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

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Date:   Wed, 30 Mar 2022 05:50:10 +0000
From:   "Lin, Tsung-hua (Ryan)" <Tsung-hua.Lin@....com>
To:     "VURDIGERENATARAJ, CHANDAN" <CHANDAN.VURDIGERENATARAJ@....com>
CC:     Drew Davenport <ddavenport@...omium.org>,
        "Li, Sun peng (Leo)" <Sunpeng.Li@....com>,
        "Li, Leon" <Leon.Li@....com>,
        "dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
        "Siqueira, Rodrigo" <Rodrigo.Siqueira@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "amd-gfx@...ts.freedesktop.org" <amd-gfx@...ts.freedesktop.org>,
        "Koenig, Christian" <Christian.Koenig@....com>,
        David Airlie <airlied@...ux.ie>,
        Sean Paul <seanpaul@...omium.org>,
        Louis Li <ching-shih.li@....corp-partner.google.com>,
        Daniel Vetter <daniel@...ll.ch>,
        Bas Nieuwenhuizen <bas@...nieuwenhuizen.nl>,
        "Deucher, Alexander" <Alexander.Deucher@....com>,
        Stéphane Marchesin <marcheu@...omium.org>,
        "Kazlauskas, Nicholas" <Nicholas.Kazlauskas@....com>,
        "Wentland, Harry" <Harry.Wentland@....com>,
        Mark Yacoub <markyacoub@...gle.com>
Subject: RE: [PATCH v2] drm/amdgpu: fix that issue that the number of the crtc
 of the 3250c is not correct

[AMD Official Use Only]

Hi Chandan,

This issue we found on the Zork project which uses the kernel 5.4 on. So I just implemented it on kernel 5.4.
For finding out which is 3250c, I referenced the function which is implemented from another function.
Below is the part where I found it.

drivers/gpu/drm/amd/amdgpu/amdgpu_device.c-
	case CHIP_RAVEN:
		if (adev->rev_id >= 8)
			chip_name = "raven2";
		else if (adev->pdev->device == 0x15d8)
			chip_name = "picasso";
		else
			chip_name = "raven";
		break;

BR,
Ryan Lin.

-----Original Message-----
From: VURDIGERENATARAJ, CHANDAN <CHANDAN.VURDIGERENATARAJ@....com> 
Sent: Wednesday, March 30, 2022 12:30 PM
To: Lin, Tsung-hua (Ryan) <Tsung-hua.Lin@....com>
Cc: David (ChunMing) Zhou <David1.Zhou@....com>; Drew Davenport <ddavenport@...omium.org>; Li, Sun peng (Leo) <Sunpeng.Li@....com>; Li, Leon <Leon.Li@....com>; dri-devel@...ts.freedesktop.org; Siqueira, Rodrigo <Rodrigo.Siqueira@....com>; linux-kernel@...r.kernel.org; amd-gfx@...ts.freedesktop.org; Koenig, Christian <Christian.Koenig@....com>; David Airlie <airlied@...ux.ie>; Sean Paul <seanpaul@...omium.org>; Louis Li <ching-shih.li@....corp-partner.google.com>; Daniel Vetter <daniel@...ll.ch>; Bas Nieuwenhuizen <bas@...nieuwenhuizen.nl>; Deucher, Alexander <Alexander.Deucher@....com>; Stéphane Marchesin <marcheu@...omium.org>; Kazlauskas, Nicholas <Nicholas.Kazlauskas@....com>; Wentland, Harry <Harry.Wentland@....com>; Lin, Tsung-hua (Ryan) <Tsung-hua.Lin@....com>; Mark Yacoub <markyacoub@...gle.com>
Subject: RE: [PATCH v2] drm/amdgpu: fix that issue that the number of the crtc of the 3250c is not correct


Hi Ryan,

Is this change applicable on a specific kernel version?
On latest I see IP DISCOVERY based impl for CHIP_RAVEN.

>[Why]
>External displays take priority over internal display when there are fewer display controllers than displays.
>
> [How]
>The root cause is because of that number of the crtc is not correct.
>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.
>
>v2:
>   - remove unnecessary comments and Id
>
>Signed-off-by: Ryan Lin <tsung-hua.lin@....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) {

May I know what this ">=8" indicate? Also, should it be external_rev_id if its based on old version?

>+			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)
>--
>2.25.1
>

BR,
Chandan V N