On Wed, May 11, 2022 at 2:20 PM Lyude Paul <[email protected]> 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.
>
> 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 <[email protected]>
> ---
> 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
>
Am 11.05.22 um 20:36 schrieb Alex Deucher:
> On Wed, May 11, 2022 at 2:20 PM Lyude Paul <[email protected]> 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 <[email protected]>
>> ---
>> 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
>>