Re: [PATCH] drm/radeon: Update pitch for page flip

From: "Christian König" <christian.koenig@amd.com>
To: Zhenneng Li <lizhenneng@kylinos.cn>
Cc: Alex Deucher <alexander.deucher@amd.com>,
	"Pan, Xinhui" <Xinhui.Pan@amd.com>,
	David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>,
	amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] drm/radeon: Update pitch for page flip
Date: Mon, 2 Aug 2021 10:12:47 +0200	[thread overview]
Message-ID: <e6e77cfb-4e6b-c30e-ae7c-ac84b82c9a75@amd.com> (raw)
In-Reply-To: <20210802074310.1526526-1-lizhenneng@kylinos.cn>

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Am 02.08.21 um 09:43 schrieb Zhenneng Li:
> When primary bo is updated, crtc's pitch may
> have not been updated, this will lead to show
> disorder content when user changes display mode,
> we update crtc's pitch in page flip to avoid
> this bug.
> This refers to amdgpu's pageflip.

Alex is the expert to ask about that code, but I'm not sure if that is 
really correct for the old hardware.

As far as I know the crtc's pitch should not change during a page flip, 
but only during a full mode set.

So could you elaborate a bit more how you trigger this?

Thanks,
Christian.

>
> Cc: Alex Deucher <alexander.deucher@amd.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Cc: "Pan, Xinhui" <Xinhui.Pan@amd.com>
> Cc: David Airlie <airlied@linux.ie>
> Cc: Daniel Vetter <daniel@ffwll.ch>
> Cc: amd-gfx@lists.freedesktop.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Zhenneng Li <lizhenneng@kylinos.cn>
> ---
>   drivers/gpu/drm/radeon/evergreen.c | 8 +++++++-
>   1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
> index 36a888e1b179..eeb590d2dec2 100644
> --- a/drivers/gpu/drm/radeon/evergreen.c
> +++ b/drivers/gpu/drm/radeon/evergreen.c
> @@ -28,6 +28,7 @@
>   
>   #include <drm/drm_vblank.h>
>   #include <drm/radeon_drm.h>
> +#include <drm/drm_fourcc.h>
>   
>   #include "atom.h"
>   #include "avivod.h"
> @@ -1414,10 +1415,15 @@ void evergreen_page_flip(struct radeon_device *rdev, int crtc_id, u64 crtc_base,
>   			 bool async)
>   {
>   	struct radeon_crtc *radeon_crtc = rdev->mode_info.crtcs[crtc_id];
> +	struct drm_framebuffer *fb = radeon_crtc->base.primary->fb;
>   
> -	/* update the scanout addresses */
> +	/* flip at hsync for async, default is vsync */
>   	WREG32(EVERGREEN_GRPH_FLIP_CONTROL + radeon_crtc->crtc_offset,
>   	       async ? EVERGREEN_GRPH_SURFACE_UPDATE_H_RETRACE_EN : 0);
> +	/* update pitch */
> +	WREG32(EVERGREEN_GRPH_PITCH + radeon_crtc->crtc_offset,
> +	       fb->pitches[0] / fb->format->cpp[0]);
> +	/* update the scanout addresses */
>   	WREG32(EVERGREEN_GRPH_PRIMARY_SURFACE_ADDRESS_HIGH + radeon_crtc->crtc_offset,
>   	       upper_32_bits(crtc_base));
>   	WREG32(EVERGREEN_GRPH_PRIMARY_SURFACE_ADDRESS + radeon_crtc->crtc_offset,
>
> No virus found
> 		Checked by Hillstone Network AntiVirus

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