[PATCH 3/4] drm/mgag200: Add workaround for HW that does not support 'startadd'

[Daniel Vetter]

On Tue, Nov 26, 2019 at 08:25:44AM +0100, Thomas Zimmermann wrote:
> There's at least one system that does not interpret the value of
> the device's 'startadd' field correctly, which leads to incorrectly
> displayed scanout buffers. Always placing the active scanout buffer
> at offset 0 works around the problem.
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> Reported-by: John Donnelly <john.p.donnelly at oracle.com>
> Link: https://gitlab.freedesktop.org/drm/misc/issues/7

Tested-by: John Donnelly <john.p.donnelly at oracle.com>

(Not quite this patch, but pretty much the logic, so counts).

Fixes: 81da87f63a1e ("drm: Replace drm_gem_vram_push_to_system() with kunmap + unpin")
Cc: <stable at vger.kernel.org> # v5.3+

Also you need the stable line on both prep patches too. For next time
around,

$ dim fixes 81da87f63a1e

will generate all the stuff you need, including a good set of suggested
Cc: you should have.

On the first 3 patches, with all that stuff added:

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

Please push these to drm-misc-next-fixes so they get backported as quickly
as possible.
-Daniel

> ---
>  drivers/gpu/drm/mgag200/mgag200_drv.c | 36 ++++++++++++++++++++++++++-
>  drivers/gpu/drm/mgag200/mgag200_drv.h |  3 +++
>  2 files changed, 38 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
> index 397f8b0a9af8..d43951caeea0 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
> @@ -30,6 +30,8 @@ module_param_named(modeset, mgag200_modeset, int, 0400);
>  static struct drm_driver driver;
>  
>  static const struct pci_device_id pciidlist[] = {
> +	{ PCI_VENDOR_ID_MATROX, 0x522, PCI_VENDOR_ID_SUN, 0x4852, 0, 0,
> +		G200_SE_A | MGAG200_FLAG_HW_BUG_NO_STARTADD},
>  	{ PCI_VENDOR_ID_MATROX, 0x522, PCI_ANY_ID, PCI_ANY_ID, 0, 0, G200_SE_A },
>  	{ PCI_VENDOR_ID_MATROX, 0x524, PCI_ANY_ID, PCI_ANY_ID, 0, 0, G200_SE_B },
>  	{ PCI_VENDOR_ID_MATROX, 0x530, PCI_ANY_ID, PCI_ANY_ID, 0, 0, G200_EV },
> @@ -60,6 +62,35 @@ static void mga_pci_remove(struct pci_dev *pdev)
>  
>  DEFINE_DRM_GEM_FOPS(mgag200_driver_fops);
>  
> +static bool mgag200_pin_bo_at_0(const struct mga_device *mdev)
> +{
> +	return mdev->flags & MGAG200_FLAG_HW_BUG_NO_STARTADD;
> +}
> +
> +int mgag200_driver_dumb_create(struct drm_file *file,
> +			       struct drm_device *dev,
> +			       struct drm_mode_create_dumb *args)
> +{
> +	struct mga_device *mdev = dev->dev_private;
> +	unsigned long pg_align;
> +
> +	if (WARN_ONCE(!dev->vram_mm, "VRAM MM not initialized"))
> +		return -EINVAL;
> +
> +	pg_align = 0ul;
> +
> +	/*
> +	 * Aligning scanout buffers to the size of the video ram forces
> +	 * placement at offset 0. Works around a bug where HW does not
> +	 * respect 'startadd' field.
> +	 */
> +	if (mgag200_pin_bo_at_0(mdev))
> +		pg_align = PFN_UP(mdev->mc.vram_size);
> +
> +	return drm_gem_vram_fill_create_dumb(file, dev, &dev->vram_mm->bdev,
> +					     pg_align, false, args);
> +}
> +
>  static struct drm_driver driver = {
>  	.driver_features = DRIVER_GEM | DRIVER_MODESET,
>  	.load = mgag200_driver_load,
> @@ -71,7 +102,10 @@ static struct drm_driver driver = {
>  	.major = DRIVER_MAJOR,
>  	.minor = DRIVER_MINOR,
>  	.patchlevel = DRIVER_PATCHLEVEL,
> -	DRM_GEM_VRAM_DRIVER
> +	.debugfs_init = drm_vram_mm_debugfs_init,
> +	.dumb_create = mgag200_driver_dumb_create,
> +	.dumb_map_offset = drm_gem_vram_driver_dumb_mmap_offset,
> +	.gem_prime_mmap = drm_gem_prime_mmap,
>  };
>  
>  static struct pci_driver mgag200_pci_driver = {
> diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h
> index 4b4f9ce74a84..aa32aad222c2 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.h
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.h
> @@ -150,6 +150,9 @@ enum mga_type {
>  	G200_EW3,
>  };
>  
> +/* HW does not handle 'startadd' field correct. */
> +#define MGAG200_FLAG_HW_BUG_NO_STARTADD	(1ul << 8)
> +
>  #define MGAG200_TYPE_MASK	(0x000000ff)
>  #define MGAG200_FLAG_MASK	(0x00ffff00)
>  
> -- 
> 2.23.0
> 

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