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Message-ID: <283a4ae4-c0ea-13f9-fb47-e44f366c26b2@quicinc.com>
Date:   Thu, 29 Jun 2023 20:07:40 -0700
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Subject: Re: [PATCH v3 2/3] drm/msm/dpu: use dpu core's major version to
 enable data compress
Content-Language: en-US
To:     Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
        <freedreno@lists.freedesktop.org>, Rob Clark <robdclark@gmail.com>,
        Sean Paul <sean@poorly.run>,
        Marijn Suijten <marijn.suijten@somainline.org>,
        "David Airlie" <airlied@gmail.com>, Daniel Vetter <daniel@ffwll.ch>
CC:     <dri-devel@lists.freedesktop.org>, <quic_jesszhan@quicinc.com>,
        <andersson@kernel.org>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>
References: <20230629193001.22618-1-quic_abhinavk@quicinc.com>
 <20230629193001.22618-2-quic_abhinavk@quicinc.com>
 <17b3b652-194c-99c2-e460-21663040c398@linaro.org>
From:   Abhinav Kumar <quic_abhinavk@quicinc.com>
In-Reply-To: <17b3b652-194c-99c2-e460-21663040c398@linaro.org>
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On 6/29/2023 5:20 PM, Dmitry Baryshkov wrote:
> On 29/06/2023 22:29, Abhinav Kumar wrote:
>> Instead of using a feature bit to decide whether to enable data
>> compress or not for DSC use-cases, use dpu core's major version instead.
>> This will avoid defining feature bits for every bit level details of
>> registers.
>>
>> Also, rename the intf's enable_compression() op to program_datapath()
>> and allow it to accept a struct intf_dpu_datapath_cfg to program
>> all the bits at once. This can be re-used by widebus later on as
>> well as it touches the same register.
> 
> Two separate commits please, because...
> 

I thought of it but it seemed better together and was the only way I 
could think of. Please see below.

>> Signed-off-by: Abhinav Kumar <quic_abhinavk@quicinc.com>
>> ---
>>   .../gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c |  9 +++++++--
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c      |  9 +++++----
>>   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h      | 16 ++++++++++++++--
>>   3 files changed, 26 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> index b856c6286c85..f4e15b4c4cc9 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c
>> @@ -50,6 +50,7 @@ static void _dpu_encoder_phys_cmd_update_intf_cfg(
>>               to_dpu_encoder_phys_cmd(phys_enc);
>>       struct dpu_hw_ctl *ctl;
>>       struct dpu_hw_intf_cfg intf_cfg = { 0 };
>> +    struct dpu_kms *dpu_kms = phys_enc->dpu_kms;
>>       ctl = phys_enc->hw_ctl;
>>       if (!ctl->ops.setup_intf_cfg)
>> @@ -68,8 +69,12 @@ static void _dpu_encoder_phys_cmd_update_intf_cfg(
>>                   phys_enc->hw_intf,
>>                   phys_enc->hw_pp->idx);
>> -    if (intf_cfg.dsc != 0 && phys_enc->hw_intf->ops.enable_compression)
>> -        phys_enc->hw_intf->ops.enable_compression(phys_enc->hw_intf);
>> +    if (intf_cfg.dsc != 0 && dpu_kms->catalog->core_major_version >= 
>> 0x7) {
> 
> ... because this becomes incorrect. The datapath should be programmed in 
> all the cases, if there is a corresponding callback. intf_cfg.dsc should 
> be used as a condition to set datapath_cfg.
> 

The issue is that today we do not have dpu_mdss_cfg as part of 
dpu_hw_intf nor _setup_intf_ops because all of those have been dropped 
with some rework or cleanup.

Ideally even I would like to assign this op only for core_rev >=7 but 
that information is no longer available. We would have to start passing 
the major and minor versions to _setup_intf_ops() to go with that 
approach. So without making all of those changes, the only way I had was 
to assign the op unconditionally but call it only for major_rev >= 7.

Passing core_rev to the op itself so that we can write the register only 
for core_rev >=7 is an option but then what if some bits start becoming 
usable only after minor rev. then we will have to start passing major 
and minor rev to program_datapath too. Again getting little messy.

I am open to ideas to achieve the goal of assigning this op only for 
core_rev >=7 other than what I wrote above.

> 
>> +        struct intf_dpu_datapath_cfg datapath_cfg = { 0 };
> 
> No need for `0' in the init, empty braces would be enough.
> 

ack.

>> +
>> +        datapath_cfg.data_compress = true;
>> +        phys_enc->hw_intf->ops.program_datapath(phys_enc->hw_intf, 
>> &datapath_cfg);
>> +    }
>>   }
>>   static void dpu_encoder_phys_cmd_pp_tx_done_irq(void *arg, int irq_idx)
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> index 5b0f6627e29b..85333df08fbc 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c
>> @@ -513,11 +513,13 @@ static void 
>> dpu_hw_intf_disable_autorefresh(struct dpu_hw_intf *intf,
>>   }
>> -static void dpu_hw_intf_enable_compression(struct dpu_hw_intf *ctx)
>> +static void dpu_hw_intf_program_datapath(struct dpu_hw_intf *ctx,
>> +                     struct intf_dpu_datapath_cfg *datapath_cfg)
>>   {
>>       u32 intf_cfg2 = DPU_REG_READ(&ctx->hw, INTF_CONFIG2);
>> -    intf_cfg2 |= INTF_CFG2_DCE_DATA_COMPRESS;
>> +    if (datapath_cfg->data_compress)
>> +        intf_cfg2 |= INTF_CFG2_DCE_DATA_COMPRESS;
>>       DPU_REG_WRITE(&ctx->hw, INTF_CONFIG2, intf_cfg2);
>>   }
>> @@ -543,8 +545,7 @@ static void _setup_intf_ops(struct dpu_hw_intf_ops 
>> *ops,
>>           ops->disable_autorefresh = dpu_hw_intf_disable_autorefresh;
>>       }
>> -    if (cap & BIT(DPU_INTF_DATA_COMPRESS))
>> -        ops->enable_compression = dpu_hw_intf_enable_compression;
>> +    ops->program_datapath = dpu_hw_intf_program_datapath;
> 
> The `core_major_version >= 7' should either be here or in the callback 
> itself.
> 

Yes, ideally I would like it like that but please see above why I 
couldnt do it.

>>   }
>>   struct dpu_hw_intf *dpu_hw_intf_init(const struct dpu_intf_cfg *cfg,
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h 
>> b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> index 99e21c4137f9..f736dca38463 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h
>> @@ -48,6 +48,11 @@ struct intf_status {
>>       u32 line_count;        /* current line count including blanking */
>>   };
>> +struct intf_dpu_datapath_cfg {
>> +    u8 data_compress;    /* enable data compress between dpu and dsi */
>> +    /* can be expanded for other programmable bits */
>> +};
> 
> I'd say, dpu_datapath is too generic. What about  intf_cmd_mode_cfg?
> 

The goal was to keep it generic. Its actually the handshake between DPU 
and interface datapath so I chose that name.

This is not specific to command mode and intf_cfg is already there so I 
chose that one :)

>> +
>>   /**
>>    * struct dpu_hw_intf_ops : Interface to the interface Hw driver 
>> functions
>>    *  Assumption is these functions will be called after clocks are 
>> enabled
>> @@ -70,7 +75,7 @@ struct intf_status {
>>    * @get_autorefresh:            Retrieve autorefresh config from 
>> hardware
>>    *                              Return: 0 on success, -ETIMEDOUT on 
>> timeout
>>    * @vsync_sel:                  Select vsync signal for tear-effect 
>> configuration
>> - * @enable_compression:         Enable data compression
>> + * @program_datapath:           Program the DPU to interface datapath 
>> for relevant chipsets
>>    */
>>   struct dpu_hw_intf_ops {
>>       void (*setup_timing_gen)(struct dpu_hw_intf *intf,
>> @@ -108,7 +113,14 @@ struct dpu_hw_intf_ops {
>>        */
>>       void (*disable_autorefresh)(struct dpu_hw_intf *intf, uint32_t 
>> encoder_id, u16 vdisplay);
>> -    void (*enable_compression)(struct dpu_hw_intf *intf);
>> +    /**
>> +     * Program the DPU to intf datapath by specifying
>> +     * which of the settings need to be programmed for
>> +     * use-cases which need DPU-intf handshake such as
>> +     * widebus, compression etc.
> 
> This is not a valid kerneldoc.
> 

hmmm ... ok so just // ?

I referred disable_autorefresh from above and did the same.

>> +     */
>> +    void (*program_datapath)(struct dpu_hw_intf *intf,
>> +                 struct intf_dpu_datapath_cfg *datapath_cfg);
>>   };
>>   struct dpu_hw_intf {
>