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Tue, 08 Oct 2019 13:41:50 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 831D710002A; Tue, 8 Oct 2019 13:41:47 +0200 (CEST) Received: from Webmail-eu.st.com (Safex1hubcas21.st.com [10.75.90.44]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 766142B8A64; Tue, 8 Oct 2019 13:41:47 +0200 (CEST) Received: from SAFEX1HUBCAS23.st.com (10.75.90.46) by SAFEX1HUBCAS21.st.com (10.75.90.44) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 8 Oct 2019 13:41:47 +0200 Received: from localhost (10.48.0.192) by webmail-ga.st.com (10.75.90.48) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 8 Oct 2019 13:41:46 +0200 From: Fabrice Gasnier To: , Subject: [PATCH] pwm: stm32: add comment to better describe breakinput feature Date: Tue, 8 Oct 2019 13:41:27 +0200 Message-ID: <1570534887-26181-1-git-send-email-fabrice.gasnier@st.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.48.0.192] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,1.0.8 definitions=2019-10-08_04:2019-10-08,2019-10-08 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191008_044155_050755_C6EB7B43 X-CRM114-Status: GOOD ( 13.71 ) X-Spam-Score: -0.9 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at https://www.dnswl.org/, low trust [62.209.51.94 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pwm@vger.kernel.org, alexandre.torgue@st.com, linux-kernel@vger.kernel.org, fabrice.gasnier@st.com, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, benjamin.gaignard@st.com Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org Add a comment to better describe the purpose of breakinput feature that can be found on some STM32 timer instances. Briefly comment on the characteristics of this input for PWM, and pinmuxing as suggested in [1]. [1] https://lkml.org/lkml/2019/10/1/207 Signed-off-by: Fabrice Gasnier --- drivers/pwm/pwm-stm32.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/drivers/pwm/pwm-stm32.c b/drivers/pwm/pwm-stm32.c index 359b085..6406ebb 100644 --- a/drivers/pwm/pwm-stm32.c +++ b/drivers/pwm/pwm-stm32.c @@ -522,8 +522,14 @@ static int stm32_pwm_apply_breakinputs(struct stm32_pwm *priv, sizeof(struct stm32_breakinput)); /* + * Some timer instances can have BRK input pins (e.g. basically a fault + * pin from the output power stage). The break feature allows a safe + * shut-down of the PWM outputs to a predefined state. Further details + * are available in application note AN4277, "Using STM32 device PWM + * shut-down features..." * Because "st,breakinput" parameter is optional do not make probe - * failed if it doesn't exist. + * failed if it doesn't exist. The pinctrl handle must hold the BRK + * pin(s) when using "st,breakinput" property. */ if (nb <= 0) return 0;