Re: [PATCH v2 3/3] drm: panel: add TDO tl070wsh30 panel driver

From: Neil Armstrong <narmstrong@baylibre.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: thierry.reding@gmail.com, linux-amlogic@lists.infradead.org,
	linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 3/3] drm: panel: add TDO tl070wsh30 panel driver
Date: Tue, 8 Sep 2020 09:41:01 +0200	[thread overview]
Message-ID: <479e1299-740a-8a9e-1747-53a626f28d8e@baylibre.com> (raw)
In-Reply-To: <20200907195244.GB558348@ravnborg.org>

Hi,

On 07/09/2020 21:52, Sam Ravnborg wrote:
> Hi Neil.
> 
> On Mon, Sep 07, 2020 at 01:10:27PM +0200, Neil Armstrong wrote:
>> This adds support for the TDO TL070WSH30 TFT-LCD panel module.
>> The panel has a 1024×600 resolution and uses 24 bit RGB per pixel.
>> It provides a MIPI DSI interface to the host, a built-in LED backlight
>> and touch controller.
> 
> Despite a nicely written driver I noticed a few things that needs to be
> addressed.

Thanks for the review, indeed the remove/shutdown was wrong, and I aligned
with panel-simple, which seems more logical.

> 
> 	Sam
>>
>> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
>> ---
>>  drivers/gpu/drm/panel/Kconfig                |  11 +
>>  drivers/gpu/drm/panel/Makefile               |   1 +
>>  drivers/gpu/drm/panel/panel-tdo-tl070wsh30.c | 256 +++++++++++++++++++
>>  3 files changed, 268 insertions(+)
>>  create mode 100644 drivers/gpu/drm/panel/panel-tdo-tl070wsh30.c
>>
>> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
>> index 8d97d07c5871..2d488a875b99 100644
>> --- a/drivers/gpu/drm/panel/Kconfig
>> +++ b/drivers/gpu/drm/panel/Kconfig
>> @@ -433,6 +433,17 @@ config DRM_PANEL_SONY_ACX565AKM
>>  	  Say Y here if you want to enable support for the Sony ACX565AKM
>>  	  800x600 3.5" panel (found on the Nokia N900).
>>  
>> +config DRM_PANEL_TDO_TL070WSH30
>> +	tristate "TDO TL070WSH30 DSI panel"
>> +	depends on OF
>> +	depends on DRM_MIPI_DSI
>> +	depends on BACKLIGHT_CLASS_DEVICE
>> +	help
>> +	  Say Y here if you want to enable support for TDO TL070WSH30 TFT-LCD
>> +	  panel module. The panel has a 1024×600 resolution and uses
>> +	  24 bit RGB per pixel. It provides a MIPI DSI interface to
>> +	  the host, a built-in LED backlight and touch controller.
>> +
>>  config DRM_PANEL_TPO_TD028TTEC1
>>  	tristate "Toppoly (TPO) TD028TTEC1 panel driver"
>>  	depends on OF && SPI
>> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
>> index 15a4e7752951..35ee06a1b5c2 100644
>> --- a/drivers/gpu/drm/panel/Makefile
>> +++ b/drivers/gpu/drm/panel/Makefile
>> @@ -45,6 +45,7 @@ obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7703) += panel-sitronix-st7703.o
>>  obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
>>  obj-$(CONFIG_DRM_PANEL_SONY_ACX424AKP) += panel-sony-acx424akp.o
>>  obj-$(CONFIG_DRM_PANEL_SONY_ACX565AKM) += panel-sony-acx565akm.o
>> +obj-$(CONFIG_DRM_PANEL_TDO_TL070WSH30) += panel-tdo-tl070wsh30.o
>>  obj-$(CONFIG_DRM_PANEL_TPO_TD028TTEC1) += panel-tpo-td028ttec1.o
>>  obj-$(CONFIG_DRM_PANEL_TPO_TD043MTEA1) += panel-tpo-td043mtea1.o
>>  obj-$(CONFIG_DRM_PANEL_TPO_TPG110) += panel-tpo-tpg110.o
>> diff --git a/drivers/gpu/drm/panel/panel-tdo-tl070wsh30.c b/drivers/gpu/drm/panel/panel-tdo-tl070wsh30.c
>> new file mode 100644
>> index 000000000000..c7a6c2c42c52
>> --- /dev/null
>> +++ b/drivers/gpu/drm/panel/panel-tdo-tl070wsh30.c
>> @@ -0,0 +1,256 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (C) 2020 BayLibre, SAS
>> + * Author: Neil Armstrong <narmstrong@baylibre.com>
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/regulator/consumer.h>
>> +
>> +#include <video/mipi_display.h>
>> +
>> +#include <drm/drm_crtc.h>
>> +#include <drm/drm_device.h>
>> +#include <drm/drm_mipi_dsi.h>
>> +#include <drm/drm_modes.h>
>> +#include <drm/drm_panel.h>
>> +
>> +struct tdo_tl070wsh30_panel {
>> +	struct drm_panel base;
>> +	struct mipi_dsi_device *link;
>> +
>> +	struct regulator *supply;
>> +	struct gpio_desc *reset_gpio;
>> +
>> +	bool prepared;
>> +};
>> +
>> +static inline
>> +struct tdo_tl070wsh30_panel *to_tdo_tl070wsh30_panel(struct drm_panel *panel)
>> +{
>> +	return container_of(panel, struct tdo_tl070wsh30_panel, base);
>> +}
> 
> bikeshedding - but my preference is to order the functions:
> 
> prepare
> enable
> disable
> unprepare
> 
> As this is the natural order they are used.
> Feel free to ignore!

Ack, prepare before unprepare looks better !

> 
>> +
>> +static int tdo_tl070wsh30_panel_unprepare(struct drm_panel *panel)
>> +{
>> +	struct tdo_tl070wsh30_panel *tdo_tl070wsh30 = to_tdo_tl070wsh30_panel(panel);
>> +	int err;
>> +
>> +	if (!tdo_tl070wsh30->prepared)
>> +		return 0;
>> +
>> +	err = mipi_dsi_dcs_set_display_off(tdo_tl070wsh30->link);
>> +	if (err < 0)
>> +		dev_err(panel->dev, "failed to set display off: %d\n", err);
>> +
>> +	usleep_range(10000, 11000);
>> +
>> +	err = mipi_dsi_dcs_enter_sleep_mode(tdo_tl070wsh30->link);
>> +	if (err < 0) {
>> +		dev_err(panel->dev, "failed to enter sleep mode: %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	usleep_range(10000, 11000);
>> +
>> +	tdo_tl070wsh30->prepared = false;
>> +
>> +	return 0;
>> +}
>> +
>> +static int tdo_tl070wsh30_panel_prepare(struct drm_panel *panel)
>> +{
>> +	struct tdo_tl070wsh30_panel *tdo_tl070wsh30 = to_tdo_tl070wsh30_panel(panel);
>> +	int err;
>> +
>> +	if (tdo_tl070wsh30->prepared)
>> +		return 0;
>> +
>> +	err = mipi_dsi_dcs_exit_sleep_mode(tdo_tl070wsh30->link);
>> +	if (err < 0) {
>> +		dev_err(panel->dev, "failed to exit sleep mode: %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	msleep(200);
>> +
>> +	err = mipi_dsi_dcs_set_display_on(tdo_tl070wsh30->link);
>> +	if (err < 0) {
>> +		dev_err(panel->dev, "failed to set display on: %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	msleep(20);
>> +
>> +	tdo_tl070wsh30->prepared = true;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct drm_display_mode default_mode = {
>> +	.clock = 47250,
>> +	.hdisplay = 1024,
>> +	.hsync_start = 1024 + 46,
>> +	.hsync_end = 1024 + 46 + 80,
>> +	.htotal = 1024 + 46 + 80 + 100,
>> +	.vdisplay = 600,
>> +	.vsync_start = 600 + 5,
>> +	.vsync_end = 600 + 5 + 5,
>> +	.vtotal = 600 + 5 + 5 + 20,
>> +	.flags = DRM_MODE_FLAG_PHSYNC | DRM_MODE_FLAG_PVSYNC,
>> +};
>> +
>> +static int tdo_tl070wsh30_panel_get_modes(struct drm_panel *panel,
>> +				       struct drm_connector *connector)
>> +{
>> +	struct drm_display_mode *mode;
>> +
>> +	mode = drm_mode_duplicate(connector->dev, &default_mode);
>> +	if (!mode) {
>> +		dev_err(panel->dev, "failed to add mode %ux%ux\n", default_mode.hdisplay,
>> +			default_mode.vdisplay);
> Here we often print the refresh rate too.
> If there is no need for the refresh rate than at least drop the extra
> 'x' at the end of the line.

I forgot to remove it after vrefresh removal, but I'll prefer adding back
drm_mode_vrefresh() and the refresh.

> 
>> +		return -ENOMEM;
>> +	}
>> +
>> +	drm_mode_set_name(mode);
>> +
>> +	drm_mode_probed_add(connector, mode);
>> +
>> +	connector->display_info.width_mm = 154;
>> +	connector->display_info.height_mm = 85;
>> +	connector->display_info.bpc = 8;
>> +
>> +	return 1;
>> +}
>> +
>> +static const struct drm_panel_funcs tdo_tl070wsh30_panel_funcs = {
>> +	.unprepare = tdo_tl070wsh30_panel_unprepare,
>> +	.prepare = tdo_tl070wsh30_panel_prepare,
>> +	.get_modes = tdo_tl070wsh30_panel_get_modes,
>> +};
>> +
>> +static const struct of_device_id tdo_tl070wsh30_of_match[] = {
>> +	{ .compatible = "tdo,tl070wsh30", },
>> +	{ }
> I often recommends
> 	{ /* sentinel },
> 
> but thats just to be consistent with what I see in other drivers.

Let it be consistent.

> 
>> +};
>> +MODULE_DEVICE_TABLE(of, tdo_tl070wsh30_of_match);
>> +
>> +static int tdo_tl070wsh30_panel_add(struct tdo_tl070wsh30_panel *tdo_tl070wsh30)
>> +{
>> +	struct device *dev = &tdo_tl070wsh30->link->dev;
>> +	int err;
>> +
>> +	tdo_tl070wsh30->supply = devm_regulator_get(dev, "power");
>> +	if (IS_ERR(tdo_tl070wsh30->supply))
>> +		return PTR_ERR(tdo_tl070wsh30->supply);
>> +
>> +	tdo_tl070wsh30->reset_gpio = devm_gpiod_get(dev, "reset",
>> +						  GPIOD_OUT_LOW);
>> +	if (IS_ERR(tdo_tl070wsh30->reset_gpio)) {
>> +		err = PTR_ERR(tdo_tl070wsh30->reset_gpio);
>> +		dev_dbg(dev, "failed to get reset gpio: %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	drm_panel_init(&tdo_tl070wsh30->base, &tdo_tl070wsh30->link->dev,
>> +		       &tdo_tl070wsh30_panel_funcs, DRM_MODE_CONNECTOR_DSI);
>> +
>> +	err = drm_panel_of_backlight(&tdo_tl070wsh30->base);
>> +	if (err)
>> +		return err;
> 
> 
> 
>> +
>> +	err = regulator_enable(tdo_tl070wsh30->supply);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	usleep_range(10000, 11000);
>> +
>> +	gpiod_set_value_cansleep(tdo_tl070wsh30->reset_gpio, 1);
>> +
>> +	usleep_range(10000, 11000);
>> +
>> +	gpiod_set_value_cansleep(tdo_tl070wsh30->reset_gpio, 0);
>> +
>> +	msleep(200);
>> +
> 
> It is the job of the prepare function to turn on the panel,
> and likewise the unprepare to turn off the panel.
> Please move the code above to the prepare function.

Moved

> 
> 
>> +	drm_panel_add(&tdo_tl070wsh30->base);
>> +
>> +	return 0;
>> +}
>> +
>> +static void tdo_tl070wsh30_panel_del(struct tdo_tl070wsh30_panel *tdo_tl070wsh30)
>> +{
>> +	drm_panel_remove(&tdo_tl070wsh30->base);
>> +}
> This helper does not gain anything - call drm_panel_remove() direct.

Removed

> 
>> +
>> +static int tdo_tl070wsh30_panel_probe(struct mipi_dsi_device *dsi)
>> +{
>> +	struct tdo_tl070wsh30_panel *tdo_tl070wsh30;
>> +	int err;
>> +
>> +	dsi->lanes = 4;
>> +	dsi->format = MIPI_DSI_FMT_RGB888;
>> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO | MIPI_DSI_MODE_VIDEO_BURST | MIPI_DSI_MODE_LPM;
>> +
>> +	tdo_tl070wsh30 = devm_kzalloc(&dsi->dev, sizeof(*tdo_tl070wsh30),
>> +				    GFP_KERNEL);
>> +	if (!tdo_tl070wsh30)
>> +		return -ENOMEM;
>> +
>> +	mipi_dsi_set_drvdata(dsi, tdo_tl070wsh30);
>> +	tdo_tl070wsh30->link = dsi;
>> +
>> +	err = tdo_tl070wsh30_panel_add(tdo_tl070wsh30);
>> +	if (err < 0)
>> +		return err;
>> +
>> +	return mipi_dsi_attach(dsi);
>> +}
>> +
>> +static int tdo_tl070wsh30_panel_remove(struct mipi_dsi_device *dsi)
>> +{
>> +	struct tdo_tl070wsh30_panel *tdo_tl070wsh30 = mipi_dsi_get_drvdata(dsi);
>> +	int err;
>> +
>> +	err = drm_panel_unprepare(&tdo_tl070wsh30->base);
>> +	if (err < 0)
>> +		dev_err(&dsi->dev, "failed to unprepare panel: %d\n", err);
>> +
>> +	err = drm_panel_disable(&tdo_tl070wsh30->base);
>> +	if (err < 0)
>> +		dev_err(&dsi->dev, "failed to disable panel: %d\n", err);
>> +
> In most panel drivers we just ignore the return results here.

Ok

> 
>> +	err = mipi_dsi_detach(dsi);
>> +	if (err < 0)
>> +		dev_err(&dsi->dev, "failed to detach from DSI host: %d\n", err);
>> +
>> +	tdo_tl070wsh30_panel_del(tdo_tl070wsh30);
>> +
>> +	return 0;
>> +}
>> +
>> +static void tdo_tl070wsh30_panel_shutdown(struct mipi_dsi_device *dsi)
>> +{
>> +	struct tdo_tl070wsh30_panel *tdo_tl070wsh30 = mipi_dsi_get_drvdata(dsi);
>> +
>> +	drm_panel_unprepare(&tdo_tl070wsh30->base);
>> +	drm_panel_disable(&tdo_tl070wsh30->base);
> This is the wrong order. disable before unpreapre.
> 
> 
> I am not sure what is right here - but I see some drivers that only have
> the disable() + unprepare() in their shutdown() method and then the
> remocal in their remove() function.
> That makes sense with this split but I have not looked too deep into it.

No prob, I aligned with panel-simple here.

> 
>> +}
>> +
>> +static struct mipi_dsi_driver tdo_tl070wsh30_panel_driver = {
>> +	.driver = {
>> +		.name = "panel-tdo-tl070wsh30",
>> +		.of_match_table = tdo_tl070wsh30_of_match,
>> +	},
>> +	.probe = tdo_tl070wsh30_panel_probe,
>> +	.remove = tdo_tl070wsh30_panel_remove,
>> +	.shutdown = tdo_tl070wsh30_panel_shutdown,
>> +};
>> +module_mipi_dsi_driver(tdo_tl070wsh30_panel_driver);
>> +
>> +MODULE_AUTHOR("Neil Armstrong <narmstrong@baylibre.com>");
>> +MODULE_DESCRIPTION("TDO TL070WSH30 panel driver");
>> +MODULE_LICENSE("GPL v2");
>> -- 
>> 2.22.0
>>
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel

Thanks,
Neil