linux-kernel - Re: [PATCH 05/12] drm: sprd: register a DSI bridge and move init code to pre

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Message-ID: <h555ivhoyfykmw44xch6y3bwlqtewgqks33j4rqw4zkcbdkxih@y4pori4lff6h>
Date: Mon, 28 Jul 2025 18:43:47 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Otto Pflüger <otto.pflueger@...cue.de>
Cc: David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>, Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Kevin Tang <kevin.tang@...soc.com>, dri-devel@...ts.freedesktop.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/12] drm: sprd: register a DSI bridge and move init
 code to pre_enable

On Sat, Jul 19, 2025 at 02:09:41PM +0200, Otto Pflüger wrote:
> If a panel needs to send DSI commands during initialization, it sets the
> prepare_prev_first flag, which allows the DSI host to initialize itself
> before the panel's prepare function is called. To support this, the DSI
> host must register a bridge and perform the necessary initialization
> steps in its pre_enable function.
> 
> Implement this for the Unisoc DSI driver by moving the initialization
> code from the encoder callbacks to a bridge and simplify the remaining
> encoder-related code which no longer needs any callbacks.
> 
> Signed-off-by: Otto Pflüger <otto.pflueger@...cue.de>
> ---
>  drivers/gpu/drm/sprd/Kconfig    |   2 +
>  drivers/gpu/drm/sprd/sprd_dsi.c | 143 +++++++++++++++++++++++++---------------
>  drivers/gpu/drm/sprd/sprd_dsi.h |   4 ++
>  3 files changed, 97 insertions(+), 52 deletions(-)
> 
> diff --git a/drivers/gpu/drm/sprd/Kconfig b/drivers/gpu/drm/sprd/Kconfig
> index e22b780fe82248296a7153d02269faf8cd63294f..1afcdbf6f0ee3304f2297835241c9bb10d422154 100644
> --- a/drivers/gpu/drm/sprd/Kconfig
> +++ b/drivers/gpu/drm/sprd/Kconfig
> @@ -2,6 +2,8 @@ config DRM_SPRD
>  	tristate "DRM Support for Unisoc SoCs Platform"
>  	depends on ARCH_SPRD || COMPILE_TEST
>  	depends on DRM && OF
> +	select DRM_BRIDGE_CONNECTOR
> +	select DRM_DISPLAY_HELPER
>  	select DRM_GEM_DMA_HELPER
>  	select DRM_KMS_HELPER
>  	select DRM_MIPI_DSI
> diff --git a/drivers/gpu/drm/sprd/sprd_dsi.c b/drivers/gpu/drm/sprd/sprd_dsi.c
> index 23b0e1dc547a5023ee6ad7d5e1c49e2cec986bf0..43fff12d73f12619da57606a3c4785924e2c1507 100644
> --- a/drivers/gpu/drm/sprd/sprd_dsi.c
> +++ b/drivers/gpu/drm/sprd/sprd_dsi.c
> @@ -11,8 +11,10 @@
>  
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_bridge.h>
> +#include <drm/drm_bridge_connector.h>
>  #include <drm/drm_of.h>
>  #include <drm/drm_probe_helper.h>
> +#include <drm/drm_simple_kms_helper.h>
>  
>  #include "sprd_drm.h"
>  #include "sprd_dpu.h"
> @@ -778,19 +780,53 @@ static void sprd_dphy_fini(struct dsi_context *ctx)
>  	dsi_reg_up(ctx, PHY_INTERFACE_CTRL, RF_PHY_RESET_N, RF_PHY_RESET_N);
>  }
>  
> -static void sprd_dsi_encoder_mode_set(struct drm_encoder *encoder,
> -				      struct drm_display_mode *mode,
> -				 struct drm_display_mode *adj_mode)
> +static int sprd_dsi_encoder_init(struct sprd_dsi *dsi,
> +				 struct device *dev)
> +{
> +	struct drm_encoder *encoder = &dsi->encoder;
> +	u32 crtc_mask;
> +	int ret;
> +
> +	crtc_mask = drm_of_find_possible_crtcs(dsi->drm, dev->of_node);
> +	if (!crtc_mask) {
> +		drm_err(dsi->drm, "failed to find crtc mask\n");
> +		return -EINVAL;
> +	}
> +
> +	drm_dbg(dsi->drm, "find possible crtcs: 0x%08x\n", crtc_mask);
> +
> +	encoder->possible_crtcs = crtc_mask;
> +	ret = drm_simple_encoder_init(dsi->drm, encoder, DRM_MODE_ENCODER_DSI);

The drm_simple_* components are being deprecated. Please open-code
corresponding functionality.

> +	if (ret) {
> +		drm_err(dsi->drm, "failed to init dsi encoder\n");
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +

-- 
With best wishes
Dmitry