linux-kernel - Re: [PATCH v4 2/4] drm/bridge: add Microchip DSI controller support for sam9x7 SoC series

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Message-ID: <pjc75xbvdn4n7tqzjx33st2lf6bzryrs7zixahbv7j4fi5xa7j@xujs6wx7qeqs>
Date: Fri, 20 Sep 2024 19:15:29 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Manikandan Muralidharan <manikandan.m@...rochip.com>
Cc: andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, airlied@...il.com, 
	simona@...ll.ch, maarten.lankhorst@...ux.intel.com, mripard@...nel.org, 
	tzimmermann@...e.de, robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, 
	linux@...linux.org.uk, nicolas.ferre@...rochip.com, alexandre.belloni@...tlin.com, 
	claudiu.beznea@...on.dev, dharma.b@...rochip.com, arnd@...db.de, 
	hari.prasathge@...rochip.com, dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 2/4] drm/bridge: add Microchip DSI controller support
 for sam9x7 SoC series

On Wed, Sep 18, 2024 at 04:01:17PM GMT, Manikandan Muralidharan wrote:
> Add the Microchip's DSI controller wrapper driver that uses
> the Synopsys DesignWare MIPI DSI host controller bridge.
> 
> Signed-off-by: Manikandan Muralidharan <manikandan.m@...rochip.com>
> ---
> changes in v4:
> - Fixed issues reported by kernel test robot
> - replaced syscon_regmap_lookup_by_phandle with
> syscon_regmap_lookup_by_compatible
> 
> changes in v3:
> - make remove callback return void
> 
> changes in v2:
> - use static const with global variables
> - replace dev_err with dev_err_probe
> - move clk_prepare_enable to simplify the error path
> - use FIELD_PREP calls
> - remove unused macros and unused functions
> - rename function name with mchp_ suffix
> - add suspend and resume pm calls to handle pllref_clk
> ---
>  drivers/gpu/drm/bridge/Kconfig            |   8 +
>  drivers/gpu/drm/bridge/Makefile           |   1 +
>  drivers/gpu/drm/bridge/dw-mipi-dsi-mchp.c | 545 ++++++++++++++++++++++
>  3 files changed, 554 insertions(+)
>  create mode 100644 drivers/gpu/drm/bridge/dw-mipi-dsi-mchp.c
> 
> diff --git a/drivers/gpu/drm/bridge/Kconfig b/drivers/gpu/drm/bridge/Kconfig
> index 683cb33805b2..317246509601 100644
> --- a/drivers/gpu/drm/bridge/Kconfig
> +++ b/drivers/gpu/drm/bridge/Kconfig
> @@ -196,6 +196,14 @@ config DRM_MICROCHIP_LVDS_SERIALIZER
>  	help
>  	  Support for Microchip's LVDS serializer.
>  
> +config DRM_MICROCHIP_DW_MIPI_DSI
> +	tristate "Microchip specific extensions for Synopsys DW MIPI DSI"
> +	depends on DRM_ATMEL_HLCDC
> +	select DRM_DW_MIPI_DSI
> +	help
> +	  This selects support for Microchip's SoC specific extensions
> +	  for the Synopsys DesignWare dsi driver.
> +
>  config DRM_NWL_MIPI_DSI
>  	tristate "Northwest Logic MIPI DSI Host controller"
>  	depends on DRM
> diff --git a/drivers/gpu/drm/bridge/Makefile b/drivers/gpu/drm/bridge/Makefile
> index 3daf803ce80b..32e4233e6b5e 100644
> --- a/drivers/gpu/drm/bridge/Makefile
> +++ b/drivers/gpu/drm/bridge/Makefile
> @@ -14,6 +14,7 @@ obj-$(CONFIG_DRM_LONTIUM_LT9611UXC) += lontium-lt9611uxc.o
>  obj-$(CONFIG_DRM_LVDS_CODEC) += lvds-codec.o
>  obj-$(CONFIG_DRM_MEGACHIPS_STDPXXXX_GE_B850V3_FW) += megachips-stdpxxxx-ge-b850v3-fw.o
>  obj-$(CONFIG_DRM_MICROCHIP_LVDS_SERIALIZER) += microchip-lvds.o
> +obj-$(CONFIG_DRM_MICROCHIP_DW_MIPI_DSI) += dw-mipi-dsi-mchp.o
>  obj-$(CONFIG_DRM_NXP_PTN3460) += nxp-ptn3460.o
>  obj-$(CONFIG_DRM_PARADE_PS8622) += parade-ps8622.o
>  obj-$(CONFIG_DRM_PARADE_PS8640) += parade-ps8640.o
> diff --git a/drivers/gpu/drm/bridge/dw-mipi-dsi-mchp.c b/drivers/gpu/drm/bridge/dw-mipi-dsi-mchp.c
> new file mode 100644
> index 000000000000..35cfca1ff000
> --- /dev/null
> +++ b/drivers/gpu/drm/bridge/dw-mipi-dsi-mchp.c
> @@ -0,0 +1,545 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2024 Microchip Technology Inc. and its subsidiaries
> + *
> + * Author: Manikandan Muralidharan <manikandan.m@...rochip.com>
> + *
> + */
> +

[...]

> +
> +static int dw_mipi_dsi_mchp_get_lane_mbps(void *priv_data,
> +					  const struct drm_display_mode *mode,
> +					  unsigned long mode_flags, u32 lanes,
> +					  u32 format, unsigned int *lane_mbps)
> +{
> +	struct dw_mipi_dsi_mchp *dsi = priv_data;
> +	unsigned long best_freq, fvco_min, fvco_max, fin, fout;
> +	unsigned long min_delta = ULONG_MAX, delta;
> +	unsigned int target_mbps = 0, mpclk, desired_mbps;
> +	unsigned int max_mbps = dppa_map[ARRAY_SIZE(dppa_map) - 1].max_mbps;
> +	unsigned int min_prediv, max_prediv;
> +	unsigned int _fbdiv, best_fbdiv, _prediv, best_prediv;
> +	int bpp;
> +	u64 freq_factor;

This function is significantly overlapping with dw_mipi_dsi_get_lane_mbps().
Please extract a common helper and add it to dw-mipi-dsi.c. Other than
that, LGTM.

> +
> +	dsi->format = format;
> +	bpp = mipi_dsi_pixel_format_to_bpp(dsi->format);
> +	if (bpp < 0) {
> +		dev_err(dsi->dev,
> +			"failed to get bpp for pixel format %d\n",
> +			dsi->format);
> +		return bpp;
> +	}
> +
-- 
With best wishes
Dmitry