Re: [RFC PATCH] drm/msm: lookup the ICC paths in both mdp5/dpu and mdss devices

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 24/08/2022 00:31, Stephen Boyd wrote:
> Quoting Dmitry Baryshkov (2022-08-05 04:56:30)
>> diff --git a/drivers/gpu/drm/msm/msm_io_utils.c b/drivers/gpu/drm/msm/msm_io_utils.c
>> index 7b504617833a..d02cd29ce829 100644
>> --- a/drivers/gpu/drm/msm/msm_io_utils.c
>> +++ b/drivers/gpu/drm/msm/msm_io_utils.c
>> @@ -124,3 +126,23 @@ void msm_hrtimer_work_init(struct msm_hrtimer_work *work,
>>          work->worker = worker;
>>          kthread_init_work(&work->work, fn);
>>   }
>> +
>> +struct icc_path *msm_icc_get(struct device *dev, const char *name)
>> +{
>> +       struct device *mdss_dev = dev->parent;
>> +       struct icc_path *path;
>> +
>> +       path = of_icc_get(dev, name);
>> +       if (path)
>> +               return path;
>> +
>> +       /*
>> +        * If there are no interconnects attached to the corresponding device
>> +        * node, of_icc_get() will return NULL.
>> +        *
>> +        * If the MDP5/DPU device node doesn't have interconnects, lookup the
>> +        * path in the parent (MDSS) device.
>> +        */
>> +       return of_icc_get(mdss_dev, name);
> 
> Perhaps this would be better served by having another icc_get() API that
> looks in the device and also the parent? Or maybe there should be
> interconnect-ranges (similar to clock-ranges) so that interconnects can
> be mapped to child nodes in DT.

I was not sure how common this situation is, so I did not add the 
helper/API. Typically the driver knows exactly, which node has the 
interconnects. In our case this is complicated because we are 
effectively merging two different driver generations and two different 
bindings. Thus I suppose this situation is quite unique.


-- 
With best wishes
Dmitry