From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=FPao=NG=vger.kernel.org=linux-kernel-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-7.5 required=3.0 tests=DKIM_ADSP_ALL,DKIM_INVALID,
	DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,
	SIGNED_OFF_BY,SPF_PASS,USER_AGENT_NEOMUTT autolearn=unavailable
	autolearn_force=no version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 1D7B5ECDE46
	for <linux-kernel@archiver.kernel.org>; Fri, 26 Oct 2018 16:22:20 +0000 (UTC)
Received: from vger.kernel.org (vger.kernel.org [209.132.180.67])
	by mail.kernel.org (Postfix) with ESMTP id A9E7F20665
	for <linux-kernel@archiver.kernel.org>; Fri, 26 Oct 2018 16:22:19 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=fail reason="signature verification failed" (2048-bit key) header.d=plaes.org header.i=@plaes.org header.b="bcGaZCJZ"
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A9E7F20665
Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=plaes.org
Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1727667AbeJ0A76 (ORCPT
        <rfc822;linux-kernel@archiver.kernel.org>);
        Fri, 26 Oct 2018 20:59:58 -0400
Received: from plaes.org ([188.166.43.21]:57838 "EHLO plaes.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1727240AbeJ0A75 (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 26 Oct 2018 20:59:57 -0400
X-Greylist: delayed 532 seconds by postgrey-1.27 at vger.kernel.org; Fri, 26 Oct 2018 20:59:55 EDT
Received: from plaes.org (localhost [127.0.0.1])
        by plaes.org (Postfix) with ESMTPSA id 260244011A;
        Fri, 26 Oct 2018 16:13:25 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=plaes.org; s=mail;
        t=1540570405; bh=1mo3kqSxTjC6rPYQaoc78xe5NzatoQn/XoH2Q/kKxnE=;
        h=Date:From:To:Cc:Subject:References:In-Reply-To:From;
        b=bcGaZCJZbwrhXMVuO0Iq7thgeGJ03FB34y3ZWPTdahS0T+QrYGmd83RqvFvYYtWa9
         gmG3CKuLSW3C+u/Il7JaARCwASTp3S4+eKXkYQ1zgffVxaQHJl7bpbx/n2LjgM585e
         9zU/1bsiKY8ZuzMjx2r0wByScXO6VbXtfj54+RAQkvH+ykrGhm9ml1wYWwJ+dpWZlG
         dD1nK2zJlJe1ZeXowm/YBGxwqWlizCTXQgwqr7wcHX0FB4OS0KvgkfyhzQfX+7aDSW
         zXrMsgnMdn7tB9Fh8lpd+2Fl5ZvsuJbUR3jyVSnBRUte8q03X6as8s3jrfPFDcfZxG
         YxmGoBJIuYUdw==
Date:   Fri, 26 Oct 2018 16:13:24 +0000
From:   Priit Laes <plaes@plaes.org>
To:     Jagan Teki <jagan@amarulasolutions.com>
Cc:     Maxime Ripard <maxime.ripard@bootlin.com>,
        Chen-Yu Tsai <wens@csie.org>, Icenowy Zheng <icenowy@aosc.io>,
        Jernej Skrabec <jernej.skrabec@siol.net>,
        Vasily Khoruzhick <anarsoul@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>,
        David Airlie <airlied@linux.ie>,
        dri-devel@lists.freedesktop.org,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>, linux-clk@vger.kernel.org,
        Michael Trimarchi <michael@amarulasolutions.com>,
        linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com
Subject: Re: [linux-sunxi] [PATCH v3 20/25] drm/panel: Add Techstar TS8550B
 MIPI-DSI LCD panel
Message-ID: <20181026161324.qbpcpkpwyixi7juk@plaes.org>
References: <20181026144344.27778-1-jagan@amarulasolutions.com>
 <20181026144344.27778-21-jagan@amarulasolutions.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20181026144344.27778-21-jagan@amarulasolutions.com>
User-Agent: NeoMutt/20170113 (1.7.2)
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Fri, Oct 26, 2018 at 08:13:39PM +0530, Jagan Teki wrote:
> Techstar TS8550B MIPI DSI panel is 480x854, 2-lane MIPI DSI
> LCD panel. Add panel driver for it.
> 
> Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
> Tested-by: Jagan Teki <jagan@amarulasolutions.com>
> ---
> Changes for v3:
> - new patch
> Changes for v2:
> - none
> 
>  drivers/gpu/drm/panel/Kconfig                 |   9 +
>  drivers/gpu/drm/panel/Makefile                |   1 +
>  .../gpu/drm/panel/panel-techstar-ts8550b.c    | 346 ++++++++++++++++++
>  3 files changed, 356 insertions(+)
>  create mode 100644 drivers/gpu/drm/panel/panel-techstar-ts8550b.c
> 
> diff --git a/drivers/gpu/drm/panel/Kconfig b/drivers/gpu/drm/panel/Kconfig
> index 20b88c275421..d0d4e60f5153 100644
> --- a/drivers/gpu/drm/panel/Kconfig
> +++ b/drivers/gpu/drm/panel/Kconfig
> @@ -195,4 +195,13 @@ config DRM_PANEL_SITRONIX_ST7789V
>  	  Say Y here if you want to enable support for the Sitronix
>  	  ST7789V controller for 240x320 LCD panels
>  
> +config DRM_PANEL_TECHSTAR_TS8550B
> +	tristate "Techstar TS8550B MIPI-DSI panel driver"
> +	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
> +	  Techstar TS8550B MIPI-DSI interface.
> +
>  endmenu
> diff --git a/drivers/gpu/drm/panel/Makefile b/drivers/gpu/drm/panel/Makefile
> index 04696bb85218..88011f06edb8 100644
> --- a/drivers/gpu/drm/panel/Makefile
> +++ b/drivers/gpu/drm/panel/Makefile
> @@ -20,3 +20,4 @@ obj-$(CONFIG_DRM_PANEL_SEIKO_43WVF1G) += panel-seiko-43wvf1g.o
>  obj-$(CONFIG_DRM_PANEL_SHARP_LQ101R1SX01) += panel-sharp-lq101r1sx01.o
>  obj-$(CONFIG_DRM_PANEL_SHARP_LS043T1LE01) += panel-sharp-ls043t1le01.o
>  obj-$(CONFIG_DRM_PANEL_SITRONIX_ST7789V) += panel-sitronix-st7789v.o
> +obj-$(CONFIG_DRM_PANEL_TECHSTAR_TS8550B) += panel-techstar-ts8550b.o
> diff --git a/drivers/gpu/drm/panel/panel-techstar-ts8550b.c b/drivers/gpu/drm/panel/panel-techstar-ts8550b.c
> new file mode 100644
> index 000000000000..8baca71595a7
> --- /dev/null
> +++ b/drivers/gpu/drm/panel/panel-techstar-ts8550b.c
> @@ -0,0 +1,346 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2019, Amarula Solutions.
> + * Author: Jagan Teki <jagan@amarulasolutions.com>
> + */
> +
> +#include <linux/backlight.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/errno.h>
> +#include <linux/fb.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +
> +#include <linux/gpio/consumer.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include <drm/drm_mipi_dsi.h>
> +#include <drm/drm_modes.h>
> +#include <drm/drm_panel.h>
> +
> +#include <video/mipi_display.h>
> +
> +struct ts8550b {
> +	struct drm_panel	panel;
> +	struct mipi_dsi_device	*dsi;
> +
> +	struct backlight_device *backlight;
> +	struct regulator	*dvdd;
> +	struct regulator	*avdd;
> +	struct gpio_desc	*reset;
> +
> +	bool			is_enabled;
> +	bool			is_prepared;
> +};
> +
> +static inline struct ts8550b *panel_to_ts8550b(struct drm_panel *panel)
> +{
> +	return container_of(panel, struct ts8550b, panel);
> +}
> +
> +static inline int ts8550b_dcs_write_seq(struct ts8550b *ctx, const void *seq,
> +					size_t len)
> +{
> +	return mipi_dsi_dcs_write_buffer(ctx->dsi, seq, len);
> +};
> +
> +#define ts8550b_dcs_write_seq_static(ctx, seq...)		\
> +	({							\
> +		static const u8 d[] = { seq };			\
> +		ts8550b_dcs_write_seq(ctx, d, ARRAY_SIZE(d));	\
> +	})
> +
> +static void ts8550b_init_sequence(struct ts8550b *ctx)

This seems to be pretty "standard" MIPI-based display, utilizing
bunch of manufacturer-specific commands during init sequence.

Standard MIPI commands fall between 0x00..0xAF and are defined in <video/mipi.h>

> +{
> +	ts8550b_dcs_write_seq_static(ctx, 0x01, 0x00);


MIPI_DCS_SOFT_RESET

> +	msleep(200);
> +	ts8550b_dcs_write_seq_static(ctx, 0xFF, 0x77, 0x01, 0x00, 0x00, 0x11);
> +	ts8550b_dcs_write_seq_static(ctx, 0xD1, 0x11);
> +	ts8550b_dcs_write_seq_static(ctx, 0x11, 0x00);

MIPI_DCS_EXIT_SLEEP_MODE

> +	msleep(200);
> +	ts8550b_dcs_write_seq_static(ctx, 0xFF, 0x77, 0x01, 0x00, 0x00, 0x10);
> +	ts8550b_dcs_write_seq_static(ctx, 0xC0, 0xE9, 0x03);
> +	ts8550b_dcs_write_seq_static(ctx, 0xC1, 0x12, 0x02);
> +	ts8550b_dcs_write_seq_static(ctx, 0xC2, 0x07, 0x06);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB0, 0x00, 0x0E, 0x15, 0x0F, 0x11,
> +				     0x08, 0x08, 0x08, 0x08, 0x23, 0x04, 0x13,
> +				     0x12, 0x2B, 0x34, 0x1F);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB1, 0x00, 0x0E, 0x95, 0x0F, 0x13,
> +				     0x07, 0x09, 0x08, 0x08, 0x22, 0x04, 0x10,
> +				     0x0E, 0x2C, 0x34, 0x1F);
> +	ts8550b_dcs_write_seq_static(ctx, 0xFF, 0x77, 0x01, 0x00, 0x00, 0x11);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB0, 0x45);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB1, 0x13);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB2, 0x07);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB3, 0x80);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB5, 0x47);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB7, 0x85);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB8, 0x20);
> +	ts8550b_dcs_write_seq_static(ctx, 0xB9, 0x11);
> +	ts8550b_dcs_write_seq_static(ctx, 0xC1, 0x78);
> +	ts8550b_dcs_write_seq_static(ctx, 0xC2, 0x78);
> +	ts8550b_dcs_write_seq_static(ctx, 0xD0, 0x88);
> +	msleep(100);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE0, 0x00, 0x00, 0x02);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE1, 0x0B, 0x00, 0x0D, 0x00, 0x0C,
> +				     0x00, 0x0E, 0x00, 0x00, 0x44, 0x44);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE2, 0x33, 0x33, 0x44, 0x44, 0x64,
> +				     0x00, 0x66, 0x00, 0x65, 0x00, 0x67, 0x00,
> +				     0x00);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE3, 0x00, 0x00, 0x33, 0x33);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE4, 0x44, 0x44);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE5, 0x0C, 0x78, 0x3C, 0xA0, 0x0E,
> +				     0x78, 0x3C, 0xA0, 0x10, 0x78, 0x3C, 0xA0,
> +				     0x12, 0x78, 0x3C, 0xA0);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE6, 0x00, 0x00, 0x33, 0x33);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE7, 0x44, 0x44);
> +	ts8550b_dcs_write_seq_static(ctx, 0xE8, 0x0D, 0x78, 0x3C, 0xA0, 0x0F,
> +				     0x78, 0x3C, 0xA0, 0x11, 0x78, 0x3C, 0xA0,
> +				     0x13, 0x78, 0x3C, 0xA0);
> +	ts8550b_dcs_write_seq_static(ctx, 0xEB, 0x02, 0x02, 0x39, 0x39, 0xEE,
> +				     0x44, 0x00);
> +	ts8550b_dcs_write_seq_static(ctx, 0xEC, 0x00, 0x00);
> +	ts8550b_dcs_write_seq_static(ctx, 0xED, 0xFF, 0xF1, 0x04, 0x56, 0x72,
> +				     0x3F, 0xFF, 0xFF, 0xFF, 0xFF, 0xF3, 0x27,
> +				     0x65, 0x40, 0x1F, 0xFF);
> +	ts8550b_dcs_write_seq_static(ctx, 0xFF, 0x77, 0x01, 0x00, 0x00, 0x00);
> +	msleep(10);
> +	ts8550b_dcs_write_seq_static(ctx, 0x29, 0x00);

MIPI_DCS_SET_DISPLAY_ON

> +	msleep(200);
> +}
> +
> +static int ts8550b_prepare(struct drm_panel *panel)
> +{
> +	struct ts8550b *ctx = panel_to_ts8550b(panel);
> +	int ret;
> +
> +	if (ctx->is_prepared)
> +		return 0;
> +
> +	gpiod_set_value(ctx->reset, 0);
> +	msleep(20);
> +
> +	ret = regulator_enable(ctx->dvdd);
> +	if (ret)
> +		return ret;
> +	msleep(20);
> +
> +	ret = regulator_enable(ctx->avdd);
> +	if (ret)
> +		return ret;
> +	msleep(20);
> +
> +	gpiod_set_value(ctx->reset, 1);
> +	msleep(20);
> +
> +	gpiod_set_value(ctx->reset, 0);
> +	msleep(30);
> +
> +	gpiod_set_value(ctx->reset, 1);
> +	msleep(150);
> +
> +	ts8550b_init_sequence(ctx);
> +
> +	ctx->is_prepared = true;
> +
> +	return 0;
> +}
> +
> +static int ts8550b_enable(struct drm_panel *panel)
> +{
> +	struct ts8550b *ctx = panel_to_ts8550b(panel);
> +
> +	if (ctx->is_enabled)
> +		return 0;
> +
> +	msleep(120);
> +
> +	backlight_enable(ctx->backlight);
> +	ctx->is_enabled = true;
> +
> +	return 0;
> +}
> +
> +static int ts8550b_disable(struct drm_panel *panel)
> +{
> +	struct ts8550b *ctx = panel_to_ts8550b(panel);
> +
> +	if (!ctx->is_enabled)
> +		return 0;
> +
> +	backlight_disable(ctx->backlight);
> +	ctx->is_enabled = false;
> +
> +	return 0;
> +}
> +
> +static int ts8550b_unprepare(struct drm_panel *panel)
> +{
> +	struct ts8550b *ctx = panel_to_ts8550b(panel);
> +	int ret;
> +
> +	if (!ctx->is_prepared)
> +		return 0;
> +
> +	ret = mipi_dsi_dcs_set_display_off(ctx->dsi);
> +	if (ret < 0)
> +		dev_err(panel->dev, "failed to set display off: %d\n", ret);
> +
> +	ret = mipi_dsi_dcs_enter_sleep_mode(ctx->dsi);
> +	if (ret < 0)
> +		dev_err(panel->dev, "failed to enter sleep mode: %d\n", ret);
> +
> +	msleep(120);
> +
> +	regulator_disable(ctx->dvdd);
> +
> +	regulator_disable(ctx->avdd);
> +
> +	gpiod_set_value(ctx->reset, 0);
> +
> +	gpiod_set_value(ctx->reset, 1);
> +
> +	gpiod_set_value(ctx->reset, 0);
> +
> +	ctx->is_prepared = false;
> +
> +	return 0;
> +}
> +
> +static const struct drm_display_mode default_mode = {
> +	.clock		= 27500,
> +	.vrefresh	= 60,
> +
> +	.hdisplay	= 480,
> +	.hsync_start	= 480 + 38,
> +	.hsync_end	= 480 + 38 + 12,
> +	.htotal		= 480 + 38 + 12 + 12,
> +
> +	.vdisplay	= 854,
> +	.vsync_start	= 854 + 18,
> +	.vsync_end	= 854 + 18 + 8,
> +	.vtotal		= 854 + 18 + 8 + 4,
> +};
> +
> +static int ts8550b_get_modes(struct drm_panel *panel)
> +{
> +	struct drm_connector *connector = panel->connector;
> +	struct ts8550b *ctx = panel_to_ts8550b(panel);
> +	struct drm_display_mode *mode;
> +
> +	mode = drm_mode_duplicate(panel->drm, &default_mode);
> +	if (!mode) {
> +		dev_err(&ctx->dsi->dev, "failed to add mode %ux%ux@%u\n",
> +			default_mode.hdisplay, default_mode.vdisplay,
> +			default_mode.vrefresh);
> +		return -ENOMEM;
> +	}
> +
> +	drm_mode_set_name(mode);
> +
> +	mode->type = DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED;
> +	drm_mode_probed_add(connector, mode);
> +
> +	panel->connector->display_info.width_mm = 69;
> +	panel->connector->display_info.height_mm = 139;
> +
> +	return 1;
> +}
> +
> +static const struct drm_panel_funcs ts8550b_funcs = {
> +	.disable	= ts8550b_disable,
> +	.unprepare	= ts8550b_unprepare,
> +	.prepare	= ts8550b_prepare,
> +	.enable		= ts8550b_enable,
> +	.get_modes	= ts8550b_get_modes,
> +};
> +
> +static int ts8550b_dsi_probe(struct mipi_dsi_device *dsi)
> +{
> +	struct device_node *np;
> +	struct ts8550b *ctx;
> +	int ret;
> +
> +	ctx = devm_kzalloc(&dsi->dev, sizeof(*ctx), GFP_KERNEL);
> +	if (!ctx)
> +		return -ENOMEM;
> +
> +	mipi_dsi_set_drvdata(dsi, ctx);
> +	ctx->dsi = dsi;
> +
> +	drm_panel_init(&ctx->panel);
> +	ctx->panel.dev = &dsi->dev;
> +	ctx->panel.funcs = &ts8550b_funcs;
> +
> +	ctx->dvdd = devm_regulator_get(&dsi->dev, "dvdd");
> +	if (IS_ERR(ctx->dvdd)) {
> +		dev_err(&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)) {
> +		dev_err(&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)) {
> +		dev_err(&dsi->dev, "Couldn't get our reset GPIO\n");
> +		return PTR_ERR(ctx->reset);
> +	}
> +
> +	np = of_parse_phandle(dsi->dev.of_node, "backlight", 0);
> +	if (np) {
> +		ctx->backlight = of_find_backlight_by_node(np);
> +		of_node_put(np);
> +
> +		if (!ctx->backlight)
> +			return -EPROBE_DEFER;
> +	}
> +
> +	ret = drm_panel_add(&ctx->panel);
> +	if (ret < 0)
> +		return ret;
> +
> +	dsi->mode_flags = MIPI_DSI_MODE_VIDEO;
> +	dsi->format = MIPI_DSI_FMT_RGB888;
> +	dsi->lanes = 2;
> +
> +	return mipi_dsi_attach(dsi);
> +}
> +
> +static int ts8550b_dsi_remove(struct mipi_dsi_device *dsi)
> +{
> +	struct ts8550b *ctx = mipi_dsi_get_drvdata(dsi);
> +
> +	mipi_dsi_detach(dsi);
> +	drm_panel_remove(&ctx->panel);
> +
> +	if (ctx->backlight)
> +		put_device(&ctx->backlight->dev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id ts8550b_of_match[] = {
> +	{ .compatible = "techstar,ts8550b" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, ts8550b_of_match);
> +
> +static struct mipi_dsi_driver ts8550b_dsi_driver = {
> +	.probe		= ts8550b_dsi_probe,
> +	.remove		= ts8550b_dsi_remove,
> +	.driver = {
> +		.name		= "techstar-ts8550b",
> +		.of_match_table	= ts8550b_of_match,
> +	},
> +};
> +module_mipi_dsi_driver(ts8550b_dsi_driver);
> +
> +MODULE_AUTHOR("Jagan Teki <jagan@amarulasolutions.com>");
> +MODULE_DESCRIPTION("Techstar TS8550B MIPI-DSI LCD Panel Driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.18.0.321.gffc6fa0e3
> 
> -- 
> You received this message because you are subscribed to the Google Groups "linux-sunxi" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to linux-sunxi+unsubscribe@googlegroups.com.
> For more options, visit https://groups.google.com/d/optout.