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Date:   Thu, 24 Jan 2019 20:50:35 +0100
From:   Sam Ravnborg <sam@ravnborg.org>
To:     Jagan Teki <jagan@amarulasolutions.com>
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Michael Trimarchi <michael@amarulasolutions.com>,
        linux-amarula@amarulasolutions.com, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v4 2/2] drm/panel: Add Feiyang FY07024DI26A30-D MIPI-DSI
 LCD panel
Message-ID: <20190124195035.GB4783@ravnborg.org>
References: <20190124184313.30193-1-jagan@amarulasolutions.com>
 <20190124184313.30193-2-jagan@amarulasolutions.com>
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Hi Jagan.

Thanks for this nice patch, a few comments below.

On Fri, Jan 25, 2019 at 12:13:13AM +0530, Jagan Teki wrote:
> Feiyang FY07024DI26A30-D is 1024x600, 4-lane MIPI-DSI LCD panel.
> 
> Add panel driver for it.
> 
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> Changes for v5:
> - rebase on master
> - adjust the hporch values to satisfy the refresh
> Changes for v4:
> - use simple structure for command init
> - update proper comments on power, reset delay sequnce
> - fix to use set_display_off in disable function
> - move mode type to structure
> - drop refres rate value, let drm compute
> Changes for v2:
> - new patch, derived from another dsi series
> 
>  MAINTAINERS                                   |   6 +
>  drivers/gpu/drm/panel/Kconfig                 |   9 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  .../drm/panel/panel-feiyang-fy07024di26a30d.c | 286 ++++++++++++++++++
>  4 files changed, 302 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index e3f785bad68b..5c8591eb5840 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4831,6 +4831,12 @@ T:	git git://anongit.freedesktop.org/drm/drm-misc
>  S:	Maintained
>  F:	drivers/gpu/drm/tve200/
>  
> +DRM DRIVER FOR FEIYANG FY07024DI26A30-D MIPI-DSI LCD PANELS
> +M:	Jagan Teki <jagan@amarulasolutions.com>
> +S:	Maintained
> +F:	drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
> +F:	Documentation/devicetree/bindings/display/panel/feiyang,fy07024di26a30d.txt
> +
>  DRM DRIVER FOR ILITEK ILI9225 PANELS
>  M:	David Lechner <david@lechnology.com>
>  S:	Maintained
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 151ddf720b83..5304db7b7b55 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -47,6 +47,15 @@ config DRM_PANEL_SIMPLE
>  	  that it can be automatically turned off when the panel goes into a
>  	  low power state.
>  
> +config DRM_PANEL_FEIYANG_FY07024DI26A30D
> +	tristate "Feiyang FY07024DI26A30-D MIPI-DSI LCD panel"
> +	depends on OF
> +	depends on DRM_MIPI_DSI
> +	depends on BACKLIGHT_CLASS_DEVICE
> +	help
> +	  Say Y if you want to enable support for panels based on the
> +	  Feiyang FY07024DI26A30-D MIPI-DSI interface.
> +
>  config DRM_PANEL_ILITEK_IL9322
>  	tristate "Ilitek ILI9322 320x240 QVGA panels"
>  	depends on OF && SPI
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 54db0921f329..c88dacf9d439 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -3,6 +3,7 @@ obj-$(CONFIG_DRM_PANEL_ARM_VERSATILE) += panel-arm-versatile.o
>  obj-$(CONFIG_DRM_PANEL_BANANAPI_S070WV20_ICN6211) += panel-bananapi-s070wv20-icn6211.o
>  obj-$(CONFIG_DRM_PANEL_LVDS) += panel-lvds.o
>  obj-$(CONFIG_DRM_PANEL_SIMPLE) += panel-simple.o
> +obj-$(CONFIG_DRM_PANEL_FEIYANG_FY07024DI26A30D) += panel-feiyang-fy07024di26a30d.o
>  obj-$(CONFIG_DRM_PANEL_ILITEK_IL9322) += panel-ilitek-ili9322.o
>  obj-$(CONFIG_DRM_PANEL_ILITEK_ILI9881C) += panel-ilitek-ili9881c.o
>  obj-$(CONFIG_DRM_PANEL_INNOLUX_P079ZCA) += panel-innolux-p079zca.o
> diff --git a/drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c b/drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
> new file mode 100644
> index 000000000000..f655647aeade
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-feiyang-fy07024di26a30d.c
> @@ -0,0 +1,286 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2018 Amarula Solutions
> + * Author: Jagan Teki <jagan@amarulasolutions.com>
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drmP.h>
Please do not use drmP.h in new drivers.
We are slowly gettting rid of it and in drm-misc.git the
drmP.h file no longer contains anything (other than includes/forwards).


> +	gpiod_set_value(ctx->reset, 1);
> +	msleep(50);
> +
> +	gpiod_set_value(ctx->reset, 0);
> +	/* T5 + T6 (avdd rise + video & logic signal rise)
> +	 * T5 >= 10ms, 0 < T6 <= 10ms
> +	 */
> +	msleep(20);
> +
> +	gpiod_set_value(ctx->reset, 1);
Is it really necessary to do a 1 => 0 => 1 cycle here for reset?
panel-simple do not need it.

> +
> +static int feiyang_dsi_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct feiyang *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(&dsi->dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +	mipi_dsi_set_drvdata(dsi, ctx);
Add empty line atfer return -ENOMEM;?

> +	ctx->dsi = dsi;
> +
> +	drm_panel_init(&ctx->panel);
> +	ctx->panel.dev = &dsi->dev;
> +	ctx->panel.funcs = &feiyang_funcs;
> +
> +	ctx->dvdd = devm_regulator_get(&dsi->dev, "dvdd");
> +	if (IS_ERR(ctx->dvdd)) {
> +		DRM_DEV_ERROR(&dsi->dev, "Couldn't get dvdd regulator\n");
> +		return PTR_ERR(ctx->dvdd);
> +	}
> +
> +	ctx->avdd = devm_regulator_get(&dsi->dev, "avdd");
> +	if (IS_ERR(ctx->avdd)) {
> +		DRM_DEV_ERROR(&dsi->dev, "Couldn't get avdd regulator\n");
> +		return PTR_ERR(ctx->avdd);
> +	}
> +
> +	ctx->reset = devm_gpiod_get(&dsi->dev, "reset", GPIOD_OUT_LOW);
> +	if (IS_ERR(ctx->reset)) {
> +		DRM_DEV_ERROR(&dsi->dev, "Couldn't get our reset GPIO\n");
> +		return PTR_ERR(ctx->reset);
> +	}
> +
> +	ctx->backlight = devm_of_find_backlight(&dsi->dev);
> +	if (IS_ERR(ctx->backlight))
> +		return PTR_ERR(ctx->backlight);
> +
> +	ret = drm_panel_add(&ctx->panel);
> +	if (ret < 0)
> +		goto put_backlight;
> +
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO_BURST;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->lanes = 4;
> +
> +	ret = mipi_dsi_attach(dsi);
> +	if (ret < 0)
> +		goto panel_remove;
> +
> +	return ret;
> +
> +panel_remove:
> +	drm_panel_remove(&ctx->panel);
> +put_backlight:
> +	if (ctx->backlight)
> +		put_device(&ctx->backlight->dev);
As devm_of_find_backlight() is used the put_device() will be done for you.
No need to do it here.
I think the same is true for the panel.

> +
> +	return ret;
> +}
> +
> +static int feiyang_dsi_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct feiyang *ctx = mipi_dsi_get_drvdata(dsi);
> +
> +	mipi_dsi_detach(dsi);
> +	drm_panel_remove(&ctx->panel);
> +
> +	if (ctx->backlight)
> +		put_device(&ctx->backlight->dev);

Likewise, use of devm_of_find_backlight() will do this for you.

	Sam