On 11.12.2024 9:29 AM, 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 other side 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 vote will be calculated later when setting the frequency.
>
> The vote array will then be used to dynamically generate the GMU
> bw_table sent during the GMU power-up.
>
> Reviewed-by: Akhil P Oommen <quic_akhi...@quicinc.com>
> Signed-off-by: Neil Armstrong <neil.armstr...@linaro.org>
> ---
> drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 144
> ++++++++++++++++++++++++++++++++++
> drivers/gpu/drm/msm/adreno/a6xx_gmu.h | 13 +++
> drivers/gpu/drm/msm/adreno/a6xx_gpu.h | 1 +
> 3 files changed, 158 insertions(+)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
> index
> 14db7376c712d19446b38152e480bd5a1e0a5198..36696d372a42a27b26a018b19e73bc6d8a4a5235
> 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 +1288,101 @@ 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;
> +};
No. This is a direct copypasta of drivers/interconnect/qcom/icc-rpmh.h
You cannot just randomly duplicate things..
Move it out to a shared header in include/ (and remove the duplicate from
clk-rpmh.c while at it)
I'd also really prefer if you took
drivers/interconnect/qcom/bcm-voter.c : tcs_list_gen()
and abstracted it to operate on struct bcm_db with any additional
required parameters passed as arguments.. Still left some comments
on this version if you decide to go with it
> +
> +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;
You already checked that from the caller
> +
> + /* 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;
Unconfigured doesn't really fit here.. Maybe just mention the list is NULL
-terminated
> +
> + 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;
If this condition ever happens, it'll be impossible to track down,
please add an err message
> +
> + ++bcm_count;
I've heard somewhere that prefixed increments are discouraged for
"reasons" and my OCD would like to support that
> + }
> +
> + /* 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;
> + u32 vote;
> +
> + /* Skip unconfigured BCM */
> + if (!bcm_data[bcm_index])
> + continue;
I don't see how this is useful here
> +
> + 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) {
You may want to take a pointer to info->bcms[bcm_index]
> + 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 */
> + peak = (u64)bw *
> le16_to_cpu(bcm_data[bcm_index]->width);
> + do_div(peak, info->bcms[bcm_index].buswidth);
> +
> + /* Input bandwidth value is in KBps, scale the value to
> BCM unit */
> + peak *= 1000ULL;
I don't think this needs to be ULL since the other argument is an u64
> + do_div(peak, le32_to_cpu(bcm_data[bcm_index]->unit));
> +
> + vote = clamp(peak, 1, BCM_TCS_CMD_VOTE_MASK);
> +
> + data[bcm_index] = BCM_TCS_CMD(commit, true, vote, vote);
x is the avg vote, y is the peak vote
Just noting down for my future self I guess, a6xx sets ab=0,
a7xx sets ab=ib like you did here
Konrad
