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[72.194.116.95]) by smtp.gmail.com with ESMTPSA id r8-20020a05620a298800b006b4689e3425sm2270630qkp.129.2022.07.04.08.35.59 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 04 Jul 2022 08:36:00 -0700 (PDT) Message-ID: Date: Mon, 4 Jul 2022 08:35:57 -0700 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.0 Subject: Re: [PATCH v2] serial: 8250_bcm7271: Save/restore RTS in suspend/resume Content-Language: en-US To: Jiri Slaby , Florian Fainelli , linux-serial@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Doug Berger , Al Cooper , Broadcom internal kernel review list , Greg Kroah-Hartman References: <20220629160208.3167955-1-f.fainelli@gmail.com> From: Florian Fainelli In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/3/2022 11:40 PM, Jiri Slaby wrote: > On 29. 06. 22, 18:02, Florian Fainelli wrote: >> From: Doug Berger >> >> Commit 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming >> from S2") prevented an early enabling of RTS during resume, but it did >> not actively restore the RTS state after resume. >> >> Fixes: 9cabe26e65a8 ("serial: 8250_bcm7271: UART errors after resuming >> from S2") >> Signed-off-by: Doug Berger >> Signed-off-by: Florian Fainelli >> --- >>   drivers/tty/serial/8250/8250_bcm7271.c | 24 ++++++++++++++++++------ >>   1 file changed, 18 insertions(+), 6 deletions(-) >> >> diff --git a/drivers/tty/serial/8250/8250_bcm7271.c >> b/drivers/tty/serial/8250/8250_bcm7271.c >> index 9b878d023dac..b9cea38c8aff 100644 >> --- a/drivers/tty/serial/8250/8250_bcm7271.c >> +++ b/drivers/tty/serial/8250/8250_bcm7271.c > ... >> @@ -1180,7 +1184,15 @@ static int __maybe_unused >> brcmuart_resume(struct device *dev) >>           start_rx_dma(serial8250_get_port(priv->line)); >>       } >>       serial8250_resume_port(priv->line); >> -    port->mctrl = priv->saved_mctrl; >> + >> +    if (priv->saved_mctrl & TIOCM_RTS) { >> +        /* Restore RTS */ >> +        spin_lock_irqsave(&port->lock, flags); >> +        port->mctrl |= TIOCM_RTS; >> +        spin_unlock_irqrestore(&port->lock, flags); >> +        port->ops->set_mctrl(port, port->mctrl); > > Calling ->set_mctrl w/o port->lock doesn't look really safe. Good point, I will check with Doug whether this was intentional and if so, why, and if not why should we move it up under the spinlock. Thanks! -- Florian