Re: [Freedreno] [PATCH 3/3] drm/msm/dpu: Add interface support for CRC debugfs

[Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>]

On 28/05/2022 01:23, Jessica Zhang wrote:
> On 5/27/2022 12:46 PM, Dmitry Baryshkov wrote:
> > On 27/05/2022 21:54, Jessica Zhang wrote:
> > > Add support for writing CRC values for the interface block to
> > > the debugfs by calling the necessary MISR setup/collect methods.
> > >
> > > Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
> > > ---
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c    | 43 ++++++++++++++-
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h    |  3 +
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c | 61 +++++++++++++++++++++
> > >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.h | 22 ++++++++
> > >   4 files changed, 128 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c 
> > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > index ae09466663cf..e830fb1e910d 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.c
> > > @@ -79,6 +79,8 @@ static enum dpu_crtc_crc_source 
> > > dpu_crtc_parse_crc_source(const char *src_name)
> > >       if (!strcmp(src_name, "auto") ||
> > >           !strcmp(src_name, "lm"))
> > >           return DPU_CRTC_CRC_SOURCE_LAYER_MIXER;
> > > +    if (!strcmp(src_name, "intf"))
> > > +        return DPU_CRTC_CRC_SOURCE_INTF;
> > >       return DPU_CRTC_CRC_SOURCE_INVALID;
> > >   }
> > > @@ -94,8 +96,18 @@ static int dpu_crtc_verify_crc_source(struct 
> > > drm_crtc *crtc,
> > >           return -EINVAL;
> > >       }
> > > -    if (source == DPU_CRTC_CRC_SOURCE_LAYER_MIXER)
> > > +    if (source == DPU_CRTC_CRC_SOURCE_LAYER_MIXER) {
> > >           *values_cnt = crtc_state->num_mixers;
> > > +    } else if (source == DPU_CRTC_CRC_SOURCE_INTF) {
> > > +        struct drm_encoder *drm_enc = get_encoder_from_crtc(crtc);
> >
> > Let's do this correctly from the beginning. The CRTC can drive several 
> > encoders. Do we want to get CRC from all of them or just from the 
> > first one?
>
> In the case of multiple encoders, it would be better to collect CRCs 
> from all of them.

Then this should become a loop.

> > > +
> > > +        if (!drm_enc) {
> > > +            DRM_ERROR("no encoder found for crtc %d\n", crtc->index);
> > > +            return -ENODATA;
> > > +        }
> > > +
> > > +        *values_cnt = dpu_encoder_get_num_phys(drm_enc);
> > > +    }
> > >       return 0;
> > >   }
> > > @@ -116,6 +128,18 @@ static void dpu_crtc_setup_lm_misr(struct 
> > > dpu_crtc_state *crtc_state)
> > >       }
> > >   }
> > > +static void dpu_crtc_setup_encoder_misr(struct drm_crtc *crtc)
> > > +{
> > > +    struct drm_encoder *drm_enc = get_encoder_from_crtc(crtc);
> > > +
> > > +    if (!drm_enc) {
> > > +        DRM_ERROR("no encoder found for crtc %d\n", crtc->index);
> > > +        return;
> > > +    }
> > > +
> > > +    dpu_encoder_setup_misr(drm_enc);
> > > +}
> > > +
> > >   static int dpu_crtc_set_crc_source(struct drm_crtc *crtc, const 
> > > char *src_name)
> > >   {
> > >       enum dpu_crtc_crc_source source = 
> > > dpu_crtc_parse_crc_source(src_name);
> > > @@ -164,6 +188,8 @@ static int dpu_crtc_set_crc_source(struct 
> > > drm_crtc *crtc, const char *src_name)
> > >       if (source == DPU_CRTC_CRC_SOURCE_LAYER_MIXER)
> > >           dpu_crtc_setup_lm_misr(crtc_state);
> > > +    else if (source == DPU_CRTC_CRC_SOURCE_INTF)
> > > +        dpu_crtc_setup_encoder_misr(crtc);
> > >   cleanup:
> > >       drm_modeset_unlock(&crtc->mutex);
> > > @@ -212,6 +238,18 @@ static int dpu_crtc_get_lm_crc(struct drm_crtc 
> > > *crtc, struct dpu_crtc_state *crt
> > >               drm_crtc_accurate_vblank_count(crtc), crcs);
> > >   }
> > > +static int dpu_crtc_get_encoder_crc(struct drm_crtc *crtc)
> > > +{
> > > +    struct drm_encoder *drm_enc =  get_encoder_from_crtc(crtc);
> > > +
> > > +    if (!drm_enc) {
> > > +        DRM_ERROR("no encoder found for crtc %d\n", crtc->index);
> > > +        return -EINVAL;
> > > +    }
> > > +
> > > +    return dpu_encoder_get_crc(drm_enc);
> > > +}
> > > +
> > >   static int dpu_crtc_get_crc(struct drm_crtc *crtc)
> > >   {
> > >       struct dpu_crtc_state *crtc_state;
> > > @@ -227,6 +265,9 @@ static int dpu_crtc_get_crc(struct drm_crtc *crtc)
> > >       if (crtc_state->crc_source == DPU_CRTC_CRC_SOURCE_LAYER_MIXER)
> > >           return dpu_crtc_get_lm_crc(crtc, crtc_state);
> > > +    if (crtc_state->crc_source == DPU_CRTC_CRC_SOURCE_INTF)
> > > +        return dpu_crtc_get_encoder_crc(crtc);
> > > +
> > >       return 0;
> > >   }
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h 
> > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> > > index b8785c394fcc..a60af034905d 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_crtc.h
> > > @@ -1,5 +1,6 @@
> > >   /* SPDX-License-Identifier: GPL-2.0-only */
> > >   /*
> > > + * Copyright (c) 2022 Qualcomm Innovation Center, Inc. All rights 
> > > reserved.
> > >    * Copyright (c) 2015-2021 The Linux Foundation. All rights reserved.
> > >    * Copyright (C) 2013 Red Hat
> > >    * Author: Rob Clark <robdclark@xxxxxxxxx>
> > > @@ -73,11 +74,13 @@ struct dpu_crtc_smmu_state_data {
> > >    * enum dpu_crtc_crc_source: CRC source
> > >    * @DPU_CRTC_CRC_SOURCE_NONE: no source set
> > >    * @DPU_CRTC_CRC_SOURCE_LAYER_MIXER: CRC in layer mixer
> > > + * @DPU_CRTC_CRC_SOURCE_INTF: CRC in phys interface
> > >    * @DPU_CRTC_CRC_SOURCE_INVALID: Invalid source
> > >    */
> > >   enum dpu_crtc_crc_source {
> > >       DPU_CRTC_CRC_SOURCE_NONE = 0,
> > >       DPU_CRTC_CRC_SOURCE_LAYER_MIXER,
> > > +    DPU_CRTC_CRC_SOURCE_INTF,
> > >       DPU_CRTC_CRC_SOURCE_MAX,
> > >       DPU_CRTC_CRC_SOURCE_INVALID = -1
> > >   };
> > > diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c 
> > > b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > index 52516eb20cb8..7740515f462d 100644
> > > --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder.c
> > > @@ -14,6 +14,7 @@
> > >   #include <drm/drm_crtc.h>
> > >   #include <drm/drm_file.h>
> > > +#include <drm/drm_vblank.h>
> > >   #include <drm/drm_probe_helper.h>
> > >   #include "msm_drv.h"
> > > @@ -225,6 +226,66 @@ bool dpu_encoder_is_widebus_enabled(const struct 
> > > drm_encoder *drm_enc)
> > >       return dpu_enc->wide_bus_en;
> > >   }
> > > +int dpu_encoder_get_num_phys(const struct drm_encoder *drm_enc)
> > > +{
> > > +    struct dpu_encoder_virt *dpu_enc;
> > > +
> > > +    dpu_enc = to_dpu_encoder_virt(drm_enc);
> > > +
> > > +    return dpu_enc->num_phys_encs;
> > > +}
> > > +
> > > +void dpu_encoder_setup_misr(const struct drm_encoder *drm_enc)
> > > +{
> > > +    struct dpu_encoder_virt *dpu_enc;
> > > +
> > > +    int i;
> > > +
> > > +    dpu_enc = to_dpu_encoder_virt(drm_enc);
> > > +
> > > +    for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> > > +        struct dpu_encoder_phys *phys = dpu_enc->phys_encs[i];
> > > +
> > > +        if (!phys->hw_intf || !phys->hw_intf->ops.setup_misr)
> > > +            continue;
> >
> > Does WB support CRC?
>
> AFAIK, no.
>
> > > +
> > > +        phys->hw_intf->ops.setup_misr(phys->hw_intf, true, 1);
> > > +    }
> > > +}
> > > +
> > > +int dpu_encoder_get_crc(const struct drm_encoder *drm_enc)
> > > +{
> > > +    struct dpu_encoder_virt *dpu_enc;
> > > +    u32 crcs[MAX_PHYS_ENCODERS_PER_VIRTUAL];
> > > +
> > > +    int i, rc;
> > > +
> > > +    if (!drm_enc->crtc) {
> > > +        DRM_ERROR("no crtc found for encoder %d\n", drm_enc->index);
> > > +        return -EINVAL;
> > > +    }
> > > +
> > > +    dpu_enc = to_dpu_encoder_virt(drm_enc);
> > > +
> > > +    for (i = 0; i < dpu_enc->num_phys_encs; i++) {
> > > +        struct dpu_encoder_phys *phys = dpu_enc->phys_encs[i];
> > > +
> > > +        if (!phys->hw_intf || !phys->hw_intf->ops.collect_misr)
> > > +            continue;
> > > +
> > > +        rc = phys->hw_intf->ops.collect_misr(phys->hw_intf, &crcs[i]);
> >
> > This doesn't look fully correct. Do we need to skip the indices for 
> > the phys without a backing hw_intf?
>
> Sorry if I'm misunderstanding your question, but don't we need to have a 
> backing hw_intf (and skip if there isn't any) since the methods for 
> collecting/setting MISR registers is within the hw_intf?

Yes. So the question if we should skip the phys and leave the crcs[i] 
untouched, skip the phys and sset crcs[i] to 0 or change 
dpu_crtc_parse_crc_source() to return the number of intf-backed 
phys_enc's and do not skip any crcs[i].


> > > +
> >
> > Extra empty line.
>
> Noted
>
> > > +        if (rc) {
> > > +            if (rc != -ENODATA)
> >
> > Do we need to handle ENODATA in any specific way (like zeroing the 
> > crcs[i])? If not, I'd suggest to drop this return code. Let's make an 
> > error always an error.
>
> This is a carry-over from this change [1]. We wanted to have the ENODATA 
> check to avoid spamming the driver debug logs when CRC is disabled for 
> this block.
>
> [1] 
> https://gitlab.freedesktop.org/drm/msm/-/commit/3ce8bdca394fc606b55e7c5ed779d171aaae5d09 

Thanks for the reminder. I commented this in the previous patch now.



--
With best wishes
Dmitry