linux-kernel - Re: [PATCH] drm/amd/amdgpu: Add modeset module parameter support

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Date:   Mon, 29 Aug 2022 09:47:50 -0400
From:   Alex Deucher <alexdeucher@...il.com>
To:     Zhen Ni <nizhen@...ontech.com>
Cc:     airlied@...ux.ie, daniel@...ll.ch, evan.quan@....com,
        dri-devel@...ts.freedesktop.org, amd-gfx@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/amd/amdgpu: Add modeset module parameter support

On Mon, Aug 29, 2022 at 9:43 AM Zhen Ni <nizhen@...ontech.com> wrote:
>
> Nomodeset kernel parameter is for all graphics cards. Amdgpu cannot
> be set separately in some scenarios, such as hybrid graphics(i + a).
> Add modeset module parameter for amdgpu to set kernel mode separately.
>
> Signed-off-by: Zhen Ni <nizhen@...ontech.com>

amdgpu didn't support this option since it never supported the legacy
drm mode that other older drivers did.  If you just want the option to
keep the driver from loading, you can already do this by blacklisting
the driver.  E.g.,
modprobe.blacklist=amdgpu

Alex

> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> index 429fcdf28836..856a70370e3c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> @@ -107,6 +107,7 @@
>  #define KMS_DRIVER_MINOR       48
>  #define KMS_DRIVER_PATCHLEVEL  0
>
> +int amdgpu_modeset = -1;
>  int amdgpu_vram_limit;
>  int amdgpu_vis_vram_limit;
>  int amdgpu_gart_size = -1; /* auto */
> @@ -199,6 +200,13 @@ struct amdgpu_watchdog_timer amdgpu_watchdog_timer = {
>         .period = 0x0, /* default to 0x0 (timeout disable) */
>  };
>
> +/**
> + * DOC: modeset (int)
> + * Disable/Enable kernel modesetting (1 = enable, 0 = disable, -1 = auto (default)).
> + */
> +MODULE_PARM_DESC(modeset, "Disable/Enable kernel modesetting");
> +module_param_named(modeset, amdgpu_modeset, int, 0400);
> +
>  /**
>   * DOC: vramlimit (int)
>   * Restrict the total amount of VRAM in MiB for testing.  The default is 0 (Use full VRAM).
> @@ -2753,7 +2761,10 @@ static int __init amdgpu_init(void)
>  {
>         int r;
>
> -       if (drm_firmware_drivers_only())
> +       if (drm_firmware_drivers_only() && amdgpu_modeset == -1)
> +               amdgpu_modeset = 0;
> +
> +       if (amdgpu_modeset == 0)
>                 return -EINVAL;
>
>         r = amdgpu_sync_init();
> --
> 2.20.1
>