[PATCH v4 8/9] drm/msm/dpu: rework core_perf debugfs overrides
Abhinav Kumar
quic_abhinavk at quicinc.com
Wed Jan 15 19:51:20 UTC 2025
On 1/15/2025 12:41 AM, Dmitry Baryshkov wrote:
> On Tue, Jan 14, 2025 at 02:02:54PM -0800, Abhinav Kumar wrote:
>>
>>
>> On 1/5/2025 7:07 PM, Dmitry Baryshkov wrote:
>>> Currently debugfs provides separate 'modes' to override calculated
>>> MDP_CLK rate and interconnect bandwidth votes. Change that to allow
>>> overriding individual values (e.g. one can override just clock or just
>>> average bandwidth vote). The maximum values allowed for those entries by
>>> the platform can be read from the 'max_core_ab' and 'max_core_clk_rate'
>>> files in debugfs.
>>>
>>
>> Apart from the concern I highlighted in the previous patch, the only issue I
>> have with this is that, this went from a one step process of using the
>> "mode" this has become a two step one.
>>
>> There were essentially two modes we are talking about - "fixed" and
>> "minimum"
>>
>> With respect to "fixed" this is totally fine because this is preserving that
>> functionality because to be able to set the fixed mode the end user must
>> know what values they want to try anyway.
>>
>> With respect to "minimum" mode, is where this approach is not that great.
>> The end users of this can be non-display developers too such as our QA teams
>> who might want to perform a first level of triage on the issues and route it
>> accordingly. This is especially true for underruns and some performance lags
>> as well.
>>
>> If you really dont like the term "modes", to preserve the "minimum" mode,
>> how about just using a bool debugfs like "max_perf_params" which internally
>> maxes out the max MDP clock and ab/ib params.
>
> That's what I'm trying to avoid - having an extra debugfs file which
> overrides other files. It is much easier to work if there is no need to
> switch modes, it is easy to overlook it. I think it should be fine to
> use `cat max_foo > fix_foo` to override each of the params. After
> renaming the threshold_high to max_core_ab the names of the debugfs
> files match.
>
Its just a difference in interpretation IMO.
the "fixed" mode is trying to given an option to incrementally try and
see which value really works and also to see whether its the clock OR
the bandwidth which is making the difference. So individual control of
those.
The "max" mode is trying to see if even the max values of everything
cannot fix the problem. BTW, the max was maxing out BOTH the DPU clocks
and BW.
So this is not just 2 extra reads for the user but 3. (ab/ib/dpu_clk) if
we drop "max" and use "fixed" for max as well and even for that the user
has to refer the max DPU clock value.
>>
>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov at linaro.org>
>>> ---
>>> drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c | 87 +++------------------------
>>> drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h | 10 ---
>>> 2 files changed, 9 insertions(+), 88 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
>>> index 7ff3405c6867556a8dc776783b91f1da6c86ef3f..913eb4c01abe10c1ed84215fbbee50abd69e9317 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
>>> @@ -17,20 +17,6 @@
>>> #include "dpu_crtc.h"
>>> #include "dpu_core_perf.h"
>>> -/**
>>> - * enum dpu_perf_mode - performance tuning mode
>>> - * @DPU_PERF_MODE_NORMAL: performance controlled by user mode client
>>> - * @DPU_PERF_MODE_MINIMUM: performance bounded by minimum setting
>>> - * @DPU_PERF_MODE_FIXED: performance bounded by fixed setting
>>> - * @DPU_PERF_MODE_MAX: maximum value, used for error checking
>>> - */
>>> -enum dpu_perf_mode {
>>> - DPU_PERF_MODE_NORMAL,
>>> - DPU_PERF_MODE_MINIMUM,
>>> - DPU_PERF_MODE_FIXED,
>>> - DPU_PERF_MODE_MAX
>>> -};
>>> -
>>> /**
>>> * _dpu_core_perf_calc_bw() - to calculate BW per crtc
>>> * @perf_cfg: performance configuration
>>> @@ -215,18 +201,16 @@ static int _dpu_core_perf_crtc_update_bus(struct dpu_kms *kms,
>>> if (!kms->num_paths)
>>> return 0;
>>> - if (kms->perf.perf_tune.mode == DPU_PERF_MODE_MINIMUM) {
>>> - avg_bw = 0;
>>> - peak_bw = 0;
>>> - } else if (kms->perf.perf_tune.mode == DPU_PERF_MODE_FIXED) {
>>> + dpu_core_perf_aggregate(crtc->dev, dpu_crtc_get_client_type(crtc), &perf);
>>> +
>>> + avg_bw = div_u64(perf.bw_ctl, 1000); /*Bps_to_icc*/
>>> + peak_bw = perf.max_per_pipe_ib;
>>> +
>>> + if (kms->perf.fix_core_ab_vote)
>>> avg_bw = kms->perf.fix_core_ab_vote;
>>> - peak_bw = kms->perf.fix_core_ib_vote;
>>> - } else {
>>> - dpu_core_perf_aggregate(crtc->dev, dpu_crtc_get_client_type(crtc), &perf);
>>> - avg_bw = div_u64(perf.bw_ctl, 1000); /*Bps_to_icc*/
>>> - peak_bw = perf.max_per_pipe_ib;
>>> - }
>>> + if (kms->perf.fix_core_ib_vote)
>>> + peak_bw = kms->perf.fix_core_ib_vote;
>>> avg_bw /= kms->num_paths;
>>> @@ -275,12 +259,9 @@ static u64 _dpu_core_perf_get_core_clk_rate(struct dpu_kms *kms)
>>> struct drm_crtc *crtc;
>>> struct dpu_crtc_state *dpu_cstate;
>>> - if (kms->perf.perf_tune.mode == DPU_PERF_MODE_FIXED)
>>> + if (kms->perf.fix_core_clk_rate)
>>> return kms->perf.fix_core_clk_rate;
>>> - if (kms->perf.perf_tune.mode == DPU_PERF_MODE_MINIMUM)
>>> - return kms->perf.max_core_clk_rate;
>>> -
>>> clk_rate = 0;
>>> drm_for_each_crtc(crtc, kms->dev) {
>>> if (crtc->enabled) {
>>> @@ -396,54 +377,6 @@ int dpu_core_perf_crtc_update(struct drm_crtc *crtc,
>>> #ifdef CONFIG_DEBUG_FS
>>> -static ssize_t _dpu_core_perf_mode_write(struct file *file,
>>> - const char __user *user_buf, size_t count, loff_t *ppos)
>>> -{
>>> - struct dpu_core_perf *perf = file->private_data;
>>> - u32 perf_mode = 0;
>>> - int ret;
>>> -
>>> - ret = kstrtouint_from_user(user_buf, count, 0, &perf_mode);
>>> - if (ret)
>>> - return ret;
>>> -
>>> - if (perf_mode >= DPU_PERF_MODE_MAX)
>>> - return -EINVAL;
>>> -
>>> - if (perf_mode == DPU_PERF_MODE_FIXED) {
>>> - DRM_INFO("fix performance mode\n");
>>> - } else if (perf_mode == DPU_PERF_MODE_MINIMUM) {
>>> - /* run the driver with max clk and BW vote */
>>> - DRM_INFO("minimum performance mode\n");
>>> - } else if (perf_mode == DPU_PERF_MODE_NORMAL) {
>>> - /* reset the perf tune params to 0 */
>>> - DRM_INFO("normal performance mode\n");
>>> - }
>>> - perf->perf_tune.mode = perf_mode;
>>> -
>>> - return count;
>>> -}
>>> -
>>> -static ssize_t _dpu_core_perf_mode_read(struct file *file,
>>> - char __user *buff, size_t count, loff_t *ppos)
>>> -{
>>> - struct dpu_core_perf *perf = file->private_data;
>>> - int len;
>>> - char buf[128];
>>> -
>>> - len = scnprintf(buf, sizeof(buf),
>>> - "mode %d\n",
>>> - perf->perf_tune.mode);
>>> -
>>> - return simple_read_from_buffer(buff, count, ppos, buf, len);
>>> -}
>>> -
>>> -static const struct file_operations dpu_core_perf_mode_fops = {
>>> - .open = simple_open,
>>> - .read = _dpu_core_perf_mode_read,
>>> - .write = _dpu_core_perf_mode_write,
>>> -};
>>> -
>>> /**
>>> * dpu_core_perf_debugfs_init - initialize debugfs for core performance context
>>> * @dpu_kms: Pointer to the dpu_kms struct
>>> @@ -472,8 +405,6 @@ int dpu_core_perf_debugfs_init(struct dpu_kms *dpu_kms, struct dentry *parent)
>>> (u32 *)&perf->perf_cfg->min_llcc_ib);
>>> debugfs_create_u32("min_dram_ib", 0400, entry,
>>> (u32 *)&perf->perf_cfg->min_dram_ib);
>>> - debugfs_create_file("perf_mode", 0600, entry,
>>> - (u32 *)perf, &dpu_core_perf_mode_fops);
>>> debugfs_create_u64("fix_core_clk_rate", 0600, entry,
>>> &perf->fix_core_clk_rate);
>>> debugfs_create_u32("fix_core_ib_vote", 0600, entry,
>>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h
>>> index 5e07119c14c6a9ed3413d0eaddbd93df5cc3f79d..9d8516ca32d162b1e277ec88067e5c21abeb2017 100644
>>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h
>>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h
>>> @@ -24,20 +24,11 @@ struct dpu_core_perf_params {
>>> u64 core_clk_rate;
>>> };
>>> -/**
>>> - * struct dpu_core_perf_tune - definition of performance tuning control
>>> - * @mode: performance mode
>>> - */
>>> -struct dpu_core_perf_tune {
>>> - u32 mode;
>>> -};
>>> -
>>> /**
>>> * struct dpu_core_perf - definition of core performance context
>>> * @perf_cfg: Platform-specific performance configuration
>>> * @core_clk_rate: current core clock rate
>>> * @max_core_clk_rate: maximum allowable core clock rate
>>> - * @perf_tune: debug control for performance tuning
>>> * @enable_bw_release: debug control for bandwidth release
>>> * @fix_core_clk_rate: fixed core clock request in Hz used in mode 2
>>> * @fix_core_ib_vote: fixed core ib vote in bps used in mode 2
>>> @@ -47,7 +38,6 @@ struct dpu_core_perf {
>>> const struct dpu_perf_cfg *perf_cfg;
>>> u64 core_clk_rate;
>>> u64 max_core_clk_rate;
>>> - struct dpu_core_perf_tune perf_tune;
>>> u32 enable_bw_release;
>>> u64 fix_core_clk_rate;
>>> u32 fix_core_ib_vote;
>>>
>
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