RE: [v1] drm/msm/disp/dpu1: add color management support for the crtc

[Kalyan Thota]

>-----Original Message-----
>From: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
>Sent: Saturday, November 12, 2022 4:13 AM
>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: [v1] 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 11/11/2022 16:57, Kalyan Thota wrote:
>> Add color management support for the crtc provided there are enough
>> dspps that can be allocated from the catalogue.
>>
>> Changes in v1:
>> - cache color enabled state in the dpu crtc obj (Dmitry)
>> - simplify dspp allocation while creating crtc (Dmitry)
>> - register for color when crtc is created (Dmitry)
>>
>> Signed-off-by: Kalyan Thota <quic_kalyant@xxxxxxxxxxx>
>> ---
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    |  5 +--
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h    |  6 ++--
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c |  7 ++--
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c     | 53
>++++++++++++++++++++++++++++-
>>   4 files changed, 64 insertions(+), 7 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..ca4c3b3 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
>> @@ -1571,7 +1571,7 @@ static const struct drm_crtc_helper_funcs
>> dpu_crtc_helper_funcs = {
>>
>>   /* initialize crtc */
>>   struct drm_crtc *dpu_crtc_init(struct drm_device *dev, struct drm_plane
>*plane,
>> -                             struct drm_plane *cursor)
>> +                             struct drm_plane *cursor, unsigned long
>> + features)
>>   {
>>       struct drm_crtc *crtc = NULL;
>>       struct dpu_crtc *dpu_crtc = NULL; @@ -1583,6 +1583,7 @@ struct
>> drm_crtc *dpu_crtc_init(struct drm_device *dev, struct drm_plane
>> *plane,
>>
>>       crtc = &dpu_crtc->base;
>>       crtc->dev = dev;
>> +     dpu_crtc->color_enabled = features & BIT(DPU_DSPP_PCC);
>>
>>       spin_lock_init(&dpu_crtc->spin_lock);
>>       atomic_set(&dpu_crtc->frame_pending, 0); @@ -1604,7 +1605,7 @@
>> 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);
>> +     drm_crtc_enable_color_mgmt(crtc, 0, dpu_crtc->color_enabled, 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..342f9ae 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
>> @@ -136,6 +136,7 @@ struct dpu_crtc_frame_event {
>>    * @enabled       : whether the DPU CRTC is currently enabled. updated in the
>>    *                  commit-thread, not state-swap time which is earlier, so
>>    *                  safe to make decisions on during VBLANK on/off work
>> + * @color_enabled : whether crtc supports color management
>>    * @feature_list  : list of color processing features supported on a crtc
>>    * @active_list   : list of color processing features are active
>>    * @dirty_list    : list of color processing features are dirty
>> @@ -164,7 +165,7 @@ struct dpu_crtc {
>>       u64 play_count;
>>       ktime_t vblank_cb_time;
>>       bool enabled;
>> -
>> +     bool color_enabled;
>>       struct list_head feature_list;
>>       struct list_head active_list;
>>       struct list_head dirty_list;
>> @@ -269,10 +270,11 @@ void dpu_crtc_complete_commit(struct drm_crtc
>*crtc);
>>    * @dev: dpu device
>>    * @plane: base plane
>>    * @cursor: cursor plane
>> + * @features: color features
>>    * @Return: new crtc object or error
>>    */
>>   struct drm_crtc *dpu_crtc_init(struct drm_device *dev, struct drm_plane
>*plane,
>> -                            struct drm_plane *cursor);
>> +                            struct drm_plane *cursor, unsigned long
>> + features);
>>
>>   /**
>>    * dpu_crtc_register_custom_event - api for enabling/disabling crtc
>> event diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> index c9058aa..d72edb8 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
>> @@ -579,6 +579,7 @@ 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 dpu_crtc *dpu_crtc,
>>                       struct drm_display_mode *mode)
>>   {
>>       struct msm_display_topology topology = {0}; @@ -607,7 +608,7 @@
>> 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_crtc->color_enabled) {
>>               if (dpu_kms->catalog->dspp &&
>>                       (dpu_kms->catalog->dspp_count >= topology.num_lm))
>>                       topology.num_dspp = topology.num_lm; @@ -642,6
>> +643,7 @@ static int dpu_encoder_virt_atomic_check(
>>       struct drm_display_mode *adj_mode;
>>       struct msm_display_topology topology;
>>       struct dpu_global_state *global_state;
>> +     struct dpu_crtc *dpu_crtc;
>>       int i = 0;
>>       int ret = 0;
>>
>> @@ -652,6 +654,7 @@ static int dpu_encoder_virt_atomic_check(
>>       }
>>
>>       dpu_enc = to_dpu_encoder_virt(drm_enc);
>> +     dpu_crtc = to_dpu_crtc(crtc_state->crtc);
>>       DPU_DEBUG_ENC(dpu_enc, "\n");
>>
>>       priv = drm_enc->dev->dev_private; @@ -677,7 +680,7 @@ 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, dpu_crtc,
>> + adj_mode);
>>
>>       /* 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 0709da2..ce6f5e6 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c
>> @@ -734,7 +734,54 @@ static int _dpu_kms_setup_displays(struct drm_device
>*dev,
>>       return rc;
>>   }
>>
>> +/**
>> + * _dpu_kms_populate_dspp_features - Evaluate how many dspps pairs can be
>facilitated
>> +                                     to enable color features for encoder and assign
>> +                                  color features prefering primary
>
>preferring
>
>> + * @dpu_kms:    Pointer to dpu kms structure
>> + * @features:   Pointer to feature array
>> + *
>> + * Baring single entry, if atleast 2 dspps are available in the
>> + catalogue,
>
>at least
>
>> + * then color can be enabled for that crtc  */ static void
>> +_dpu_kms_populate_dspp_features(struct dpu_kms *dpu_kms,
>> +     unsigned long *features)
>> +{
>> +     struct drm_encoder *encoder;
>> +     u32 external_enc_mask = 0;
>> +     u32 num_dspps = dpu_kms->catalog->dspp_count;
>> +
>> +     if (!num_dspps)
>> +             return;
>> +     else if (num_dspps > 1)
>> +             num_dspps /= 2;
>> +
>> +     /* Ensure all primary encoders get first allocation of color */
>> +     drm_for_each_encoder(encoder, dpu_kms->dev) {
>> +             if(dpu_encoder_is_primary(encoder)) {
>> +                     if (num_dspps) {
>> +                             features[encoder->index] = dpu_kms->catalog->dspp-
>>features;
>> +                             num_dspps--;
>> +                     }
>> +             } else if(dpu_encoder_is_external(encoder)) {
>> +                     external_enc_mask |= drm_encoder_mask(encoder);
>> +             }
>> +     }
>> +
>> +     if(!num_dspps)
>> +             return;
>> +
>> +     /* Allocate color for external encoders after primary */
>
>Please. No "primary" encoders. You already have sense of internal vs external,
>plugable, or which ever way you would like to call them. You don't need to add
>another safety check, do you?
>
>> +     drm_for_each_encoder_mask(encoder, dpu_kms->dev,
>external_enc_mask) {
>> +             if (num_dspps) {
>> +                     features[encoder->index] = dpu_kms->catalog->dspp->features;
>> +                     num_dspps--;
>> +             }
>> +     }
>> +}
>> +
>>   #define MAX_PLANES 20
>> +#define MAX_ENCODERS 10
>>   static int _dpu_kms_drm_obj_init(struct dpu_kms *dpu_kms)
>>   {
>>       struct drm_device *dev;
>> @@ -749,6 +796,8 @@ 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;
>> +     unsigned long features[MAX_ENCODERS] = {0};
>> +
>>       dev = dpu_kms->dev;
>>       priv = dev->dev_private;
>>       catalog = dpu_kms->catalog;
>> @@ -798,12 +847,14 @@ static int _dpu_kms_drm_obj_init(struct dpu_kms
>*dpu_kms)
>>       }
>>
>>       max_crtc_count = min(max_crtc_count, primary_planes_idx);
>> +     _dpu_kms_populate_dspp_features(dpu_kms, features);
>>
>>       /* Create one CRTC per encoder */
>>       i = 0;
>>       drm_for_each_encoder(encoder, dev) {
>>               if (i < max_crtc_count) {
>> -                     crtc = dpu_crtc_init(dev, primary_planes[i], cursor_planes[i]);
>> +                     crtc = dpu_crtc_init(dev, primary_planes[i], cursor_planes[i],
>> +                                     features[encoder->index]);
>
>A simple counter should be enough. You know the number of 'rich' CRTCs, which
>can get DSPP (or a pair of DSPPs). Then you can create a feature-rich CRTC
>provided the current encoder should use one and if the number of created 'rich'
>CRTCs is not greater than the 'possibly rich'
>number.
Since encoder list is iterative, and pluggable/builtin encoders can be registered in any order. we need to traverse the list 
to pick up preferred encoders so as to attach color features. I couldn't get a logic on how to accomplish that using a counter. can you explain a bit more on the idea that you have.

>
>>                       if (IS_ERR(crtc)) {
>>                               ret = PTR_ERR(crtc);
>>                               return ret;
>
>--
>With best wishes
>Dmitry