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Subject: Re: [PATCH] drm/msm/dp: add voltage corners voting support base on dp
 link rate
To:     Stephen Boyd <swboyd@chromium.org>,
        Kuogee Hsieh <khsieh@codeaurora.org>, robdclark@gmail.com,
        sean@poorly.run
Cc:     tanmay@codeaurora.org, abhinavk@codeaurora.org,
        aravindh@codeaurora.org, airlied@linux.ie, daniel@ffwll.ch,
        linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org,
        freedreno@lists.freedesktop.org, linux-kernel@vger.kernel.org
References: <20200929171026.30551-1-khsieh@codeaurora.org>
 <160145429763.310579.786737478429183087@swboyd.mtv.corp.google.com>
From:   Rajendra Nayak <rnayak@codeaurora.org>
Message-ID: <01467014-1190-6e1b-8120-472719861a5e@codeaurora.org>
Date:   Wed, 30 Sep 2020 21:54:57 +0530
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On 9/30/2020 1:54 PM, Stephen Boyd wrote:
> Quoting Kuogee Hsieh (2020-09-29 10:10:26)
>> Set link rate by using OPP set rate api so that CX level will be set
>> accordingly base on the link rate.
> 
> s/base/based/
> 
>>
>> Signed-off-by: Kuogee Hsieh <khsieh@codeaurora.org>
>> ---
>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> index 2e3e1917351f..e1595d829e04 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
>> @@ -1849,6 +1853,21 @@ struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link,
>>                  return ERR_PTR(-ENOMEM);
>>          }
>>   
>> +       ctrl->opp_table = dev_pm_opp_set_clkname(dev, "ctrl_link");

I see that downstream has multiple DP clocks which end up voting on CX, we don't have a
way of associating multiple OPP tables with a device upstream, so whats usually done is
(assuming all the clocks get scaled in lock step, which I assume is the case here) we pick
the clock with the 'highest' CX requirement and associate that with the OPP table.
I haven't looked but I am hoping thats how we have decided to associate "ctrl_link" clock
here?

>> +
>> +       if (IS_ERR(ctrl->opp_table)) {
>> +               dev_err(dev, "invalid DP OPP table in device tree\n");
>> +               ctrl->opp_table = NULL;
>> +       } else {
>> +               /* OPP table is optional */
>> +               ret = dev_pm_opp_of_add_table(dev);
>> +               if (ret && ret != -ENODEV) {
>> +                       dev_err(dev, "add DP OPP table\n");
> 
> This is debug noise right?
> 
>> +                       dev_pm_opp_put_clkname(ctrl->opp_table);
>> +                       ctrl->opp_table = NULL;
>> +               }
>> +       }
>> +
>>          init_completion(&ctrl->idle_comp);
>>          init_completion(&ctrl->video_comp);
>>   
>> @@ -1864,6 +1883,18 @@ struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link,
>>          return &ctrl->dp_ctrl;
>>   }
>>   
>> -void dp_ctrl_put(struct dp_ctrl *dp_ctrl)
>> +void dp_ctrl_put(struct device *dev, struct dp_ctrl *dp_ctrl)
>>   {
>> +       struct dp_ctrl_private *ctrl;
>> +
>> +       if (!dp_ctrl)
> 
> Can this happen?
> 
>> +               return;
>> +
>> +       ctrl = container_of(dp_ctrl, struct dp_ctrl_private, dp_ctrl);
>> +
>> +       if (ctrl->opp_table != NULL) {
> 
> This is usually written as
> 
> 	if (ctrl->opp_table)
> 
>> +               dev_pm_opp_of_remove_table(dev);
>> +               dev_pm_opp_put_clkname(ctrl->opp_table);
>> +               ctrl->opp_table = NULL;
>> +       }
>>   }
>> diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.h b/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> index f60ba93c8678..19b412a93e02 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> +++ b/drivers/gpu/drm/msm/dp/dp_ctrl.h
>> @@ -31,6 +31,6 @@ struct dp_ctrl *dp_ctrl_get(struct device *dev, struct dp_link *link,
>>                          struct dp_panel *panel, struct drm_dp_aux *aux,
>>                          struct dp_power *power, struct dp_catalog *catalog,
>>                          struct dp_parser *parser);
>> -void dp_ctrl_put(struct dp_ctrl *dp_ctrl);
>> +void dp_ctrl_put(struct device *dev, struct dp_ctrl *dp_ctrl);
> 
> Is 'dev' not inside 'dp_ctrl'?
> 
>>   
>>   #endif /* _DP_CTRL_H_ */
>> diff --git a/drivers/gpu/drm/msm/dp/dp_power.c b/drivers/gpu/drm/msm/dp/dp_power.c
>> index 17c1fc6a2d44..3d75bf09e38f 100644
>> --- a/drivers/gpu/drm/msm/dp/dp_power.c
>> +++ b/drivers/gpu/drm/msm/dp/dp_power.c
>> @@ -8,12 +8,14 @@
>>   #include <linux/clk.h>
>>   #include <linux/clk-provider.h>
>>   #include <linux/regulator/consumer.h>
>> +#include <linux/pm_opp.h>
>>   #include "dp_power.h"
>>   #include "msm_drv.h"
>>   
>>   struct dp_power_private {
>>          struct dp_parser *parser;
>>          struct platform_device *pdev;
>> +       struct device *dev;
>>          struct clk *link_clk_src;
>>          struct clk *pixel_provider;
>>          struct clk *link_provider;
>> @@ -148,18 +150,49 @@ static int dp_power_clk_deinit(struct dp_power_private *power)
>>          return 0;
>>   }
>>   
>> +static int dp_power_clk_set_link_rate(struct dp_power_private *power,
>> +                       struct dss_clk *clk_arry, int num_clk, int enable)
>> +{
>> +       u32 rate;
>> +       int i, rc = 0;
>> +
>> +       for (i = 0; i < num_clk; i++) {
>> +               if (clk_arry[i].clk) {
>> +                       if (clk_arry[i].type == DSS_CLK_PCLK) {
>> +                               if (enable)
>> +                                       rate = clk_arry[i].rate;
>> +                               else
>> +                                       rate = 0;
>> +
>> +                               rc = dev_pm_opp_set_rate(power->dev, rate);
> 
> Why do we keep going if rc is non-zero?
> 
>> +                       }
>> +
>> +               }
>> +       }
>> +       return rc;
>> +}
>> +
>>   static int dp_power_clk_set_rate(struct dp_power_private *power,
>>                  enum dp_pm_type module, bool enable)
>>   {
>>          int rc = 0;
>>          struct dss_module_power *mp = &power->parser->mp[module];
>>   
>> -       if (enable) {
>> -               rc = msm_dss_clk_set_rate(mp->clk_config, mp->num_clk);
>> +       if (module == DP_CTRL_PM) {
>> +               rc = dp_power_clk_set_link_rate(power, mp->clk_config, mp->num_clk, enable);
>>                  if (rc) {
>> -                       DRM_ERROR("failed to set clks rate.\n");
>> +                       DRM_ERROR("failed to set link clks rate.\n");
>>                          return rc;
>>                  }
>> +       } else {
>> +
>> +               if (enable) {
>> +                       rc = msm_dss_clk_set_rate(mp->clk_config, mp->num_clk);
>> +                       if (rc) {
>> +                               DRM_ERROR("failed to set clks rate.\n");
> 
> Not sure we need the period on these error messages.
> 
>> +                               return rc;
>> +                       }
>> +               }
>>          }
>>   
>>          rc = msm_dss_enable_clk(mp->clk_config, mp->num_clk, enable);
>>
>> base-commit: 3c0f462da069af12211901ddf26f7e16e6951d9b
>> prerequisite-patch-id: a109eaf08147f50149ad661a58122b6745a52445
> 
> Can you rebase this on Rob's msm-next tree
> (https://gitlab.freedesktop.org/drm/msm.git) and test? It doesn't apply
> for me because I have the dp phy patch from there.
> 

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