Re: [PATCH] drm/i915: Stop using I915_TILING_* in client blit selftest

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Thu, Sep 30, 2021 at 05:58:16PM -0700, Matt Roper wrote:
> The I915_TILING_* definitions in the uapi header are intended solely for
> tiling modes that are visible to the old de-tiling fence ioctls.  Since
> modern hardware does not support de-tiling fences, we should not add new
> definitions for new tiling types going forward.  However we do want the
> client blit selftest to eventually cover other new tiling modes (such as
> Tile4), so switch it to using its own enum of tiling modes.
> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> ---
>  .../i915/gem/selftests/i915_gem_client_blt.c  | 29 ++++++++++++-------
>  include/uapi/drm/i915_drm.h                   |  6 ++++
>  2 files changed, 24 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> index ecbcbb86ae1e..8402ed925a69 100644
> --- a/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> +++ b/drivers/gpu/drm/i915/gem/selftests/i915_gem_client_blt.c
> @@ -17,13 +17,20 @@
>  #include "huge_gem_object.h"
>  #include "mock_context.h"
>  
> +enum client_tiling {
> +	CLIENT_TILING_LINEAR,
> +	CLIENT_TILING_X,
> +	CLIENT_TILING_Y,
> +	CLIENT_NUM_TILING_TYPES
> +};
> +
>  #define WIDTH 512
>  #define HEIGHT 32
>  
>  struct blit_buffer {
>  	struct i915_vma *vma;
>  	u32 start_val;
> -	u32 tiling;
> +	enum client_tiling tiling;
>  };
>  
>  struct tiled_blits {
> @@ -53,9 +60,9 @@ static int prepare_blit(const struct tiled_blits *t,
>  	*cs++ = MI_LOAD_REGISTER_IMM(1);
>  	*cs++ = i915_mmio_reg_offset(BCS_SWCTRL);
>  	cmd = (BCS_SRC_Y | BCS_DST_Y) << 16;
> -	if (src->tiling == I915_TILING_Y)
> +	if (src->tiling == CLIENT_TILING_Y)
>  		cmd |= BCS_SRC_Y;
> -	if (dst->tiling == I915_TILING_Y)
> +	if (dst->tiling == CLIENT_TILING_Y)
>  		cmd |= BCS_DST_Y;
>  	*cs++ = cmd;
>  
> @@ -172,7 +179,7 @@ static int tiled_blits_create_buffers(struct tiled_blits *t,
>  
>  		t->buffers[i].vma = vma;
>  		t->buffers[i].tiling =
> -			i915_prandom_u32_max_state(I915_TILING_Y + 1, prng);
> +			i915_prandom_u32_max_state(CLIENT_TILING_Y + 1, prng);
>  	}
>  
>  	return 0;
> @@ -197,17 +204,17 @@ static u64 swizzle_bit(unsigned int bit, u64 offset)
>  static u64 tiled_offset(const struct intel_gt *gt,
>  			u64 v,
>  			unsigned int stride,
> -			unsigned int tiling)
> +			enum client_tiling tiling)
>  {
>  	unsigned int swizzle;
>  	u64 x, y;
>  
> -	if (tiling == I915_TILING_NONE)
> +	if (tiling == CLIENT_TILING_LINEAR)
>  		return v;
>  
>  	y = div64_u64_rem(v, stride, &x);
>  
> -	if (tiling == I915_TILING_X) {
> +	if (tiling == CLIENT_TILING_X) {
>  		v = div64_u64_rem(y, 8, &y) * stride * 8;
>  		v += y * 512;
>  		v += div64_u64_rem(x, 512, &x) << 12;
> @@ -244,12 +251,12 @@ static u64 tiled_offset(const struct intel_gt *gt,
>  	return v;
>  }
>  
> -static const char *repr_tiling(int tiling)
> +static const char *repr_tiling(enum client_tiling tiling)
>  {
>  	switch (tiling) {
> -	case I915_TILING_NONE: return "linear";
> -	case I915_TILING_X: return "X";
> -	case I915_TILING_Y: return "Y";
> +	case CLIENT_TILING_LINEAR: return "linear";
> +	case CLIENT_TILING_X: return "X";
> +	case CLIENT_TILING_Y: return "Y";
>  	default: return "unknown";
>  	}
>  }
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index bde5860b3686..00311a63068e 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -1522,6 +1522,12 @@ struct drm_i915_gem_caching {
>  #define I915_TILING_NONE	0
>  #define I915_TILING_X		1
>  #define I915_TILING_Y		2
> +/*
> + * Do not add new tiling types here.  The I915_TILING_* values are for
> + * de-tiling fence registers that no longer exist on modern platforms.  Although
> + * the hardware may support new types of tiling in general (e.g., Tile4), we
> + * do not need to add them to the uapi that is specific to now-defunct ioctls.
> + */
>  #define I915_TILING_LAST	I915_TILING_Y

I think we should split this one into a separate patch to give it
some visibility. The people who care about gem uapi seem to be in
some kind of early winter hibernation and no one read this.

Apart from that
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

>  
>  #define I915_BIT_6_SWIZZLE_NONE		0
> -- 
> 2.33.0

-- 
Ville Syrjälä
Intel