[PATCH 01/11] drm/i915/dsb: Extract intel_dsb_ins_align()

[Jani Nikula]

On Mon, 07 Apr 2025, Chaitanya Kumar Borah <chaitanya.kumar.borah at intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Extract the code that alings the next instruction to the next
> QW boundary into a small helper. I'll have some more uses for
> this later.
>
> Also explain why we don't have to zero out the extra DW.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Chaitanya, your Signed-off-by is *required* in addition.

See https://developercertificate.org/.

BR,
Jani.

> ---
>  drivers/gpu/drm/i915/display/intel_dsb.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
> index 0ddcdedf5453..c166e02b8af0 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> @@ -228,13 +228,25 @@ static bool is_dsb_busy(struct intel_display *display, enum pipe pipe,
>  	return intel_de_read_fw(display, DSB_CTRL(pipe, dsb_id)) & DSB_STATUS_BUSY;
>  }
>  
> +static void intel_dsb_ins_align(struct intel_dsb *dsb)
> +{
> +	/*
> +	 * Every instruction should be 8 byte aligned.
> +	 *
> +	 * The only way to get unaligned free_pos is via
> +	 * intel_dsb_reg_write_indexed() which already
> +	 * makes sure the next dword is zeroed, so no need
> +	 * to clear it here.
> +	 */
> +	dsb->free_pos = ALIGN(dsb->free_pos, 2);
> +}
> +
>  static void intel_dsb_emit(struct intel_dsb *dsb, u32 ldw, u32 udw)
>  {
>  	if (!assert_dsb_has_room(dsb))
>  		return;
>  
> -	/* Every instruction should be 8 byte aligned. */
> -	dsb->free_pos = ALIGN(dsb->free_pos, 2);
> +	intel_dsb_ins_align(dsb);
>  
>  	dsb->ins_start_offset = dsb->free_pos;
>  	dsb->ins[0] = ldw;

-- 
Jani Nikula, Intel