[Intel-gfx] [PATCH v2 1/8] drm/i915: Fix unsigned overflow when calculating total data rate
Maarten Lankhorst
maarten.lankhorst at linux.intel.com
Fri Oct 19 12:58:07 UTC 2018
Op 18-10-18 om 16:53 schreef Ville Syrjälä:
> 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.
With the current limits, we're already awfully close if we ever end up with 16 bits per component formats.
> 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.
Yeah would be nice. :)
>> ---
>> 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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