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

[Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>]

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@ideasonboard.com>
>> ---
>>   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