RE: [PATCH v4 4/5] drm: renesas: rz-du: Move mode_valid logic to per-SoC clock limits

[Biju Das]

Hi Prabhakar,

> -----Original Message-----
> From: Lad, Prabhakar <prabhakar.csengg@xxxxxxxxx>
> Sent: 20 May 2026 09:14
> Subject: Re: [PATCH v4 4/5] drm: renesas: rz-du: Move mode_valid logic to per-SoC clock limits
> 
> Hi Biju,
> 
> Thank you for the review.
> 
> On Wed, May 20, 2026 at 6:36 AM Biju Das <biju.das.jz@xxxxxxxxxxxxxx> wrote:
> >
> > Hi Prabhakar,
> >
> > Thanks for the patch.
> >
> > > -----Original Message-----
> > > From: Prabhakar <prabhakar.csengg@xxxxxxxxx>
> > > Sent: 19 May 2026 17:08
> > > Subject: [PATCH v4 4/5] drm: renesas: rz-du: Move mode_valid logic
> > > to per-SoC clock limits
> > >
> > > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > >
> > > Move pixel clock validation from a fixed encoder check to per SoC
> > > constraints stored in rzg2l_du_device_info.
> > >
> > > Pixel clock limits differ across SoCs in the RZ DU family and cannot
> > > be expressed by a single shared rule. For example, RZ/G2UL and
> > > RZ/G2L limit the DPAD0 pixel clock to a narrow window, while other SoCs such as RZ/T2H require a
> wider operating range.
> > >
> > > Add mode_clock_min and mode_clock_max fields to rzg2l_du_device_info
> > > to describe the supported pixel clock range for each SoC. Update
> > > rzg2l_du_encoder_mode_valid() to check these bounds when evaluating
> > > DPAD0 outputs, returning MODE_CLOCK_LOW when the pixel clock falls
> > > below mode_clock_min and MODE_CLOCK_HIGH when it exceeds mode_clock_max.
> > >
> > > Populate the pixel clock limits for both the RZ/G2UL (R9A07G043U)
> > > and RZ/G2L (R9A07G044) variants to a minimum of 20875 kHz and a
> > > maximum of
> > > 83500 kHz.
> > >
> > > Signed-off-by: Lad Prabhakar
> > > <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > > ---
> > > v3->v4:
> > > - Dropped per pad limits
> > > - Updated commit message to reflect the change in approach.
> > >
> > > v2->v3:
> > > - Moved clock limits from device_info to output_routing to allow
> > >   per-output constraints.
> > > - Updated commit message to reflect the change in approach.
> > >
> > > v1->v2:
> > > - Dropped storing info pointer in struct rzg2l_du_encoder as it's not needed.
> > > ---
> > >  drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.c     | 6 +++++-
> > >  drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h     | 4 ++++
> > >  drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c | 9 ++++++++-
> > >  3 files changed, 17 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.c
> > > b/drivers/gpu/drm/renesas/rz- du/rzg2l_du_drv.c index
> > > 0fef33a5a089..1e4b9f38c55b 100644
> > > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.c
> > > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.c
> > > @@ -35,6 +35,8 @@ static const struct rzg2l_du_device_info rzg2l_du_r9a07g043u_info = {
> > >                       .port = 0,
> > >               },
> > >       },
> > > +     .mode_clock_min = 20875,
> > > +     .mode_clock_max = 83500,
> > >  };
> > >
> > >  static const struct rzg2l_du_device_info rzg2l_du_r9a07g044_info =
> > > { @@ -48,7 +50,9 @@ static const struct rzg2l_du_device_info rzg2l_du_r9a07g044_info = {
> > >                       .possible_outputs = BIT(0),
> > >                       .port = 1,
> > >               }
> > > -     }
> > > +     },
> > > +     .mode_clock_min = 20875,
> > > +     .mode_clock_max = 83500,
> > >  };
> > >
> > >  static const struct rzg2l_du_device_info rzg2l_du_r9a09g057_info =
> > > { diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h
> > > b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h
> > > index 58806c2a8f2b..885558eb9547 100644
> > > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h
> > > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_drv.h
> > > @@ -44,10 +44,14 @@ struct rzg2l_du_output_routing {
> > >   * struct rzg2l_du_device_info - DU model-specific information
> > >   * @channels_mask: bit mask of available DU channels
> > >   * @routes: array of CRTC to output routes, indexed by output
> > > (RZG2L_DU_OUTPUT_*)
> > > + * @mode_clock_min: minimum pixel clock in kHz
> > > + * @mode_clock_max: maximum pixel clock in kHz
> > >   */
> > >  struct rzg2l_du_device_info {
> > >       unsigned int channels_mask;
> > >       struct rzg2l_du_output_routing routes[RZG2L_DU_OUTPUT_MAX];
> > > +     u32 mode_clock_min;
> > > +     u32 mode_clock_max;
> > >  };
> > >
> > >  #define RZG2L_DU_MAX_CRTCS           1
> > > diff --git a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> > > b/drivers/gpu/drm/renesas/rz- du/rzg2l_du_encoder.c index
> > > 0e567b57a408..56220139a149 100644
> > > --- a/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> > > +++ b/drivers/gpu/drm/renesas/rz-du/rzg2l_du_encoder.c
> > > @@ -50,8 +50,15 @@ rzg2l_du_encoder_mode_valid(struct drm_encoder *encoder,
> > >                           const struct drm_display_mode *mode)  {
> > >       struct rzg2l_du_encoder *renc = to_rzg2l_encoder(encoder);
> > > +     struct rzg2l_du_device *rcdu = to_rzg2l_du_device(renc->base.dev);
> > > +     const struct rzg2l_du_device_info *info = rcdu->info;
> > >
> > > -     if (renc->output == RZG2L_DU_OUTPUT_DPAD0 && mode->clock > 83500)
> > > +     if (renc->output != RZG2L_DU_OUTPUT_DPAD0)
> > > +             return MODE_OK;
> > > +
> > > +     if (info->mode_clock_min && mode->clock <
> > > + info->mode_clock_min)
> >
> > I will avoid checking the first part as it is mandatory for SoCs with
> > DPI support and DPI check above make sure that this part of the code
> > is reachable only for DPI output.
> >
> Will you fix up while applying or shall I send a new version?

I can take care of this if there are no other comments.

Cheers,
Biju

> 
> Cheers,
> Prabhakar
> > > +             return MODE_CLOCK_LOW;
> > > +     if (info->mode_clock_max && mode->clock >
> > > + info->mode_clock_max)
> >
> > Same here.
> >
> > Cheers,
> > Biju
> >
> > >               return MODE_CLOCK_HIGH;
> > >
> > >       return MODE_OK;
> > > --
> > > 2.54.0
> >