Re: [PATCH] drm/msm/dpu: Filter modes based on adjusted mode clock

[Abhinav Kumar <quic_abhinavk@quicinc.com>]

On 12/12/2024 5:05 PM, Dmitry Baryshkov wrote:
> On Thu, Dec 12, 2024 at 11:11:54AM -0800, Jessica Zhang wrote:
>> Filter out modes that have a clock rate greater than the max core clock
>> rate when adjusted for the perf clock factor
>>
>> This is especially important for chipsets such as QCS615 that have lower
>> limits for the MDP max core clock.
>>
>> Since the core CRTC clock is at least the mode clock (adjusted for the
>> perf clock factor) [1], the modes supported by the driver should be less
>> than the max core clock rate.
>>
>> [1] https://elixir.bootlin.com/linux/v6.12.4/source/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c#L83
>>
>> Signed-off-by: Jessica Zhang <quic_jesszhan@quicinc.com>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c | 29 +++++++++++++++++++--------
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h |  3 +++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c      | 12 +++++++++++
>>   3 files changed, 36 insertions(+), 8 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 6f0a37f954fe8797a4e3a34e7876a93d5e477642..0afd7c81981c722a1a9176062250c418255fe6d0 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.c
>> @@ -31,6 +31,26 @@ enum dpu_perf_mode {
>>   	DPU_PERF_MODE_MAX
>>   };
>>   
>> +/**
>> + * dpu_core_perf_adjusted_crtc_clk - Adjust given crtc clock rate according to
> 
> Nit: CRTC (here and further)
> 
>> + *   the perf clock factor.
>> + * @crtc_clk_rate - Unadjusted crtc clock rate
>> + * @perf_cfg: performance configuration
>> + */
>> +u64 dpu_core_perf_adjusted_crtc_clk(u64 crtc_clk_rate,
>> +				    const struct dpu_perf_cfg *perf_cfg)
> 
> It's not just the CRTC clocks
> 

Do you mean we should use adjusted mode clock here?

>> +{
>> +	u32 clk_factor;
>> +
>> +	clk_factor = perf_cfg->clk_inefficiency_factor;
>> +	if (clk_factor) {
>> +		crtc_clk_rate *= clk_factor;
>> +		do_div(crtc_clk_rate, 100);
>> +	}
>> +
>> +	return crtc_clk_rate;
>> +}
>> +
>>   /**
>>    * _dpu_core_perf_calc_bw() - to calculate BW per crtc
>>    * @perf_cfg: performance configuration
>> @@ -76,7 +96,6 @@ static u64 _dpu_core_perf_calc_clk(const struct dpu_perf_cfg *perf_cfg,
>>   	struct dpu_plane_state *pstate;
>>   	struct drm_display_mode *mode;
>>   	u64 crtc_clk;
> 
> While you are at it, could you please also add a patch, replacing height
> * vidth * vrefresh with mode->clock * 1000? The former one has limited
> precision.
> 
>> -	u32 clk_factor;
>>   
>>   	mode = &state->adjusted_mode;
>>   
>> @@ -90,13 +109,7 @@ static u64 _dpu_core_perf_calc_clk(const struct dpu_perf_cfg *perf_cfg,
>>   		crtc_clk = max(pstate->plane_clk, crtc_clk);
>>   	}
> 
> This function calculates crtc_clk as max(plane_clk, crtc_clk). Shouldn't
> we also reject the atomic_state if for any of the planes the corrected
> clock is lower than max_core_clk_rate
> 

You mean higher than max_core_clk_rate? If so, yes we can fix that up.

>>   
>> -	clk_factor = perf_cfg->clk_inefficiency_factor;
>> -	if (clk_factor) {
>> -		crtc_clk *= clk_factor;
>> -		do_div(crtc_clk, 100);
>> -	}
>> -
>> -	return crtc_clk;
>> +	return dpu_core_perf_adjusted_crtc_clk(crtc_clk, perf_cfg);
>>   }
>>   
>>   static struct dpu_kms *_dpu_crtc_get_kms(struct drm_crtc *crtc)
>> 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 451bf8021114d9d4a2dfdbb81ed4150fc559c681..c3bcd567cdfb66647c83682d1feedd69e33f0680 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_core_perf.h
>> @@ -54,6 +54,9 @@ struct dpu_core_perf {
>>   	u64 fix_core_ab_vote;
>>   };
>>   
>> +u64 dpu_core_perf_adjusted_crtc_clk(u64 clk_rate,
>> +				    const struct dpu_perf_cfg *perf_cfg);
>> +
>>   int dpu_core_perf_crtc_check(struct drm_crtc *crtc,
>>   		struct drm_crtc_state *state);
>>   
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> index ad3462476a143ec01a3b8817a2c85b0f50435a9e..cd7b84ab57a7526948c2beb7c5cefdddcbe4f6d9 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> @@ -1257,6 +1257,7 @@ static enum drm_mode_status dpu_crtc_mode_valid(struct drm_crtc *crtc,
>>   						const struct drm_display_mode *mode)
>>   {
>>   	struct dpu_kms *dpu_kms = _dpu_crtc_get_kms(crtc);
>> +	u64 adjusted_mode_clk;
>>   
>>   	/* if there is no 3d_mux block we cannot merge LMs so we cannot
>>   	 * split the large layer into 2 LMs, filter out such modes
>> @@ -1264,6 +1265,17 @@ static enum drm_mode_status dpu_crtc_mode_valid(struct drm_crtc *crtc,
>>   	if (!dpu_kms->catalog->caps->has_3d_merge &&
>>   	    mode->hdisplay > dpu_kms->catalog->caps->max_mixer_width)
>>   		return MODE_BAD_HVALUE;
>> +
>> +	adjusted_mode_clk = dpu_core_perf_adjusted_crtc_clk(mode->clock,
>> +							    dpu_kms->perf.perf_cfg);
>> +
>> +	/*
>> +	 * The given mode, adjusted for the perf clock factor, should not exceed
>> +	 * the max core clock rate
>> +	 */
>> +	if (adjusted_mode_clk > dpu_kms->perf.max_core_clk_rate / 1000)
>> +		return MODE_CLOCK_HIGH;
>> +
>>   	/*
>>   	 * max crtc width is equal to the max mixer width * 2 and max height is 4K
>>   	 */
>>
>> ---
>> base-commit: 423c1c96d6b2d3bb35072e33a5fdd8db6d2c0a74
>> change-id: 20241212-filter-mode-clock-8cb2e769f05b
>>
>> Best regards,
>> -- 
>> Jessica Zhang <quic_jesszhan@quicinc.com>
>>
>