On 11.12.2024 9:29 AM, Neil Armstrong wrote:
> The Adreno GPU Management Unit (GMU) can also scale the DDR Bandwidth
> along the Frequency and Power Domain level, until now we left the OPP
> core scale the OPP bandwidth via the interconnect path.
>
> In order to enable bandwidth voting via the GPU Management
> Unit (GMU), when an opp is set by devfreq we also look for
> the corresponding bandwidth index in the previously generated
> bw_table and pass this value along the frequency index to the GMU.
>
> The GMU also takes another vote called AB which is a 16bit quantized
> value of the floor bandwidth against the maximum supported bandwidth.
>
> The AB is calculated with a default 25% of the bandwidth like the
> downstream implementation too inform the GMU firmware the minimal
> quantity of bandwidth we require for this OPP.
>
> Since we now vote for all resources via the GMU, setting the OPP
> is no more needed, so we can completely skip calling
> dev_pm_opp_set_opp() in this situation.
>
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> Reviewed-by: Akhil P Oommen <quic_akhilpo@xxxxxxxxxxx>
> Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
> ---
> drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 39 +++++++++++++++++++++++++++++++++--
> drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 2 +-
> drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 6 +++---
> drivers/gpu/drm/msm/adreno/a6xx_hfi.h | 5 +++++
> 4 files changed, 46 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index 36696d372a42a27b26a018b19e73bc6d8a4a5235..46ae0ec7a16a41d55755ce04fb32404cdba087be 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> @@ -110,9 +110,11 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
> bool suspended)
> {
> struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu);
> + const struct a6xx_info *info = adreno_gpu->info->a6xx;
> struct a6xx_gpu *a6xx_gpu = to_a6xx_gpu(adreno_gpu);
> struct a6xx_gmu *gmu = &a6xx_gpu->gmu;
> u32 perf_index;
> + u32 bw_index = 0;
> unsigned long gpu_freq;
> int ret = 0;
>
> @@ -125,6 +127,37 @@ void a6xx_gmu_set_freq(struct msm_gpu *gpu, struct dev_pm_opp *opp,
> if (gpu_freq == gmu->gpu_freqs[perf_index])
> break;
>
> + /* If enabled, find the corresponding DDR bandwidth index */
> + if (info->bcms && gmu->nr_gpu_bws > 1) {
if (gmu->nr_gpu_bws)
> + unsigned int bw = dev_pm_opp_get_bw(opp, true, 0);
> +
> + for (bw_index = 0; bw_index < gmu->nr_gpu_bws - 1; bw_index++) {
> + if (bw == gmu->gpu_bw_table[bw_index])
> + break;
> + }
> +
> + /* Vote AB as a fraction of the max bandwidth */
> + if (bw) {
This seems to only be introduced with certain a7xx too.. you should
ping the GMU with HFI_VALUE_GMU_AB_VOTE to check if it's supported
> + u64 tmp;
> +
> + /* For now, vote for 25% of the bandwidth */
> + tmp = bw * 25;
> + do_div(tmp, 100);
> +
> + /*
> + * The AB vote consists of a 16 bit wide quantized level
> + * against the maximum supported bandwidth.
> + * Quantization can be calculated as below:
> + * vote = (bandwidth * 2^16) / max bandwidth
> + */
> + tmp *= MAX_AB_VOTE;
> + do_div(tmp, gmu->gpu_bw_table[gmu->nr_gpu_bws - 1]);
> +
> + bw_index |= AB_VOTE(clamp(tmp, 1, MAX_AB_VOTE));
> + bw_index |= AB_VOTE_ENABLE;
> + }
> + }
BTW, did you dump the values we send to the GMU here and in the RPMh
builder part & validate against downstream?
Konrad
