Re: [PATCH 4/4] drm/mgag200: Add module parameter to pin all buffers at offset 0

[Daniel Vetter <daniel@ffwll.ch>]

On Tue, Nov 26, 2019 at 08:25:45AM +0100, Thomas Zimmermann wrote:
> For hardware that does not interpret the startadd field correctly,
> add the module parameter 'hw_bug_no_startadd', which enables the
> workaround.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
> ---
>  drivers/gpu/drm/mgag200/mgag200_drv.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
> index d43951caeea0..79836b09a54a 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
> @@ -27,6 +27,10 @@ int mgag200_modeset = -1;
>  MODULE_PARM_DESC(modeset, "Disable/Enable modesetting");
>  module_param_named(modeset, mgag200_modeset, int, 0400);
>  
> +int mgag200_hw_bug_no_startadd = -1;
> +MODULE_PARM_DESC(modeset, "HW does not interpret scanout-buffer start address correctly");
> +module_param_named(hw_bug_no_startadd, mgag200_hw_bug_no_startadd, int, 0400);
> +
>  static struct drm_driver driver;
>  
>  static const struct pci_device_id pciidlist[] = {
> @@ -64,6 +68,10 @@ DEFINE_DRM_GEM_FOPS(mgag200_driver_fops);
>  
>  static bool mgag200_pin_bo_at_0(const struct mga_device *mdev)
>  {

I'd add a infor printing if the module option is non-zero that people
should submit a bug report if this fixes their issue. We don't want people
fixing bugs with module options, stuff should work by default.

With that addressed:

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>

> +	if (!mgag200_hw_bug_no_startadd)
> +		return false;
> +	else if (mgag200_hw_bug_no_startadd > 0)
> +		return true;
>  	return mdev->flags & MGAG200_FLAG_HW_BUG_NO_STARTADD;
>  }
>  
> -- 
> 2.23.0
> 

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