linux-kernel - Re: [PATCH 2/2] drm/bochs: fix framebuffer setup.

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Message-ID: <20190626162957.GW12905@phenom.ffwll.local>
Date:   Wed, 26 Jun 2019 18:29:57 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Gerd Hoffmann <kraxel@...hat.com>
Cc:     dri-devel@...ts.freedesktop.org, tzimmermann@...e.de,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        "open list:DRM DRIVER FOR BOCHS VIRTUAL GPU" 
        <virtualization@...ts.linux-foundation.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] drm/bochs: fix framebuffer setup.

On Wed, Jun 26, 2019 at 08:55:51AM +0200, Gerd Hoffmann wrote:
> If bo->width doesn't match fb->width the driver fails to configure
> the display correctly, resulting in a scrambled display.  Fix it.
> 
> Signed-off-by: Gerd Hoffmann <kraxel@...hat.com>
> ---
>  drivers/gpu/drm/bochs/bochs.h     |  2 +-
>  drivers/gpu/drm/bochs/bochs_hw.c  | 13 +++++++++----
>  drivers/gpu/drm/bochs/bochs_kms.c |  1 +
>  3 files changed, 11 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bochs/bochs.h b/drivers/gpu/drm/bochs/bochs.h
> index cc35d492142c..78c0283496cc 100644
> --- a/drivers/gpu/drm/bochs/bochs.h
> +++ b/drivers/gpu/drm/bochs/bochs.h
> @@ -86,7 +86,7 @@ void bochs_hw_setmode(struct bochs_device *bochs,
>  void bochs_hw_setformat(struct bochs_device *bochs,
>  			const struct drm_format_info *format);
>  void bochs_hw_setbase(struct bochs_device *bochs,
> -		      int x, int y, u64 addr);
> +		      int x, int y, int fbwidth, u64 addr);
>  int bochs_hw_load_edid(struct bochs_device *bochs);
>  
>  /* bochs_mm.c */
> diff --git a/drivers/gpu/drm/bochs/bochs_hw.c b/drivers/gpu/drm/bochs/bochs_hw.c
> index 791ab2f79947..141aa02962d3 100644
> --- a/drivers/gpu/drm/bochs/bochs_hw.c
> +++ b/drivers/gpu/drm/bochs/bochs_hw.c
> @@ -255,16 +255,21 @@ void bochs_hw_setformat(struct bochs_device *bochs,
>  }
>  
>  void bochs_hw_setbase(struct bochs_device *bochs,
> -		      int x, int y, u64 addr)
> +		      int x, int y, int fbwidth, u64 addr)
>  {
> -	unsigned long offset = (unsigned long)addr +
> +	unsigned long offset;
> +	unsigned int vx, vy;
> +
> +	bochs->stride = fbwidth * (bochs->bpp / 8);
> +	offset = (unsigned long)addr +
>  		y * bochs->stride +
>  		x * (bochs->bpp / 8);
> -	int vy = offset / bochs->stride;
> -	int vx = (offset % bochs->stride) * 8 / bochs->bpp;
> +	vy = offset / bochs->stride;
> +	vx = (offset % bochs->stride) * 8 / bochs->bpp;
>  
>  	DRM_DEBUG_DRIVER("x %d, y %d, addr %llx -> offset %lx, vx %d, vy %d\n",
>  			 x, y, addr, offset, vx, vy);
> +	bochs_dispi_write(bochs, VBE_DISPI_INDEX_VIRT_WIDTH, fbwidth);
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_X_OFFSET, vx);
>  	bochs_dispi_write(bochs, VBE_DISPI_INDEX_Y_OFFSET, vy);
>  }
> diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.c
> index 5904eddc83a5..1f6aa11a1dc9 100644
> --- a/drivers/gpu/drm/bochs/bochs_kms.c
> +++ b/drivers/gpu/drm/bochs/bochs_kms.c
> @@ -36,6 +36,7 @@ static void bochs_plane_update(struct bochs_device *bochs,
>  	bochs_hw_setbase(bochs,
>  			 state->crtc_x,
>  			 state->crtc_y,
> +			 gbo->width,

You want the dimensions of the drm_framebuffer here, not something from
the underlying gem bo.

>  			 gbo->bo.offset);

I think same here, or at least additionally take into account both
drm_framebuffer offset _and_ vram offset.
-Daniel

>  	bochs_hw_setformat(bochs, state->fb->format);
>  }
> -- 
> 2.18.1
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch