From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH v2] serial: uart: add hw flow control support configuration Date: Thu, 7 Aug 2014 13:24:02 -0400 Message-ID: <53E3B632.9050902@ti.com> References: <1398971093-17164-1-git-send-email-m-karicheri2@ti.com> <53E39B44.60406@hurleysoftware.com> <53E3A67B.6070709@ti.com> <20140807171254.GA13097@kroah.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from comal.ext.ti.com ([198.47.26.152]:53553 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757264AbaHGRY1 (ORCPT ); Thu, 7 Aug 2014 13:24:27 -0400 In-Reply-To: <20140807171254.GA13097@kroah.com> Sender: linux-serial-owner@vger.kernel.org List-Id: linux-serial@vger.kernel.org To: Greg Kroah-Hartman Cc: Peter Hurley , devicetree@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Randy Dunlap , Jiri Slaby , Santosh Shilimkar On 08/07/2014 01:12 PM, Greg Kroah-Hartman wrote: > On Thu, Aug 07, 2014 at 12:16:59PM -0400, Murali Karicheri wrote: >> On 08/07/2014 11:29 AM, Peter Hurley wrote: >>> On 05/01/2014 03:04 PM, Murali Karicheri wrote: >>>> 8250 uart driver currently supports only software assisted hw flow >>>> control. The software assisted hw flow control maintains a hw_stopped >>>> flag in the tty structure to stop and start transmission and use modem >>>> status interrupt for the event to drive the handshake signals. This is >>>> not needed if hw has flow control capabilities. This patch adds a >>>> DT attribute for enabling hw flow control for a uart port. Also skip >>>> stop and start if this flag is present in flag field of the port >>>> structure. >>>> >>>> Signed-off-by: Murali Karicheri >>>> >>>> CC: Rob Herring >>>> CC: Pawel Moll >>>> CC: Mark Rutland >>>> CC: Ian Campbell >>>> CC: Kumar Gala >>>> CC: Randy Dunlap >>>> CC: Greg Kroah-Hartman >>>> CC: Jiri Slaby >>>> CC: Santosh Shilimkar >>>> --- >>>> .../devicetree/bindings/serial/of-serial.txt | 1 + >>>> drivers/tty/serial/8250/8250_core.c | 6 ++++-- >>>> drivers/tty/serial/of_serial.c | 4 ++++ >>>> drivers/tty/serial/serial_core.c | 12 +++++++++--- >>>> 4 files changed, 18 insertions(+), 5 deletions(-) >>>> >>> [...] >>> >>>> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c >>>> index b68550d..851707a 100644 >>>> --- a/drivers/tty/serial/serial_core.c >>>> +++ b/drivers/tty/serial/serial_core.c >>>> @@ -174,8 +174,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, >>>> if (tty->termios.c_cflag& CBAUD) >>>> uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR); >>>> } >>>> - >>>> - if (tty_port_cts_enabled(port)) { >>>> + /* >>>> + * if hw support flow control without software intervention, >>>> + * then skip the below check >>>> + */ >>>> + if (tty_port_cts_enabled(port)&& >>>> + !(uport->flags& UPF_HARD_FLOW)) { >>>> spin_lock_irq(&uport->lock); >>>> if (!(uport->ops->get_mctrl(uport)& TIOCM_CTS)) >>>> tty->hw_stopped = 1; >>>> @@ -2772,7 +2776,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) >>>> >>>> uport->icount.cts++; >>>> >>>> - if (tty_port_cts_enabled(port)) { >>>> + /* skip below code if the hw flow control is supported */ >>>> + if (tty_port_cts_enabled(port)&& >>>> + !(uport->flags& UPF_HARD_FLOW)) { >>> Why is a modem status interrupt being generated for DCTS >>> if autoflow control is enabled? >>> >>> This should be: >>> >>> WARN_ON_ONCE(uport->flags& UPF_HARD_FLOW); >>> >>> to indicate a mis-configured driver/device. >> This patch is already merged to the upstream branch and if you see any >> issue, please >> post a patch for review. > > If someone points out a problem in a patch of yours that is accepted > upstream, it is nice to provide a fix, otherwise I will just revert it > upstream, as it looks to be incorrect. > > So, should I just revert it? > > greg k-h Greg, Sorry, I misunderstood it. I think it would have been better to start a new thread to point this out. Anyways I will send out a patch to add this and please don't revert. Murali From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932501AbaHGRY3 (ORCPT ); Thu, 7 Aug 2014 13:24:29 -0400 Received: from comal.ext.ti.com ([198.47.26.152]:53553 "EHLO comal.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757264AbaHGRY1 (ORCPT ); Thu, 7 Aug 2014 13:24:27 -0400 Message-ID: <53E3B632.9050902@ti.com> Date: Thu, 7 Aug 2014 13:24:02 -0400 From: Murali Karicheri User-Agent: Mozilla/5.0 (X11; Linux i686; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 MIME-Version: 1.0 To: Greg Kroah-Hartman CC: Peter Hurley , , , , , Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Randy Dunlap , Jiri Slaby , Santosh Shilimkar Subject: Re: [PATCH v2] serial: uart: add hw flow control support configuration References: <1398971093-17164-1-git-send-email-m-karicheri2@ti.com> <53E39B44.60406@hurleysoftware.com> <53E3A67B.6070709@ti.com> <20140807171254.GA13097@kroah.com> In-Reply-To: <20140807171254.GA13097@kroah.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 08/07/2014 01:12 PM, Greg Kroah-Hartman wrote: > On Thu, Aug 07, 2014 at 12:16:59PM -0400, Murali Karicheri wrote: >> On 08/07/2014 11:29 AM, Peter Hurley wrote: >>> On 05/01/2014 03:04 PM, Murali Karicheri wrote: >>>> 8250 uart driver currently supports only software assisted hw flow >>>> control. The software assisted hw flow control maintains a hw_stopped >>>> flag in the tty structure to stop and start transmission and use modem >>>> status interrupt for the event to drive the handshake signals. This is >>>> not needed if hw has flow control capabilities. This patch adds a >>>> DT attribute for enabling hw flow control for a uart port. Also skip >>>> stop and start if this flag is present in flag field of the port >>>> structure. >>>> >>>> Signed-off-by: Murali Karicheri >>>> >>>> CC: Rob Herring >>>> CC: Pawel Moll >>>> CC: Mark Rutland >>>> CC: Ian Campbell >>>> CC: Kumar Gala >>>> CC: Randy Dunlap >>>> CC: Greg Kroah-Hartman >>>> CC: Jiri Slaby >>>> CC: Santosh Shilimkar >>>> --- >>>> .../devicetree/bindings/serial/of-serial.txt | 1 + >>>> drivers/tty/serial/8250/8250_core.c | 6 ++++-- >>>> drivers/tty/serial/of_serial.c | 4 ++++ >>>> drivers/tty/serial/serial_core.c | 12 +++++++++--- >>>> 4 files changed, 18 insertions(+), 5 deletions(-) >>>> >>> [...] >>> >>>> diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c >>>> index b68550d..851707a 100644 >>>> --- a/drivers/tty/serial/serial_core.c >>>> +++ b/drivers/tty/serial/serial_core.c >>>> @@ -174,8 +174,12 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, >>>> if (tty->termios.c_cflag& CBAUD) >>>> uart_set_mctrl(uport, TIOCM_RTS | TIOCM_DTR); >>>> } >>>> - >>>> - if (tty_port_cts_enabled(port)) { >>>> + /* >>>> + * if hw support flow control without software intervention, >>>> + * then skip the below check >>>> + */ >>>> + if (tty_port_cts_enabled(port)&& >>>> + !(uport->flags& UPF_HARD_FLOW)) { >>>> spin_lock_irq(&uport->lock); >>>> if (!(uport->ops->get_mctrl(uport)& TIOCM_CTS)) >>>> tty->hw_stopped = 1; >>>> @@ -2772,7 +2776,9 @@ void uart_handle_cts_change(struct uart_port *uport, unsigned int status) >>>> >>>> uport->icount.cts++; >>>> >>>> - if (tty_port_cts_enabled(port)) { >>>> + /* skip below code if the hw flow control is supported */ >>>> + if (tty_port_cts_enabled(port)&& >>>> + !(uport->flags& UPF_HARD_FLOW)) { >>> Why is a modem status interrupt being generated for DCTS >>> if autoflow control is enabled? >>> >>> This should be: >>> >>> WARN_ON_ONCE(uport->flags& UPF_HARD_FLOW); >>> >>> to indicate a mis-configured driver/device. >> This patch is already merged to the upstream branch and if you see any >> issue, please >> post a patch for review. > > If someone points out a problem in a patch of yours that is accepted > upstream, it is nice to provide a fix, otherwise I will just revert it > upstream, as it looks to be incorrect. > > So, should I just revert it? > > greg k-h Greg, Sorry, I misunderstood it. I think it would have been better to start a new thread to point this out. Anyways I will send out a patch to add this and please don't revert. Murali