On Fri, Nov 15, 2024 at 10:09:44AM +0100, Neil Armstrong wrote:
> On 15/11/2024 08:20, Dmitry Baryshkov wrote:
> > On Wed, Nov 13, 2024 at 04:48:29PM +0100, Neil Armstrong wrote:
> > > The Adreno GMU 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.
> > >
> > > In order to get the vote values to be used by the GPU Management
> > > Unit (GMU), we need to parse all the possible OPP Bandwidths and
> > > create a vote value to be send to the appropriate Bus Control
> > > Modules (BCMs) declared in the GPU info struct.
> > >
> > > The vote array will be used to dynamically generate the GMU bw_table
> > > sent during the GMU power-up.
> > >
> > > Signed-off-by: Neil Armstrong <neil.armstr...@linaro.org>
> > > ---
> > > drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 163
> > > ++++++++++++++++++++++++++++++++++
> > > drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 12 +++
> > > drivers/gpu/drm/msm/adreno/a6xx_gpu.h | 1 +
> > > 3 files changed, 176 insertions(+)
> > >
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> > > b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> > > index
> > > 14db7376c712d19446b38152e480bd5a1e0a5198..504a7c5d5a9df4c787951f2ae3a69d566d205ad5
> > > 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 +1288,119 @@ static int a6xx_gmu_memory_probe(struct a6xx_gmu
> > > *gmu)
> > > return 0;
> > > }
> > > +struct a6xx_bcm_data {
> > > + u32 buswidth;
> > > + unsigned int unit;
> > > + unsigned int width;
> >
> > In bits?
> >
> > > + unsigned int vcd;
> >
> > What is this?
>
> I'll also copy the icc-rpmh.h doc associated with those fields
Yes, please please provide some kerneldoc for the srtuct.
>
> >
> > > + bool fixed;
> >
> > What does it mean?
>
> I took it from downstream, but it's the same as qcom_icc_bcm enable_mask
> instead here the mask depends on the platform and OPP, this is why I
> specified it in perfmode.
>
> >
> > > + unsigned int perfmode;
> > > + unsigned int perfmode_bw;
> > > +};
> > > +
> > > +struct bcm_db {
> > > + __le32 unit;
> > > + __le16 width;
> > > + u8 vcd;
> > > + u8 reserved;
> > > +};
> > > +
> > > +static int a6xx_gmu_rpmh_get_bcm_data(const struct a6xx_bcm *bcm,
> > > + struct a6xx_bcm_data *bcm_data)
> >
> > Is there a reason to copy CMD DB and BCM data to the interim
> > representation instead of using those directly?
>
> I guess I can keep bcm_db & a6xx_bcm as-is and do the _to_cpu() in-place.
I think that makes sense.
>
> >
> > > +{
> > > + const struct bcm_db *data;
> > > + size_t count;
> > > +
> > > + data = cmd_db_read_aux_data(bcm->name, &count);
> > > + if (IS_ERR(data))
> > > + return PTR_ERR(data);
> > > +
> > > + if (!count)
> > > + return -EINVAL;
> > > +
> > > + bcm_data->unit = le32_to_cpu(data->unit);
> > > + bcm_data->width = le16_to_cpu(data->width);
> > > + bcm_data->vcd = data->vcd;
> > > + bcm_data->fixed = bcm->fixed;
> > > + bcm_data->perfmode = bcm->perfmode;
> > > + bcm_data->perfmode_bw = bcm->perfmode_bw;
> > > + bcm_data->buswidth = bcm->buswidth;
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static void a6xx_gmu_rpmh_calc_bw_vote(struct a6xx_bcm_data *bcms,
> > > + int count, u32 bw, u32 *data)
> > > +{
> > > + int i;
> > > +
> > > + for (i = 0; i < count; i++) {
> > > + bool valid = true;
> > > + bool commit = false;
> > > + u64 peak, y;
> > > +
> > > + if (i == count - 1 || bcms[i].vcd != bcms[i + 1].vcd)
> > > + commit = true;
> > > +
> > > + if (bcms[i].fixed) {
> > > + if (!bw)
> > > + data[i] = BCM_TCS_CMD(commit, false, 0x0, 0x0);
> > > + else
> > > + data[i] = BCM_TCS_CMD(commit, true, 0x0,
> > > + bw >= bcms[i].perfmode_bw ?
> > > + bcms[i].perfmode : 0x0);
> > > + continue;
> > > + }
> > > +
> > > + /* Multiple the bandwidth by the width of the connection */
> >
> > ... and divide by the bus width. However it's not clear why you are
> > multiplying bandwidth (bits or bytes per second) with the width
> > (probably also bits?). Or is it not a width but the number of paths
> > between units?
>
> So this is basically the same as in bcm_agregate:
> https://elixir.bootlin.com/linux/v6.12-rc6/source/drivers/interconnect/qcom/bcm-voter.c#L91
>
> Just done slightly differently since we don't aggregate stuff but we want
> to set the bandwidth directly here from the GMU.
I see. And width comes from the CMD DB too.
>
> >
> > > + peak = (u64)bw * bcms[i].width;
> > > + do_div(peak, bcms[i].buswidth);
> > > +
> > > + /* Input bandwidth value is in KBps */
> >
> > Input or OPP / Interconnect?
>
> I don't see the point, it's the input of the function which directly comes
> from OPP which is in KBps
I meant is it about the calculated 'peak' value? Also it might be worth
adding something mult_frac_ull, using do_div() instead of usual
division.
> > > + y = peak * 1000ULL;
> > > + do_div(y, bcms[i].unit);
> > > +
> > > + /*
> > > + * If a bandwidth value was specified but the calculation ends
> > > + * rounding down to zero, set a minimum level
> > > + */
> > > + if (bw && y == 0)
> > > + y = 1;
> >
> > Is it a real usecase or just a safety net? If the bandwidth ends up
> > being very low, maybe we should warn the users about it?
>
> Probably a safety net, perhaps we could warn instead
>
> >
> > > +
> > > + y = min_t(u64, y, BCM_TCS_CMD_VOTE_MASK);
> > > + if (!y)
> > > + valid = false;
> >
> > This can probably be coupled with the previous condition.
>
> Yeah I should probably refactor it and just avoid doing the
> calculation if bw == 0.
>
> >
> > > +
> > > + data[i] = BCM_TCS_CMD(commit, valid, y, y);
> > > + }
> > > +}
> > > +
> > > +static int a6xx_gmu_rpmh_bw_votes_init(const struct a6xx_info *info,
> > > struct a6xx_gmu *gmu)
> > > +{
> > > + struct a6xx_bcm_data bcms[3];
> > > + unsigned int bcm_count = 0;
> > > + int ret, index;
> > > +
> > > + /* Retrieve BCM data from cmd-db and merge with a6xx_info bcm table */
> > > + for (index = 0; index < 3; index++) {
> >
> > Magic number 3.
> >
> > > + if (!info->bcm[index].name)
> > > + continue;
> > > +
> > > + ret = a6xx_gmu_rpmh_get_bcm_data(&info->bcm[index],
> > > &bcms[index]);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + ++bcm_count;
> > > + }
> > > +
> > > + /* Generate BCM votes values for each bandwidth & bcm */
> > > + for (index = 0; index < gmu->nr_gpu_bws; index++)
> > > + a6xx_gmu_rpmh_calc_bw_vote(bcms, bcm_count,
> > > gmu->gpu_bw_table[index],
> > > + gmu->gpu_bw_votes[index]);
> > > +
> > > + 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 +1504,15 @@ 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 +1524,10 @@ 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 (adreno_gpu->info->quirks & ADRENO_QUIRK_GMU_BW_VOTE)
> > > + ret |= a6xx_gmu_rpmh_bw_votes_init(info, gmu);
> > > +
> > > return ret;
> > > }
> > > @@ -1442,6 +1563,38 @@ 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);
> > > + 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);
> > > @@ -1472,6 +1625,16 @@ 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 (adreno_gpu->info->quirks & ADRENO_QUIRK_GMU_BW_VOTE)
> > > + gmu->nr_gpu_bws = a6xx_gmu_build_bw_table(&gpu->pdev->dev,
> > > + gmu->gpu_bw_table, ARRAY_SIZE(gmu->gpu_bw_table));
> > > +
> > > + gmu->current_perf_index = gmu->nr_gpu_freqs - 1;
> > > +
> > > /* 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
> > > b4a79f88ccf45cfe651c86d2a9da39541c5772b3..95c632d8987a517f067c48c61c6c06b9a4f61fc0
> > > 100644
> > > --- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
> > > +++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.h
> > > @@ -19,6 +19,14 @@ struct a6xx_gmu_bo {
> > > u64 iova;
> > > };
> > > +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
> > > * CPU and the GMU bring up the hardware
> > > @@ -82,6 +90,10 @@ struct a6xx_gmu {
> > > unsigned long gpu_freqs[16];
> > > u32 gx_arc_votes[16];
> > > + int nr_gpu_bws;
> > > + unsigned long gpu_bw_table[16];
> > > + u32 gpu_bw_votes[16][3];
> >
> > Is it is the same magic 16 as we have few lines above or is this 16 a
> > different magic 16? And also 3 is a pure dark secret.
>
> It's the same magic 16, since we use the same OPPs, the 3 is the actual
> number of BCMs we currently use, I wonder sure define should go, including
> the magic 16.
I think those defines can go to a6xx_gmu.h.
Also if the 16 is the same, should we define something like
struct a6xx_gmu_freq_something {
};
...
struct a6xx_gmu {
struct a6xx_gmu_freq_something bw_data[16];
};
Seeing repetitive field size always makes me think about such a change.
>
> >
> > > +
> > > int nr_gmu_freqs;
> > > unsigned long gmu_freqs[4];
> > > u32 cx_arc_votes[4];
> > > diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> > > b/drivers/gpu/drm/msm/adreno/a6xx_gpu.h
> > > index
> > > 4aceffb6aae89c781facc2a6e4a82b20b341b6cb..d779d700120cbd974ee87a67214739b1d85156e2
> > > 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 bcm[3];
> > > };
> > > struct a6xx_gpu {
> > >
> > > --
> > > 2.34.1
> > >
> >
>
--
With best wishes
Dmitry
