Re: [PATCH v2] drm/amdgpu: fix that issue that the number of the crtc of the 3250c is not correct

From: Paul Menzel <pmenzel@molgen.mpg.de>
To: Ryan Lin <tsung-hua.lin@amd.com>
Cc: "Chun Ming Zhou" <David1.Zhou@amd.com>,
	"Drew Davenport" <ddavenport@chromium.org>,
	"Leo Li" <sunpeng.li@amd.com>,
	leon.li@amd.com, dri-devel@lists.freedesktop.org,
	"Rodrigo Siqueira" <Rodrigo.Siqueira@amd.com>,
	linux-kernel@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	"Christian König" <christian.koenig@amd.com>,
	"David Airlie" <airlied@linux.ie>,
	"Sean Paul" <seanpaul@chromium.org>,
	"Louis Li" <ching-shih.li@amd.corp-partner.google.com>,
	"Daniel Vetter" <daniel@ffwll.ch>,
	"Bas Nieuwenhuizen" <bas@basnieuwenhuizen.nl>,
	"Alex Deucher" <alexander.deucher@amd.com>,
	"Stéphane Marchesin" <marcheu@chromium.org>,
	"Nicholas Kazlauskas" <nicholas.kazlauskas@amd.com>,
	"Harry Wentland" <harry.wentland@amd.com>,
	"Mark Yacoub" <markyacoub@google.com>
Subject: Re: [PATCH v2] drm/amdgpu: fix that issue that the number of the crtc of the 3250c is not correct
Date: Wed, 30 Mar 2022 08:34:02 +0200	[thread overview]
Message-ID: <de559e34-3b56-a3d5-cd7a-89bc8f5528d7@molgen.mpg.de> (raw)
In-Reply-To: <20220330024643.162230-1-tsung-hua.lin@amd.com>

Dear Tsung-Hua,

Thank you for your patch.

Am 30.03.22 um 04:46 schrieb Ryan Lin:

The commit message summary is quite long and confusing. Maybe:

Use 3 CRTC for 3250c to get internal display working

> [Why]
> External displays take priority over internal display when there are fewer
> display controllers than displays.

This causes the internal display to not work on the Chromebook google/zork.

> [How]
> The root cause is because of that number of the crtc is not correct.

The root cause is the incorrect number of four configured CRTCs.

> The number of the crtc on the 3250c is 3, but on the 3500c is 4.
> On the source code, we can see that number of the crtc has been fixed at 4.
> Needs to set the num_crtc to 3 for 3250c platform.

Please do not wrap lines after each sentence, and use a text width of 75 
characters.

> v2:
>     - remove unnecessary comments and Id
> 
> Signed-off-by: Ryan Lin <tsung-hua.lin@amd.com>
> 
> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 12 +++++++++---
>   1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 40c91b448f7da..455a2c45e8cda 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -2738,9 +2738,15 @@ static int dm_early_init(void *handle)
>   		break;
>   #if defined(CONFIG_DRM_AMD_DC_DCN1_0)
>   	case CHIP_RAVEN:
> -		adev->mode_info.num_crtc = 4;
> -		adev->mode_info.num_hpd = 4;
> -		adev->mode_info.num_dig = 4;
> +		if (adev->rev_id >= 8) {

Is there some define for that number? Maybe add a comment, that it’s for 
3250c?

Kind regards,

Paul

> +			adev->mode_info.num_crtc = 3;
> +			adev->mode_info.num_hpd = 3;
> +			adev->mode_info.num_dig = 3;
> +		} else {
> +			adev->mode_info.num_crtc = 4;
> +			adev->mode_info.num_hpd = 4;
> +			adev->mode_info.num_dig = 4;
> +		}
>   		break;
>   #endif
>   #if defined(CONFIG_DRM_AMD_DC_DCN2_0)