multiple times and so far we have always
rejected it.
Stuffing that into drivers is not a good approach I think. If we want to
prevent some device from exposing it's display functionalities we should
rather push that into the drm layer.
Regards,
Christian.
Keep in mind that this currently just lets one enable or disable amdgpu, I
haven't bothered adding a headless mode like nouveau has - however I'm sure
someone else can add this if needed.
You can do this as well by passing an IP block mask which disables the
display IP, or media IP, etc.
Alex
Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
index ebd37fb19cdb..24e6fb4517cc 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
@@ -872,6 +872,15 @@ MODULE_PARM_DESC(smu_pptable_id,
"specify pptable id to be used (-1 = auto(default) value, 0 = use pptable from vbios, > 0 = soft pptable id)");
module_param_named(smu_pptable_id, amdgpu_smu_pptable_id, int, 0444);
+/**
+ * DOC: modeset (int)
+ * Used to enable/disable modesetting for amdgpu exclusively.
+ */
+bool amdgpu_enable_modeset = true;
+MODULE_PARM_DESC(modeset,
+ "Enable or disable display driver (1 = on (default), 0 = off");
+module_param_named(modeset, amdgpu_enable_modeset, bool, 0444);
+
/* These devices are not supported by amdgpu.
* They are supported by the mach64, r128, radeon drivers
*/
@@ -2003,6 +2012,11 @@ static int amdgpu_pci_probe(struct pci_dev *pdev,
bool is_fw_fb;
resource_size_t base, size;
+ if (!amdgpu_enable_modeset) {
+ DRM_INFO("modeset=0 passed to amdgpu, driver will not be enabled\n");
+ return -ENODEV;
+ }
+
/* skip devices which are owned by radeon */
for (i = 0; i < ARRAY_SIZE(amdgpu_unsupported_pciidlist); i++) {
if (amdgpu_unsupported_pciidlist[i] == pdev->device)
--
2.35.1
