RE: [PATCH 4/4] drm/msm/disp/dpu1: add color management support for the crtc

[Kalyan Thota]

>-----Original Message-----
>From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
>Sent: Wednesday, November 9, 2022 6:02 PM
>To: Kalyan Thota (QUIC) <quic_kalyant@xxxxxxxxxxx>; dri-
>devel@xxxxxxxxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx;
>freedreno@xxxxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx
>Cc: linux-kernel@xxxxxxxxxxxxxxx; robdclark@xxxxxxxxxxxx;
>dianders@xxxxxxxxxxxx; swboyd@xxxxxxxxxxxx; Vinod Polimera (QUIC)
><quic_vpolimer@xxxxxxxxxxx>; Abhinav Kumar (QUIC)
><quic_abhinavk@xxxxxxxxxxx>
>Subject: Re: [PATCH 4/4] drm/msm/disp/dpu1: add color management support
>for the crtc
>
>WARNING: This email originated from outside of Qualcomm. Please be wary of
>any links or attachments, and do not enable macros.
>
>On 09/11/2022 15:16, Kalyan Thota wrote:
>> Add color management support for the crtc provided there are enough
>> dspps that can be allocated from the catalogue
>>
>> Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    | 15 ++++++--
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h    |  6 ++++
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 11 +++---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     | 53
>+++++++++++++++++++++++++++++
>>   4 files changed, 77 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> index 4170fbe..6bd3a64 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> @@ -18,9 +18,11 @@
>>   #include <drm/drm_flip_work.h>
>>   #include <drm/drm_framebuffer.h>
>>   #include <drm/drm_mode.h>
>> +#include <drm/drm_mode_object.h>
>>   #include <drm/drm_probe_helper.h>
>>   #include <drm/drm_rect.h>
>>   #include <drm/drm_vblank.h>
>> +#include "../../../drm_crtc_internal.h"
>
>If it's internal, it is not supposed to be used by other parties, including the msm
>drm. At least a comment why you are including this file would be helpful.
>
This header file was included to make use of " drm_mode_obj_find_prop_id" function from DRM framework.
Should I add a comment near function definition ?
>>
>>   #include "dpu_kms.h"
>>   #include "dpu_hw_lm.h"
>> @@ -553,6 +555,17 @@ static void _dpu_crtc_complete_flip(struct drm_crtc
>*crtc)
>>       spin_unlock_irqrestore(&dev->event_lock, flags);
>>   }
>>
>> +bool dpu_crtc_has_color_enabled(struct drm_crtc *crtc) {
>> +     u32 ctm_id = crtc->dev->mode_config.ctm_property->base.id;
>> +     u32 gamma_id = crtc->dev->mode_config.gamma_lut_property->base.id;
>> +     u32 degamma_id =
>> +crtc->dev->mode_config.degamma_lut_property->base.id;
>> +
>> +     return !!(drm_mode_obj_find_prop_id(&crtc->base, ctm_id) ||
>> +                drm_mode_obj_find_prop_id(&crtc->base, gamma_id) ||
>> +                drm_mode_obj_find_prop_id(&crtc->base, degamma_id));
>> +}
>> +
>>   enum dpu_intf_mode dpu_crtc_get_intf_mode(struct drm_crtc *crtc)
>>   {
>>       struct drm_encoder *encoder;
>> @@ -1604,8 +1617,6 @@ struct drm_crtc *dpu_crtc_init(struct drm_device
>> *dev, struct drm_plane *plane,
>>
>>       drm_crtc_helper_add(crtc, &dpu_crtc_helper_funcs);
>>
>> -     drm_crtc_enable_color_mgmt(crtc, 0, true, 0);
>> -
>>       /* save user friendly CRTC name for later */
>>       snprintf(dpu_crtc->name, DPU_CRTC_NAME_SIZE, "crtc%u",
>> crtc->base.id);
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> index 539b68b..8bac395 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> @@ -300,4 +300,10 @@ static inline enum dpu_crtc_client_type
>dpu_crtc_get_client_type(
>>       return crtc && crtc->state ? RT_CLIENT : NRT_CLIENT;
>>   }
>>
>> +/**
>> + * dpu_crtc_has_color_enabled - check if the crtc has color
>> +management enabled
>> + * @crtc: Pointer to drm crtc object
>> + */
>> +bool dpu_crtc_has_color_enabled(struct drm_crtc *crtc);
>> +
>>   #endif /* _DPU_CRTC_H_ */
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index 4c56a16..ebc3f25 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -545,7 +545,8 @@ bool dpu_encoder_use_dsc_merge(struct drm_encoder
>*drm_enc)
>>   static struct msm_display_topology dpu_encoder_get_topology(
>>                       struct dpu_encoder_virt *dpu_enc,
>>                       struct dpu_kms *dpu_kms,
>> -                     struct drm_display_mode *mode)
>> +                     struct drm_display_mode *mode,
>> +                     struct drm_crtc *crtc)
>>   {
>>       struct msm_display_topology topology = {0};
>>       int i, intf_count = 0;
>> @@ -573,11 +574,9 @@ static struct msm_display_topology
>dpu_encoder_get_topology(
>>       else
>>               topology.num_lm = (mode->hdisplay > MAX_HDISPLAY_SPLIT)
>> ? 2 : 1;
>>
>> -     if (dpu_enc->disp_info.intf_type == DRM_MODE_ENCODER_DSI) {
>> -             if (dpu_kms->catalog->dspp &&
>> -                     (dpu_kms->catalog->dspp_count >= topology.num_lm))
>> +     if (dpu_crtc_has_color_enabled(crtc) &&
>> +             (dpu_kms->catalog->dspp_count >= topology.num_lm))
>
>See the comment to the previous patch. It still applies here.
>
>>                       topology.num_dspp = topology.num_lm;
>> -     }
>>
>>       topology.num_enc = 0;
>>       topology.num_intf = intf_count;
>> @@ -643,7 +642,7 @@ static int dpu_encoder_virt_atomic_check(
>>               }
>>       }
>>
>> -     topology = dpu_encoder_get_topology(dpu_enc, dpu_kms, adj_mode);
>> +     topology = dpu_encoder_get_topology(dpu_enc, dpu_kms, adj_mode,
>> + crtc_state->crtc);
>>
>>       /* Reserve dynamic resources now. */
>>       if (!ret) {
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> index 552a89c..47a73fa 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> @@ -13,6 +13,7 @@
>>   #include <linux/dma-buf.h>
>>   #include <linux/of_irq.h>
>>   #include <linux/pm_opp.h>
>> +#include <linux/bitops.h>
>>
>>   #include <drm/drm_crtc.h>
>>   #include <drm/drm_file.h>
>> @@ -537,6 +538,44 @@ static void dpu_kms_wait_flush(struct msm_kms
>*kms, unsigned crtc_mask)
>>               dpu_kms_wait_for_commit_done(kms, crtc);
>>   }
>>
>> +/**
>> + * _dpu_kms_possible_dspps - Evaluate how many dspps pairs can be
>facilitated
>> +                             to enable color features for crtcs.
>> + * @dpu_kms:    Pointer to dpu kms structure
>> + * Returns:     count of dspp pairs
>> + *
>> + * Baring single entry, if atleast 2 dspps are available in the
>> +catalogue,
>> + * then color can be enabled for that crtc  */ static inline u32
>> +_dpu_kms_possible_dspps(struct dpu_kms *dpu_kms) {
>> +
>> +     u32 num_dspps = dpu_kms->catalog->dspp_count;
>> +
>> +     if (num_dspps > 1)
>> +             num_dspps =
>> +                     !(num_dspps % 2) ? num_dspps / 2 : (num_dspps -
>> + 1) / 2;
>
>Ugh. No. Please spell this clearly rather than using nice math and ternary
>operators:
>
>if (num_dspps <= 1)
>   return num_dspps;
>else
>   return num_dspps / 2;
>
>You see, if num_dspps %2 ! =0, then num_dspps / 2 == (num_dspps_2 - 1) / 2.
>
>
>> +
>> +     return num_dspps;
>> +}
>> +
>> +static u32 _dpu_kms_attach_color(struct drm_device *dev, u32 enc_mask,
>> +                                             u32 num_dspps) {
>> +     struct drm_encoder *encoder;
>> +     struct drm_crtc *crtc;
>> +
>> +     drm_for_each_encoder_mask(encoder, dev, enc_mask) {
>> +             crtc = drm_crtc_from_index(dev, ffs(encoder->possible_crtcs) - 1);
>> +             if (num_dspps && crtc) {
>> +                     drm_crtc_enable_color_mgmt(crtc, 0, true, 0);
>> +                     num_dspps--;
>
>Please.  You can do this at the time you create the crtc. It would be much simpler.
>
>> +             }
>> +     }
>> +
>> +     return num_dspps;
>> +}
>> +
>>   static int _dpu_kms_initialize_dsi(struct drm_device *dev,
>>                                   struct msm_drm_private *priv,
>>                                   struct dpu_kms *dpu_kms) @@ -747,6
>> +786,8 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
>>
>>       int primary_planes_idx = 0, cursor_planes_idx = 0, i, ret;
>>       int max_crtc_count;
>> +     u32 num_dspps, primary_enc_mask = 0, external_enc_mask = 0;
>> +
>>       dev = dpu_kms->dev;
>>       priv = dev->dev_private;
>>       catalog = dpu_kms->catalog;
>> @@ -796,6 +837,7 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms
>*dpu_kms)
>>       }
>>
>>       max_crtc_count = min(max_crtc_count, primary_planes_idx);
>> +     num_dspps = _dpu_kms_possible_dspps(dpu_kms);
>>
>>       /* Create one CRTC per encoder */
>>       encoder = list_first_entry(&(dev)->mode_config.encoder_list,
>> @@ -808,9 +850,20 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms
>*dpu_kms)
>>               }
>>               priv->crtcs[priv->num_crtcs++] = crtc;
>>               encoder->possible_crtcs = 1 << drm_crtc_index(crtc);
>> +
>> +             if (!dpu_encoder_is_external(encoder) &&
>> +                     !dpu_encoder_is_virtual(encoder))
>
>if (dpu_encoder_internal_output(encoder))
>
>> +                     primary_enc_mask |= drm_encoder_mask(encoder);
>> +             else if (dpu_encoder_is_external(encoder))
>> +                     external_enc_mask |= drm_encoder_mask(encoder);
>> +
>>               encoder = list_next_entry(encoder, head);
>>       }
>>
>> +     /* Prefer Primary encoders in registering for color support */
>> +     num_dspps = _dpu_kms_attach_color(dev, primary_enc_mask,
>num_dspps);
>> +     num_dspps = _dpu_kms_attach_color(dev, external_enc_mask,
>> + num_dspps);
>> +
>>       return 0;
>>   }
>>
>
>--
>With best wishes
>Dmitry