Re: [PATCH v5 4/7] drm/rcar-du: dsi: Support DSC in the pipeline

[Tomi Valkeinen]

Hi,

On 03/07/2026 00:24, Laurent Pinchart wrote:
> Hi Tomi,
>
> Thank you for the patch.
>
> On Mon, Jun 15, 2026 at 04:11:57PM +0300, Tomi Valkeinen wrote:
> > Enabling DSI clocks on rcar-du needs some tricks as the DU dot clock is
> > provided by the DSI. Thus, we call rcar_mipi_dsi_pclk_enable() from the
> > crtc, when enabling the crtc.
> >
> > With DSC (added in upcoming patch) in the pipeline, between the DU and
> > the DSI, the above call path is broken as the crtc tries to call
> > rcar_mipi_dsi_pclk_enable() on the DSC.
> >
> > To solve this problem, make sure we store the DSI bridge to the
> > rcdu->dsi[] array, instead of the first bridge in the DSI pipeline
> > (which can be DCS), by checking the bridge's bridge->type.
> >
> > Signed-off-by: Tomi Valkeinen <tomi.valkeinen+renesas@xxxxxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c | 18 ++++++++++++++++--
> >   drivers/gpu/drm/renesas/rcar-du/rcar_mipi_dsi.c   |  1 +
> >   2 files changed, 17 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> > index db2088529b48..ac85838ab3b8 100644
> > --- a/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> > +++ b/drivers/gpu/drm/renesas/rcar-du/rcar_du_encoder.c
> > @@ -89,9 +89,23 @@ int rcar_du_encoder_init(struct rcar_du_device *rcdu,
> >   				drm_bridge_get(bridge);
> >   
> >   		if (output == RCAR_DU_OUTPUT_DSI0 ||
> > -		    output == RCAR_DU_OUTPUT_DSI1)
> > +		    output == RCAR_DU_OUTPUT_DSI1) {
> > +			struct drm_bridge *dsi_bridge;
> > +
> > +			/*
> > +			 * When we have a DSC block between the DU and the DSI,
> > +			 * the "bridge" points to the DSC. Detect the DSC by looking
> > +			 * at the bridge type, and skip the DSC if the bridge is not
> > +			 * the DSI bridge.
> > +			 */
> > +
> > +			dsi_bridge = bridge->type == DRM_MODE_CONNECTOR_DSI ?
> > +						     bridge :
> > +						     bridge->next_bridge;
>
> The indentation looks weird.
>
> 			dsi_bridge = bridge->type == DRM_MODE_CONNECTOR_DSI
> 				   ? bridge : bridge->next_bridge;
That looks even weirder, you are associating = and ? there. What about:

dsi_bridge = bridge->type == DRM_MODE_CONNECTOR_DSI ?
	     bridge : bridge->next_bridge;

 Tomi