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GET /api/patches/1526138/?format=api
{ "id": 1526138, "url": "http://patchwork.ozlabs.org/api/patches/1526138/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pwm/patch/20210909094849.313936-3-u.kleine-koenig@pengutronix.de/", "project": { "id": 38, "url": "http://patchwork.ozlabs.org/api/projects/38/?format=api", "name": "Linux PWM development", "link_name": "linux-pwm", "list_id": "linux-pwm.vger.kernel.org", "list_email": "linux-pwm@vger.kernel.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20210909094849.313936-3-u.kleine-koenig@pengutronix.de>", "list_archive_url": null, "date": "2021-09-09T09:48:49", "name": "[2/2] pwm: Make it explicit that pwm_apply_state() might sleep", "commit_ref": null, "pull_url": null, "state": "accepted", "archived": false, "hash": "b793f2d0a636cd7df3f49dcb74dfcf5eed04b30e", "submitter": { "id": 1476, "url": "http://patchwork.ozlabs.org/api/people/1476/?format=api", "name": "Uwe Kleine-König", "email": "u.kleine-koenig@pengutronix.de" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/linux-pwm/patch/20210909094849.313936-3-u.kleine-koenig@pengutronix.de/mbox/", "series": [ { "id": 261585, "url": "http://patchwork.ozlabs.org/api/series/261585/?format=api", "web_url": "http://patchwork.ozlabs.org/project/linux-pwm/list/?series=261585", "date": "2021-09-09T09:48:47", "name": "pwm: add might_sleep annotations", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/261585/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/1526138/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/1526138/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<linux-pwm-owner@vger.kernel.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@bilbo.ozlabs.org", "Authentication-Results": "ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org\n (client-ip=23.128.96.18; helo=vger.kernel.org;\n envelope-from=linux-pwm-owner@vger.kernel.org; receiver=<UNKNOWN>)", "Received": [ "from vger.kernel.org (vger.kernel.org [23.128.96.18])\n\tby ozlabs.org (Postfix) with ESMTP id 4H4vND5fz3z9sXk\n\tfor <incoming@patchwork.ozlabs.org>; Thu, 9 Sep 2021 19:49:00 +1000 (AEST)", "(majordomo@vger.kernel.org) by vger.kernel.org via listexpand\n id S233215AbhIIJuI (ORCPT <rfc822;incoming@patchwork.ozlabs.org>);\n Thu, 9 Sep 2021 05:50:08 -0400", "from lindbergh.monkeyblade.net ([23.128.96.19]:38486 \"EHLO\n lindbergh.monkeyblade.net\" rhost-flags-OK-OK-OK-OK) by vger.kernel.org\n with ESMTP id S233238AbhIIJuG (ORCPT\n <rfc822;linux-pwm@vger.kernel.org>); Thu, 9 Sep 2021 05:50:06 -0400", "from metis.ext.pengutronix.de (metis.ext.pengutronix.de\n [IPv6:2001:67c:670:201:290:27ff:fe1d:cc33])\n by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D7EEDC06175F\n for <linux-pwm@vger.kernel.org>; Thu, 9 Sep 2021 02:48:57 -0700 (PDT)", "from drehscheibe.grey.stw.pengutronix.de ([2a0a:edc0:0:c01:1d::a2])\n by metis.ext.pengutronix.de with esmtps\n (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256)\n (Exim 4.92)\n (envelope-from <ukl@pengutronix.de>)\n id 1mOGfv-0000GS-RE; Thu, 09 Sep 2021 11:48:55 +0200", "from [2a0a:edc0:0:900:1d::77] (helo=ptz.office.stw.pengutronix.de)\n by drehscheibe.grey.stw.pengutronix.de with esmtp (Exim 4.92)\n (envelope-from <ukl@pengutronix.de>)\n id 1mOGfv-0007fV-AO; Thu, 09 Sep 2021 11:48:55 +0200", "from ukl by ptz.office.stw.pengutronix.de with local (Exim 4.92)\n (envelope-from <ukl@pengutronix.de>)\n id 1mOGfv-0005nE-9K; Thu, 09 Sep 2021 11:48:55 +0200" ], "From": "=?utf-8?q?Uwe_Kleine-K=C3=B6nig?= <u.kleine-koenig@pengutronix.de>", "To": "Thierry Reding <thierry.reding@gmail.com>,\n Lee Jones <lee.jones@linaro.org>", "Cc": "linux-pwm@vger.kernel.org, kernel@pengutronix.de, =?utf-8?q?M=C3=A5rten_?=\n\t=?utf-8?q?Lindahl?= <marten.lindahl@axis.com>", "Subject": "[PATCH 2/2] pwm: Make it explicit that pwm_apply_state() might sleep", "Date": "Thu, 9 Sep 2021 11:48:49 +0200", "Message-Id": "<20210909094849.313936-3-u.kleine-koenig@pengutronix.de>", "X-Mailer": "git-send-email 2.30.2", "In-Reply-To": "<20210909094849.313936-1-u.kleine-koenig@pengutronix.de>", "References": "<20210909094849.313936-1-u.kleine-koenig@pengutronix.de>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "X-Patch-Hashes": "v=1; h=sha256; i=ADb3X3G6cTKGPLEU01jqBnEkf1z6W7XmJPr+ak+as70=;\n m=cPi2oQpBA0UOP+uG776+b5rdTfkX0rEMvkiDpl7Te+w=;\n p=gRlwPJU6+GAk5P42OuTuFQ/D9TOrcwNWMwJfGz/vBAA=;\n g=92d5dd006f08fb17a9c8950685aabab037f5788b", "X-Patch-Sig": "m=pgp; i=u.kleine-koenig@pengutronix.de;\n s=0x0D2511F322BFAB1C1580266BE2DCDD9132669BD6;\n b=iQEzBAABCgAdFiEEfnIqFpAYrP8+dKQLwfwUeK3K7AkFAmE52H0ACgkQwfwUeK3K7AnQiQf/ZvA\n 4Boli3XKtSRU7GU0j5HVOCduLQCF6IZaISUPpV593q8o/UV+Akbtd1t5jyU/dAv0xiwOkdHZdJPVS\n dkM7mx/7SLPMtBH/S8YNY7xBsfZ0w2ZTx43PPfcR2rRKAms27uSICf8MO52owuC2PcLZSyeZnDdrX\n 4coFLRRfR+EP43SMvrNvMEZaYKgB8v4L5fWuPFpkYW5jMBaywUlbS69+dPLDJNdIznfhSnNp+P2ab\n rxGOGQ+ILUrLYgrlqCZW3DFxN1xzSZgg+D+5DxhXmp3MkNigwKfyGZHczUm/qGvL0hqjpGN4h0zzt\n o3ojcf5+gj/ynwYYqrDHh58+BWMCXwQ==", "Content-Transfer-Encoding": "8bit", "X-SA-Exim-Connect-IP": "2a0a:edc0:0:c01:1d::a2", "X-SA-Exim-Mail-From": "ukl@pengutronix.de", "X-SA-Exim-Scanned": "No (on metis.ext.pengutronix.de);\n SAEximRunCond expanded to false", "X-PTX-Original-Recipient": "linux-pwm@vger.kernel.org", "Precedence": "bulk", "List-ID": "<linux-pwm.vger.kernel.org>", "X-Mailing-List": "linux-pwm@vger.kernel.org" }, "content": "At least some implementations sleep. So mark pwm_apply_state() with a\nmight_sleep() to make callers aware. In the worst case this uncovers a\nvalid atomic user, then we revert this patch and at least gained some more\nknowledge and then can work on a concept similar to\ngpio_get_value/gpio_get_value_cansleep.\n\nSigned-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>\n---\n drivers/pwm/core.c | 9 +++++++++\n include/linux/pwm.h | 4 ++++\n 2 files changed, 13 insertions(+)", "diff": "diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c\nindex 4527f09a5c50..b7cda8a3eb85 100644\n--- a/drivers/pwm/core.c\n+++ b/drivers/pwm/core.c\n@@ -532,6 +532,15 @@ int pwm_apply_state(struct pwm_device *pwm, const struct pwm_state *state)\n \tstruct pwm_chip *chip;\n \tint err;\n \n+\t/*\n+\t * Some lowlevel driver's implementations of .apply() make use of\n+\t * mutexes, also with some drivers only returning when the new\n+\t * configuration is active calling pwm_apply_state() from atomic context\n+\t * is a bad idea. So make it explict that calling this function might\n+\t * sleep.\n+\t */\n+\tmight_sleep();\n+\n \tif (!pwm || !state || !state->period ||\n \t state->duty_cycle > state->period)\n \t\treturn -EINVAL;\ndiff --git a/include/linux/pwm.h b/include/linux/pwm.h\nindex 515e33978e97..e6dac95e4960 100644\n--- a/include/linux/pwm.h\n+++ b/include/linux/pwm.h\n@@ -441,6 +441,7 @@ static inline void pwm_free(struct pwm_device *pwm)\n static inline int pwm_apply_state(struct pwm_device *pwm,\n \t\t\t\t const struct pwm_state *state)\n {\n+\tmight_sleep();\n \treturn -ENOTSUPP;\n }\n \n@@ -452,6 +453,7 @@ static inline int pwm_adjust_config(struct pwm_device *pwm)\n static inline int pwm_config(struct pwm_device *pwm, int duty_ns,\n \t\t\t int period_ns)\n {\n+\tmight_sleep();\n \treturn -EINVAL;\n }\n \n@@ -464,11 +466,13 @@ static inline int pwm_capture(struct pwm_device *pwm,\n \n static inline int pwm_enable(struct pwm_device *pwm)\n {\n+\tmight_sleep();\n \treturn -EINVAL;\n }\n \n static inline void pwm_disable(struct pwm_device *pwm)\n {\n+\tmight_sleep();\n }\n \n static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)\n", "prefixes": [ "2/2" ] }