Re: [PATCH v3 19/26] drm/{i915/xe}/writeback: Add a writeback helper to get ggtt address

["Borah, Chaitanya Kumar" <chaitanya.kumar.borah@intel.com>]

On 3/25/2026 4:37 PM, Suraj Kandpal wrote:
> We need the ggtt address offset to write in the WD_SURF register.
> With i915_vma being defined in xe and i915 and both having different
> ways to extract the address this poses an issue.
> Add a helper so that correct function is called to extract address
> depending on xe/i915 driver.
> 
> Signed-off-by: Suraj Kandpal <suraj.kandpal@intel.com>
> ---
>   drivers/gpu/drm/i915/Makefile                       |  1 +
>   drivers/gpu/drm/i915/display/intel_writeback.c      |  3 ++-
>   .../gpu/drm/i915/display/intel_writeback_helper.c   | 12 ++++++++++++
>   .../gpu/drm/i915/display/intel_writeback_helper.h   |  8 ++++++++
>   drivers/gpu/drm/xe/Makefile                         |  3 ++-
>   drivers/gpu/drm/xe/display/xe_writeback_helper.c    | 13 +++++++++++++
>   6 files changed, 38 insertions(+), 2 deletions(-)
>   create mode 100644 drivers/gpu/drm/i915/display/intel_writeback_helper.c
>   create mode 100644 drivers/gpu/drm/i915/display/intel_writeback_helper.h
>   create mode 100644 drivers/gpu/drm/xe/display/xe_writeback_helper.c
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index 1e9140e7713c..a1023de728e5 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -316,6 +316,7 @@ i915-y += \
>   	display/intel_vga.o \
>   	display/intel_wm.o \
>   	display/intel_writeback.o \
> +	display/intel_writeback_helper.o \
>   	display/skl_prefill.o \
>   	display/skl_scaler.o \
>   	display/skl_universal_plane.o \
> diff --git a/drivers/gpu/drm/i915/display/intel_writeback.c b/drivers/gpu/drm/i915/display/intel_writeback.c
> index c79e7330b81c..d3c3716a28a9 100644
> --- a/drivers/gpu/drm/i915/display/intel_writeback.c
> +++ b/drivers/gpu/drm/i915/display/intel_writeback.c
> @@ -1,6 +1,6 @@
>   // SPDX-License-Identifier: MIT
>   /*
> - * Copyright © 2025 Intel Corporation
> + * Copyright © 2026 Intel Corporation
>    */
>   
>   #include <linux/slab.h>
> @@ -25,6 +25,7 @@
>   #include "intel_display_utils.h"
>   #include "intel_fb_pin.h"
>   #include "intel_writeback.h"
> +#include "intel_writeback_helper.h"
>   #include "intel_writeback_reg.h"
>   
>   struct intel_writeback_connector {
> diff --git a/drivers/gpu/drm/i915/display/intel_writeback_helper.c b/drivers/gpu/drm/i915/display/intel_writeback_helper.c
> new file mode 100644
> index 000000000000..f483ed6ffc6b
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_writeback_helper.c
> @@ -0,0 +1,12 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +#include "i915_vma.h"
> +#include "intel_writeback_helper.h"

needs #include <linux/types.h> to build.

> +
> +u32 intel_get_ggtt_addr(struct i915_vma *vma)
> +{
> +	return i915_ggtt_offset(vma);
> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_writeback_helper.h b/drivers/gpu/drm/i915/display/intel_writeback_helper.h
> new file mode 100644
> index 000000000000..b46f437c3875
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/display/intel_writeback_helper.h
> @@ -0,0 +1,8 @@
> +/* SPDX-License-Identifier: MIT */
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +struct i915_vma;
> +
> +u32 intel_get_ggtt_addr(struct i915_vma *vma);
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 2e456070895a..4483e97153ba 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -224,7 +224,8 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
>   	display/xe_initial_plane.o \
>   	display/xe_panic.o \
>   	display/xe_stolen.o \
> -	display/xe_tdf.o
> +	display/xe_tdf.o \
> +	display/xe_writeback_helper.o
>   
>   # Display code shared with i915
>   xe-$(CONFIG_DRM_XE_DISPLAY) += \
> diff --git a/drivers/gpu/drm/xe/display/xe_writeback_helper.c b/drivers/gpu/drm/xe/display/xe_writeback_helper.c
> new file mode 100644
> index 000000000000..5898984b129c
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/display/xe_writeback_helper.c
> @@ -0,0 +1,13 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2026 Intel Corporation
> + */
> +
> +#include "xe_ggtt.h"
> +#include "xe_display_vma.h"
> +#include "intel_writeback_helper.h"
> +
> +u32 intel_get_ggtt_addr(struct i915_vma *vma)
> +{
> +	return lower_32_bits(xe_ggtt_node_addr(vma->node));
> +}