Re: [PATCH 2/3] drm/msm/dpu: Set DATABUS_WIDEN on command mode encoders

[Abhinav Kumar]

On 6/14/2023 12:56 AM, Dmitry Baryshkov wrote:
> On 14/06/2023 04:57, Jessica Zhang wrote:
> > Add a DPU INTF op to set the DATABUS_WIDEN register to enable the
> > databus-widen mode datapath.
> >
> > Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_encoder_phys_cmd.c |  3 +++
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.c          | 12 ++++++++++++
> >   drivers/gpu/drm/msm/disp/dpu1/dpu_hw_intf.h          |  3 +++
> >   3 files changed, 18 insertions(+)
> >
> > 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..124ba96bebda 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
> > @@ -70,6 +70,9 @@ static void _dpu_encoder_phys_cmd_update_intf_cfg(
> >       if (intf_cfg.dsc != 0 && phys_enc->hw_intf->ops.enable_compression)
> >           phys_enc->hw_intf->ops.enable_compression(phys_enc->hw_intf);
> > +
> > +    if (phys_enc->hw_intf->ops.enable_widebus)
> > +        phys_enc->hw_intf->ops.enable_widebus(phys_enc->hw_intf);
>
> No. Please provide a single function which takes necessary 
> configuration, including compression and wide_bus_enable.

There are two ways to look at this. Your point is coming from the 
perspective that its programming the same register but just a different 
bit. But that will also make it a bit confusing.

So lets say the function is called intf_cfg2_xxx(..., bool widebus, bool 
data_compress)

Now for the caller who wants to just enable widebus this will be

intf_cfg2_xxx(....., true, false)

if we want to do both

intf_cfg2_xxx(...., true, true)

the last one where we want to do just data_compress(highly unlikely and 
not recommended)

intf_cfg2_xxx(...., false, true)

Now someone looking at the code will have to go and find out what each 
bool is.

Whereas with separate ops, its kind of implicit.

For that reason, I dont think this patch is bad at all.