[Intel-gfx] [PATCH v2 1/8] drm/i915: Fix unsigned overflow when calculating total data rate
Ville Syrjälä
ville.syrjala at linux.intel.com
Thu Oct 18 14:53:13 UTC 2018
On Thu, Oct 18, 2018 at 01:51:27PM +0200, Maarten Lankhorst wrote:
> On gen11, we can definitely smash the 32-bits barrier with just a
> when we enable all planes in the next patch.
>
> Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
I guess the per-plane data rate is still <32bit (because it doesn't
account for the refresh rate). But making everything 64bit seems safest.
Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Now we could also improve the per-plane data rate to include the
refresh rate and get rid of inaccurate drm_mode_vrefresh() in there.
> ---
> drivers/gpu/drm/i915/intel_pm.c | 47 +++++++++++++++------------------
> 1 file changed, 22 insertions(+), 25 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 67a4d0735291..3b136fdfd24f 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3784,7 +3784,7 @@ bool intel_can_enable_sagv(struct drm_atomic_state *state)
>
> static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
> const struct intel_crtc_state *cstate,
> - const unsigned int total_data_rate,
> + const u64 total_data_rate,
> const int num_active,
> struct skl_ddb_allocation *ddb)
> {
> @@ -3798,12 +3798,12 @@ static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
> return ddb_size - 4; /* 4 blocks for bypass path allocation */
>
> adjusted_mode = &cstate->base.adjusted_mode;
> - total_data_bw = (u64)total_data_rate * drm_mode_vrefresh(adjusted_mode);
> + total_data_bw = total_data_rate * drm_mode_vrefresh(adjusted_mode);
>
> /*
> * 12GB/s is maximum BW supported by single DBuf slice.
> */
> - if (total_data_bw >= GBps(12) || num_active > 1) {
> + if (num_active > 1 || total_data_bw >= GBps(12)) {
> ddb->enabled_slices = 2;
> } else {
> ddb->enabled_slices = 1;
> @@ -3816,7 +3816,7 @@ static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
> static void
> skl_ddb_get_pipe_allocation_limits(struct drm_device *dev,
> const struct intel_crtc_state *cstate,
> - const unsigned int total_data_rate,
> + const u64 total_data_rate,
> struct skl_ddb_allocation *ddb,
> struct skl_ddb_entry *alloc, /* out */
> int *num_active /* out */)
> @@ -4139,7 +4139,7 @@ int skl_check_pipe_max_pixel_rate(struct intel_crtc *intel_crtc,
> return 0;
> }
>
> -static unsigned int
> +static u64
> skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
> const struct drm_plane_state *pstate,
> const int plane)
> @@ -4151,6 +4151,7 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
> struct drm_framebuffer *fb;
> u32 format;
> uint_fixed_16_16_t down_scale_amount;
> + u64 rate;
>
> if (!intel_pstate->base.visible)
> return 0;
> @@ -4177,28 +4178,26 @@ skl_plane_relative_data_rate(const struct intel_crtc_state *cstate,
> height /= 2;
> }
>
> - data_rate = width * height * fb->format->cpp[plane];
> + data_rate = width * height;
>
> down_scale_amount = skl_plane_downscale_amount(cstate, intel_pstate);
>
> - return mul_round_up_u32_fixed16(data_rate, down_scale_amount);
> + rate = mul_round_up_u32_fixed16(data_rate, down_scale_amount);
> +
> + rate *= fb->format->cpp[plane];
> + return rate;
> }
>
> -/*
> - * We don't overflow 32 bits. Worst case is 3 planes enabled, each fetching
> - * a 8192x4096 at 32bpp framebuffer:
> - * 3 * 4096 * 8192 * 4 < 2^32
> - */
> -static unsigned int
> +static u64
> skl_get_total_relative_data_rate(struct intel_crtc_state *intel_cstate,
> - unsigned int *plane_data_rate,
> - unsigned int *uv_plane_data_rate)
> + u64 *plane_data_rate,
> + u64 *uv_plane_data_rate)
> {
> struct drm_crtc_state *cstate = &intel_cstate->base;
> struct drm_atomic_state *state = cstate->state;
> struct drm_plane *plane;
> const struct drm_plane_state *pstate;
> - unsigned int total_data_rate = 0;
> + u64 total_data_rate = 0;
>
> if (WARN_ON(!state))
> return 0;
> @@ -4206,7 +4205,7 @@ skl_get_total_relative_data_rate(struct intel_crtc_state *intel_cstate,
> /* Calculate and cache data rate for each plane */
> drm_atomic_crtc_state_for_each_plane_state(plane, pstate, cstate) {
> enum plane_id plane_id = to_intel_plane(plane)->id;
> - unsigned int rate;
> + u64 rate;
>
> /* packed/y */
> rate = skl_plane_relative_data_rate(intel_cstate,
> @@ -4325,11 +4324,11 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> uint16_t alloc_size, start;
> uint16_t minimum[I915_MAX_PLANES] = {};
> uint16_t uv_minimum[I915_MAX_PLANES] = {};
> - unsigned int total_data_rate;
> + u64 total_data_rate;
> enum plane_id plane_id;
> int num_active;
> - unsigned int plane_data_rate[I915_MAX_PLANES] = {};
> - unsigned int uv_plane_data_rate[I915_MAX_PLANES] = {};
> + u64 plane_data_rate[I915_MAX_PLANES] = {};
> + u64 uv_plane_data_rate[I915_MAX_PLANES] = {};
> uint16_t total_min_blocks = 0;
>
> /* Clear the partitioning for disabled planes. */
> @@ -4388,7 +4387,7 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
>
> start = alloc->start;
> for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> - unsigned int data_rate, uv_data_rate;
> + u64 data_rate, uv_data_rate;
> uint16_t plane_blocks, uv_plane_blocks;
>
> if (plane_id == PLANE_CURSOR)
> @@ -4402,8 +4401,7 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> * result is < available as data_rate / total_data_rate < 1
> */
> plane_blocks = minimum[plane_id];
> - plane_blocks += div_u64((uint64_t)alloc_size * data_rate,
> - total_data_rate);
> + plane_blocks += alloc_size * data_rate / total_data_rate;
>
> /* Leave disabled planes at (0,0) */
> if (data_rate) {
> @@ -4417,8 +4415,7 @@ skl_allocate_pipe_ddb(struct intel_crtc_state *cstate,
> uv_data_rate = uv_plane_data_rate[plane_id];
>
> uv_plane_blocks = uv_minimum[plane_id];
> - uv_plane_blocks += div_u64((uint64_t)alloc_size * uv_data_rate,
> - total_data_rate);
> + uv_plane_blocks += alloc_size * uv_data_rate / total_data_rate;
>
> if (uv_data_rate) {
> ddb->uv_plane[pipe][plane_id].start = start;
> --
> 2.19.1
>
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--
Ville Syrjälä
Intel
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