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From: "Lukáš Krejčí" <lskrejci@gmail.com>
To: sunpeng.li@amd.com, amd-gfx@lists.freedesktop.org,
	dri-devel@lists.freedesktop.org
Cc: Anthony.Koo@amd.com
Subject: Re: [PATCH v2] drm/amdgpu: Add DC feature mask to disable fractional pwm
Date: Wed, 23 Oct 2019 16:19:48 +0200	[thread overview]
Message-ID: <eb513969cc86a42a9be95e4ff7f3473eb24d6d4a.camel@gmail.com> (raw)
In-Reply-To: <20191021194414.24627-1-sunpeng.li@amd.com>

On Mon, 2019-10-21 at 15:44 -0400, sunpeng.li@amd.com wrote:
> From: Leo Li <sunpeng.li@amd.com>
> 
> [Why]
> 
> Some LED panel drivers might not like fractional PWM. In such cases,
> backlight flickering may be observed.
> 
> [How]
> 
> Add a DC feature mask to disable fractional PWM, and associate it with
> the preexisting dc_config flag.
> 
> The flag is only plumbed through the dmcu firmware, so plumb it through
> the driver path as well.
> 
> To disable, add the following to the linux cmdline:
> amdgpu.dcfeaturemask=0x4
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204957
> Signed-off-by: Leo Li <sunpeng.li@amd.com>
> ---
> 
> v2: Add bugzilla link
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
>  drivers/gpu/drm/amd/display/dc/dce/dce_abm.c      | 4 ++++
>  drivers/gpu/drm/amd/include/amd_shared.h          | 1 +
>  3 files changed, 8 insertions(+)

Tested on Ubuntu 19.04, vanilla v5.3.7 kernel with the patch applied
and amdgpu.dcfeaturemask=0x4 added to the kernel command line, no
issues after 8 reboots. (The issue could be reproduced without
amdgpu.dcfeaturemask=0x4 on first boot.)

Tested-by: Lukáš Krejčí <lskrejci@gmail.com>

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel

WARNING: multiple messages have this Message-ID (diff)
From: "Lukáš Krejčí" <lskrejci@gmail.com>
To: sunpeng.li@amd.com, amd-gfx@lists.freedesktop.org,
	 dri-devel@lists.freedesktop.org
Cc: harry.wentland@amd.com, Anthony.Koo@amd.com
Subject: Re: [PATCH v2] drm/amdgpu: Add DC feature mask to disable fractional pwm
Date: Wed, 23 Oct 2019 16:19:48 +0200	[thread overview]
Message-ID: <eb513969cc86a42a9be95e4ff7f3473eb24d6d4a.camel@gmail.com> (raw)
Message-ID: <20191023141948.KW2NkXA8kqDrgN7PWgZ8kV4j8YUWxd6MMaYWzibRer0@z> (raw)
In-Reply-To: <20191021194414.24627-1-sunpeng.li@amd.com>

On Mon, 2019-10-21 at 15:44 -0400, sunpeng.li@amd.com wrote:
> From: Leo Li <sunpeng.li@amd.com>
> 
> [Why]
> 
> Some LED panel drivers might not like fractional PWM. In such cases,
> backlight flickering may be observed.
> 
> [How]
> 
> Add a DC feature mask to disable fractional PWM, and associate it with
> the preexisting dc_config flag.
> 
> The flag is only plumbed through the dmcu firmware, so plumb it through
> the driver path as well.
> 
> To disable, add the following to the linux cmdline:
> amdgpu.dcfeaturemask=0x4
> 
> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=204957
> Signed-off-by: Leo Li <sunpeng.li@amd.com>
> ---
> 
> v2: Add bugzilla link
> 
>  drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 +++
>  drivers/gpu/drm/amd/display/dc/dce/dce_abm.c      | 4 ++++
>  drivers/gpu/drm/amd/include/amd_shared.h          | 1 +
>  3 files changed, 8 insertions(+)

Tested on Ubuntu 19.04, vanilla v5.3.7 kernel with the patch applied
and amdgpu.dcfeaturemask=0x4 added to the kernel command line, no
issues after 8 reboots. (The issue could be reproduced without
amdgpu.dcfeaturemask=0x4 on first boot.)

Tested-by: Lukáš Krejčí <lskrejci@gmail.com>

_______________________________________________
amd-gfx mailing list
amd-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/amd-gfx

  parent reply	other threads:[~2019-10-23 14:19 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-21 19:37 [PATCH] drm/amdgpu: Add DC feature mask to disable fractional pwm sunpeng.li-5C7GfCeVMHo
     [not found] ` <20191021193743.24339-1-sunpeng.li-5C7GfCeVMHo@public.gmane.org>
2019-10-21 19:44   ` [PATCH v2] " sunpeng.li-5C7GfCeVMHo
2019-10-22 14:15     ` Koo, Anthony
2019-10-23 14:19     ` Lukáš Krejčí [this message]
2019-10-23 14:19       ` Lukáš Krejčí
2019-10-23 15:53       ` Li, Sun peng (Leo)
2019-10-23 15:53         ` Li, Sun peng (Leo)

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