linux-kernel - Re: [PATCH] drm/bochs: switch fb_ops over to use drm_fb_helper_cfb helpers

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Message-ID: <20170703081116.rub4ty5ewpi5af3o@phenom.ffwll.local>
Date:   Mon, 3 Jul 2017 10:11:16 +0200
From:   Daniel Vetter <daniel@...ll.ch>
To:     Mark Cave-Ayland <mark.cave-ayland@...nde.co.uk>
Cc:     dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        kraxel@...hat.com
Subject: Re: [PATCH] drm/bochs: switch fb_ops over to use drm_fb_helper_cfb
 helpers

On Sun, Jul 02, 2017 at 10:52:43PM +0100, Mark Cave-Ayland wrote:
> The current drm_fb_helper_sys helpers referenced in fb_ops assume that the
> video memory is in system RAM. This is not the case for sparc which uses direct
> physical memory accesses for IO memory and causes the bochs_drm module to panic
> immediately upon startup as it tries to initialise the framebuffer.
> 
> Switching fb_ops over to use the drm_fb_helper_cfb helpers ensures that the
> correct accesses are used on sparc, fixing the panic and allowing the
> bochs_drm module to function under qemu-system-sparc64.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@...nde.co.uk>

So is this generally true for bochs, or is this now going to broken
platforms where the bochs framebuffer is in system memory?

I'm not entirely clear on that from your commit message ...

Thanks, Daniel

> ---
>  drivers/gpu/drm/bochs/bochs_fbdev.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bochs/bochs_fbdev.c b/drivers/gpu/drm/bochs/bochs_fbdev.c
> index 932a769..d3a75c2 100644
> --- a/drivers/gpu/drm/bochs/bochs_fbdev.c
> +++ b/drivers/gpu/drm/bochs/bochs_fbdev.c
> @@ -23,9 +23,9 @@ static int bochsfb_mmap(struct fb_info *info,
>  static struct fb_ops bochsfb_ops = {
>  	.owner = THIS_MODULE,
>  	DRM_FB_HELPER_DEFAULT_OPS,
> -	.fb_fillrect = drm_fb_helper_sys_fillrect,
> -	.fb_copyarea = drm_fb_helper_sys_copyarea,
> -	.fb_imageblit = drm_fb_helper_sys_imageblit,
> +	.fb_fillrect = drm_fb_helper_cfb_fillrect,
> +	.fb_copyarea = drm_fb_helper_cfb_copyarea,
> +	.fb_imageblit = drm_fb_helper_cfb_imageblit,
>  	.fb_mmap = bochsfb_mmap,
>  };
>  
> -- 
> 1.7.10.4
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel

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

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