Messages in this thread |  | | Date | Mon, 2 Dec 2024 09:46:25 +0100 | | From | Neil Armstrong <> | | Subject | Re: [PATCH v3 2/7] drm/msm: adreno: add plumbing to generate bandwidth vote table for GMU |
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On 30/11/2024 22:49, Akhil P Oommen wrote: > On 11/28/2024 3:55 PM, Neil Armstrong wrote: >> The Adreno GPU Management Unit (GMU) can also scale DDR Bandwidth along >> the Frequency and Power Domain level, but by default we leave the >> OPP core scale the interconnect ddr path. >> >> While scaling via the interconnect path was sufficient, newer GPUs >> like the A750 requires specific vote paremeters and bandwidth to >> achieve full functionality. >> >> In order to calculate vote values used by the GPU Management >> Unit (GMU), we need to parse all the possible OPP Bandwidths and >> create a vote value to be sent to the appropriate Bus Control >> Modules (BCMs) declared in the GPU info struct. >> >> This vote value is called IB, while on the othe side the GMU also >> takes another vote called AB which is a 16bit quantized value >> of the bandwidth against the maximum supported bandwidth. >> >> The vote array will then be used to dynamically generate the GMU >> bw_table sent during the GMU power-up. >> >> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org> >> --- >> drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 174 ++++++++++++++++++++++++++++++++++ >> drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 14 +++ >> drivers/gpu/drm/msm/adreno/a6xx_gpu.h | 1 + >> drivers/gpu/drm/msm/adreno/a6xx_hfi.h | 5 + >> 4 files changed, 194 insertions(+) >> >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c >> index 14db7376c712d19446b38152e480bd5a1e0a5198..ee2010a01186721dd377f1655fcf05ddaff77131 100644 >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c >> @@ -9,6 +9,7 @@ >> #include <linux/pm_domain.h> >> #include <linux/pm_opp.h> >> #include <soc/qcom/cmd-db.h> >> +#include <soc/qcom/tcs.h> >> #include <drm/drm_gem.h> >> >> #include "a6xx_gpu.h" >> @@ -1287,6 +1288,131 @@ static int a6xx_gmu_memory_probe(struct a6xx_gmu *gmu) >> return 0; >> } >> >> +/** >> + * struct bcm_db - Auxiliary data pertaining to each Bus Clock Manager (BCM) >> + * @unit: divisor used to convert bytes/sec bw value to an RPMh msg >> + * @width: multiplier used to convert bytes/sec bw value to an RPMh msg >> + * @vcd: virtual clock domain that this bcm belongs to >> + * @reserved: reserved field >> + */ >> +struct bcm_db { >> + __le32 unit; >> + __le16 width; >> + u8 vcd; >> + u8 reserved; >> +}; >> + >> +static u64 bcm_div(u64 num, u32 base) >> +{ >> + /* Ensure that small votes aren't lost. */ >> + if (num && num < base) >> + return 1; >> + >> + do_div(num, base); >> + >> + return num; >> +} >> + >> +static int a6xx_gmu_rpmh_bw_votes_init(const struct a6xx_info *info, >> + struct a6xx_gmu *gmu) >> +{ >> + const struct bcm_db *bcm_data[GMU_MAX_BCMS] = { 0 }; >> + unsigned int bcm_index, bw_index, bcm_count = 0; >> + >> + if (!info->bcms) >> + return 0; >> + >> + /* Retrieve BCM data from cmd-db */ >> + for (bcm_index = 0; bcm_index < GMU_MAX_BCMS; bcm_index++) { >> + size_t count; >> + >> + /* Stop at first unconfigured bcm */ >> + if (!info->bcms[bcm_index].name) >> + break; >> + >> + bcm_data[bcm_index] = cmd_db_read_aux_data( >> + info->bcms[bcm_index].name, >> + &count); >> + if (IS_ERR(bcm_data[bcm_index])) >> + return PTR_ERR(bcm_data[bcm_index]); >> + >> + if (!count) >> + return -EINVAL; >> + >> + ++bcm_count; >> + } >> + >> + /* Generate BCM votes values for each bandwidth & BCM */ >> + for (bw_index = 0; bw_index < gmu->nr_gpu_bws; bw_index++) { >> + u32 *data = gmu->gpu_ib_votes[bw_index]; >> + u32 bw = gmu->gpu_bw_table[bw_index]; >> + >> + /* Calculations loosely copied from bcm_aggregate() & tcs_cmd_gen() */ >> + for (bcm_index = 0; bcm_index < bcm_count; bcm_index++) { >> + bool commit = false; >> + u64 peak, vote; >> + u16 width; >> + u32 unit; >> + >> + /* Skip unconfigured BCM */ >> + if (!bcm_data[bcm_index]) >> + continue; >> + >> + if (bcm_index == bcm_count - 1 || >> + (bcm_data[bcm_index + 1] && >> + bcm_data[bcm_index]->vcd != bcm_data[bcm_index + 1]->vcd)) >> + commit = true; >> + >> + if (!bw) { >> + data[bcm_index] = BCM_TCS_CMD(commit, false, 0, 0); >> + continue; >> + } >> + >> + if (info->bcms[bcm_index].fixed) { >> + u32 perfmode = 0; >> + >> + if (bw >= info->bcms[bcm_index].perfmode_bw) >> + perfmode = info->bcms[bcm_index].perfmode; >> + >> + data[bcm_index] = BCM_TCS_CMD(commit, true, 0, perfmode); >> + continue; >> + } >> + >> + /* Multiply the bandwidth by the width of the connection */ >> + width = le16_to_cpu(bcm_data[bcm_index]->width); >> + peak = bcm_div((u64)bw * width, info->bcms[bcm_index].buswidth); >> + >> + /* Input bandwidth value is in KBps, scale the value to BCM unit */ >> + unit = le32_to_cpu(bcm_data[bcm_index]->unit); >> + vote = bcm_div(peak * 1000ULL, unit); >> + >> + if (vote > BCM_TCS_CMD_VOTE_MASK) >> + vote = BCM_TCS_CMD_VOTE_MASK; > > use clamp()?
Yep, I think I could replace bcm_div with clamp
> >> + >> + data[bcm_index] = BCM_TCS_CMD(commit, true, vote, vote); >> + } >> + } >> + >> + /* Generate AB votes which are a quantitized bandwidth value */ >> + for (bw_index = 0; bw_index < gmu->nr_gpu_bws; bw_index++) { >> + u64 tmp; >> + >> + /* >> + * 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 = gmu->gpu_bw_table[bw_index] * MAX_AB_VOTE; >> + >> + /* Divide by the maximum bandwidth to get a quantized value */ >> + gmu->gpu_ab_votes[bw_index] = >> + bcm_div(tmp, gmu->gpu_bw_table[gmu->nr_gpu_bws - 1]); >> + } > > So I suppose you are trying to vote AB equal to IB. Aggregation logic > for both are different. So this will make DDR scale very aggressively. A > more reasonable approach would be to vote a % of IB vote (25%?). Ideally > we should measure GPU's bandwidth usage and vote that if you are really > concerned about stability issues. IB is just a floor vote, GPU can > generate way higher traffic.
I think this should be optimized better in a different patchset, so I would like to make the simplest vote possible here to retain functionnality.
So if I understand I should divide this vote value by 4 ? Downstram uses 25% by default when no AB was calculated, but what does that mean exactly ?
Is there a counter somewhere to measure the GPU traffic ?
> >> + >> + return 0; >> +} >> + >> /* Return the 'arc-level' for the given frequency */ >> static unsigned int a6xx_gmu_get_arc_level(struct device *dev, >> unsigned long freq) >> @@ -1390,12 +1516,15 @@ static int a6xx_gmu_rpmh_arc_votes_init(struct device *dev, u32 *votes, >> * The GMU votes with the RPMh for itself and on behalf of the GPU but we need >> * to construct the list of votes on the CPU and send it over. Query the RPMh >> * voltage levels and build the votes >> + * The GMU can also vote for DDR interconnects, use the OPP bandwidth entries >> + * and BCM parameters to build the votes. >> */ >> >> static int a6xx_gmu_rpmh_votes_init(struct a6xx_gmu *gmu) >> { >> struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu); >> struct adreno_gpu *adreno_gpu = &a6xx_gpu->base; >> + const struct a6xx_info *info = adreno_gpu->info->a6xx; >> struct msm_gpu *gpu = &adreno_gpu->base; >> int ret; >> >> @@ -1407,6 +1536,10 @@ static int a6xx_gmu_rpmh_votes_init(struct a6xx_gmu *gmu) >> ret |= a6xx_gmu_rpmh_arc_votes_init(gmu->dev, gmu->cx_arc_votes, >> gmu->gmu_freqs, gmu->nr_gmu_freqs, "cx.lvl"); >> >> + /* Build the interconnect votes */ >> + if (info->bcms && gmu->nr_gpu_bws > 1) >> + ret |= a6xx_gmu_rpmh_bw_votes_init(info, gmu); >> + >> return ret; >> } >> >> @@ -1442,10 +1575,43 @@ static int a6xx_gmu_build_freq_table(struct device *dev, unsigned long *freqs, >> return index; >> } >> >> +static int a6xx_gmu_build_bw_table(struct device *dev, unsigned long *bandwidths, >> + u32 size) >> +{ >> + int count = dev_pm_opp_get_opp_count(dev); > > I am less concerned about this now since you are not voting real AB BW.
Sorry I don't understand
Thanks, Neil
> > -Akhil. > >> + struct dev_pm_opp *opp; >> + int i, index = 0; >> + unsigned int bandwidth = 1; >> + >> + /* >> + * The OPP table doesn't contain the "off" bandwidth level so we need to >> + * add 1 to the table size to account for it >> + */ >> + >> + if (WARN(count + 1 > size, >> + "The GMU bandwidth table is being truncated\n")) >> + count = size - 1; >> + >> + /* Set the "off" bandwidth */ >> + bandwidths[index++] = 0; >> + >> + for (i = 0; i < count; i++) { >> + opp = dev_pm_opp_find_bw_ceil(dev, &bandwidth, 0); >> + if (IS_ERR(opp)) >> + break; >> + >> + dev_pm_opp_put(opp); >> + bandwidths[index++] = bandwidth++; >> + } >> + >> + return index; >> +} >> + >> static int a6xx_gmu_pwrlevels_probe(struct a6xx_gmu *gmu) >> { >> struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu); >> struct adreno_gpu *adreno_gpu = &a6xx_gpu->base; >> + const struct a6xx_info *info = adreno_gpu->info->a6xx; >> struct msm_gpu *gpu = &adreno_gpu->base; >> >> int ret = 0; >> @@ -1472,6 +1638,14 @@ static int a6xx_gmu_pwrlevels_probe(struct a6xx_gmu *gmu) >> >> gmu->current_perf_index = gmu->nr_gpu_freqs - 1; >> >> + /* >> + * The GMU also handles GPU Interconnect Votes so build a list >> + * of DDR bandwidths from the GPU OPP table >> + */ >> + if (info->bcms) >> + gmu->nr_gpu_bws = a6xx_gmu_build_bw_table(&gpu->pdev->dev, >> + gmu->gpu_bw_table, ARRAY_SIZE(gmu->gpu_bw_table)); >> + >> /* Build the list of RPMh votes that we'll send to the GMU */ >> return a6xx_gmu_rpmh_votes_init(gmu); >> } >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >> index 88f18ea6a38a08b5b171709e5020010947a5d347..bdfc106cb3a578c90d7cd84f7d4fe228d761a994 100644 >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h >> @@ -21,6 +21,15 @@ struct a6xx_gmu_bo { >> >> #define GMU_MAX_GX_FREQS 16 >> #define GMU_MAX_CX_FREQS 4 >> +#define GMU_MAX_BCMS 3 >> + >> +struct a6xx_bcm { >> + char *name; >> + unsigned int buswidth; >> + bool fixed; >> + unsigned int perfmode; >> + unsigned int perfmode_bw; >> +}; >> >> /* >> * These define the different GMU wake up options - these define how both the >> @@ -85,6 +94,11 @@ struct a6xx_gmu { >> unsigned long gpu_freqs[GMU_MAX_GX_FREQS]; >> u32 gx_arc_votes[GMU_MAX_GX_FREQS]; >> >> + int nr_gpu_bws; >> + unsigned long gpu_bw_table[GMU_MAX_GX_FREQS]; >> + u32 gpu_ib_votes[GMU_MAX_GX_FREQS][GMU_MAX_BCMS]; >> + u16 gpu_ab_votes[GMU_MAX_GX_FREQS]; >> + >> int nr_gmu_freqs; >> unsigned long gmu_freqs[GMU_MAX_CX_FREQS]; >> u32 cx_arc_votes[GMU_MAX_CX_FREQS]; >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h >> index 4aceffb6aae89c781facc2a6e4a82b20b341b6cb..9201a53dd341bf432923ffb44947e015208a3d02 100644 >> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h >> @@ -44,6 +44,7 @@ struct a6xx_info { >> u32 gmu_chipid; >> u32 gmu_cgc_mode; >> u32 prim_fifo_threshold; >> + const struct a6xx_bcm *bcms; >> }; >> >> struct a6xx_gpu { >> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h >> index 528110169398f69f16443a29a1594d19c36fb595..52ba4a07d7b9a709289acd244a751ace9bdaab5d 100644 >> --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.h >> +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.h >> @@ -173,6 +173,11 @@ struct a6xx_hfi_gx_bw_perf_vote_cmd { >> u32 bw; >> }; >> >> +#define AB_VOTE_MASK GENMASK(31, 16) >> +#define MAX_AB_VOTE (FIELD_MAX(AB_VOTE_MASK) - 1) >> +#define AB_VOTE(vote) FIELD_PREP(AB_VOTE_MASK, (vote)) >> +#define AB_VOTE_ENABLE BIT(8) >> + >> #define HFI_H2F_MSG_PREPARE_SLUMBER 33 >> >> struct a6xx_hfi_prep_slumber_cmd { >> >
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