[PATCH] drm/amdgpu: no DC support for headless chips

[Alex Deucher]

On Thu, Dec 23, 2021 at 9:54 PM Chen, Guchun <Guchun.Chen at amd.com> wrote:
>
> [Public]
>
> For the first two CHIP_HAINAN and CHIP_TOPAZ, using asic_type is fine. But for CHIP_ARCTURUS and CHIP_ALDEBARAN, I wonder if there is any dc hardware harvesting info carried by harvest table in VBIOS. If that's the case, I think we can drop these two, as we can promise it by checking AMD_HARVEST_IP_DMU_MASK in amdgpu_device_has_dc_support.

There is no IP discovery table for these chips, but they don't have
any display IPs in the hardcoded IP discovery info in the driver.  I
don't think this should affect them, but I wasn't sure..

Alex


>
> Regards,
> Guchun
>
> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Alex Deucher
> Sent: Friday, December 24, 2021 3:20 AM
> To: amd-gfx at lists.freedesktop.org
> Cc: Deucher, Alexander <Alexander.Deucher at amd.com>; tarequemd.hanif at yahoo.com
> Subject: [PATCH] drm/amdgpu: no DC support for headless chips
>
> Chips with no display hardware should return false for DC support.
>
> Fixes: f7f12b25823c0d ("drm/amdgpu: default to true in amdgpu_device_asic_has_dc_support")
> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 9dc86c5a1cad..58e2034984de 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -3166,6 +3166,14 @@ static void amdgpu_device_detect_sriov_bios(struct amdgpu_device *adev)  bool amdgpu_device_asic_has_dc_support(enum amd_asic_type asic_type)  {
>         switch (asic_type) {
> +#ifdef CONFIG_DRM_AMDGPU_SI
> +       case CHIP_HAINAN:
> +#endif
> +       case CHIP_TOPAZ:
> +       case CHIP_ARCTURUS:
> +       case CHIP_ALDEBARAN:
> +               /* chips with no display hardware */
> +               return false;
>  #if defined(CONFIG_DRM_AMD_DC)
>         case CHIP_TAHITI:
>         case CHIP_PITCAIRN:
> --
> 2.33.1