[PATCH] tty: serial: msm: Remove duplicate handling of clocks

[PATCH] tty: serial: msm: Remove duplicate handling of clocks

[Pramod Gurav]

msm_serial driver provides a .pm callback to the serial core to enable
and disable clock resource in suspend/resume path. This function is
also called before msm_startup. msm_startup also enables the clocks which
is not needed. Hence remove the duplcate clock operation from msm_startup
and msm_shutdown. Same is done in console setup to get rid of duplicate
clock operation.

Tested on DB410C console.

Signed-off-by: Pramod Gurav <pramod.gurav@linaro.org>
---
 drivers/tty/serial/msm_serial.c | 15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index dcde955..73c3217 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -959,15 +959,6 @@ static int msm_set_baud_rate(struct uart_port *port, unsigned int baud,
 	return baud;
 }
 
-static void msm_init_clock(struct uart_port *port)
-{
-	struct msm_port *msm_port = UART_TO_MSM(port);
-
-	clk_prepare_enable(msm_port->clk);
-	clk_prepare_enable(msm_port->pclk);
-	msm_serial_set_mnd_regs(port);
-}
-
 static int msm_startup(struct uart_port *port)
 {
 	struct msm_port *msm_port = UART_TO_MSM(port);
@@ -982,7 +973,7 @@ static int msm_startup(struct uart_port *port)
 	if (unlikely(ret))
 		return ret;
 
-	msm_init_clock(port);
+	msm_serial_set_mnd_regs(port);
 
 	if (likely(port->fifosize > 12))
 		rfr_level = port->fifosize - 12;
@@ -1021,8 +1012,6 @@ static void msm_shutdown(struct uart_port *port)
 	if (msm_port->is_uartdm)
 		msm_release_dma(msm_port);
 
-	clk_disable_unprepare(msm_port->clk);
-
 	free_irq(port->irq, port);
 }
 
@@ -1451,7 +1440,7 @@ static int __init msm_console_setup(struct console *co, char *options)
 	if (unlikely(!port->membase))
 		return -ENXIO;
 
-	msm_init_clock(port);
+	msm_serial_set_mnd_regs(port);
 
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
-- 
1.8.2.1

Re: [PATCH] tty: serial: msm: Remove duplicate handling of clocks

[Stephen Boyd]

On 05/11, Pramod Gurav wrote:
> msm_serial driver provides a .pm callback to the serial core to enable
> and disable clock resource in suspend/resume path. This function is
> also called before msm_startup. msm_startup also enables the clocks which
> is not needed. Hence remove the duplcate clock operation from msm_startup
> and msm_shutdown. Same is done in console setup to get rid of duplicate
> clock operation.

I had to check and I see that for the console case we call the
.pm callback and don't turn it off until suspend/resume paths
(would be nice to add suspend/resume to this driver too). I
guess that's what you meant by this last sentence?

> 
> Tested on DB410C console.
> 
> Signed-off-by: Pramod Gurav <pramod.gurav@linaro.org>

Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

Re: [PATCH] tty: serial: msm: Remove duplicate handling of clocks

[Pramod Gurav]

On 12 May 2016 at 05:48, Stephen Boyd <sboyd@codeaurora.org> wrote:
> On 05/11, Pramod Gurav wrote:
>> msm_serial driver provides a .pm callback to the serial core to enable
>> and disable clock resource in suspend/resume path. This function is
>> also called before msm_startup. msm_startup also enables the clocks which
>> is not needed. Hence remove the duplcate clock operation from msm_startup
>> and msm_shutdown. Same is done in console setup to get rid of duplicate
>> clock operation.
>
> I had to check and I see that for the console case we call the
> .pm callback and don't turn it off until suspend/resume paths
> (would be nice to add suspend/resume to this driver too). I
> guess that's what you meant by this last sentence?
>
Yes the clocks would be kept ON if its console.
I am working to add suspend/resume and runtime pm as it will not
happen by default through core.
>>
>> Tested on DB410C console.
>>
>> Signed-off-by: Pramod Gurav <pramod.gurav@linaro.org>
>
> Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
>
> --
> Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> a Linux Foundation Collaborative Project

Re: [PATCH] tty: serial: msm: Remove duplicate handling of clocks

[Pramod Gurav]

On 11 May 2016 at 14:30, Pramod Gurav <pramod.gurav@linaro.org> wrote:
> msm_serial driver provides a .pm callback to the serial core to enable
> and disable clock resource in suspend/resume path. This function is
> also called before msm_startup. msm_startup also enables the clocks which
> is not needed. Hence remove the duplcate clock operation from msm_startup
> and msm_shutdown. Same is done in console setup to get rid of duplicate
> clock operation.
>
> Tested on DB410C console.
>
> Signed-off-by: Pramod Gurav <pramod.gurav@linaro.org>
> ---
>  drivers/tty/serial/msm_serial.c | 15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
> index dcde955..73c3217 100644
> --- a/drivers/tty/serial/msm_serial.c
> +++ b/drivers/tty/serial/msm_serial.c
> @@ -959,15 +959,6 @@ static int msm_set_baud_rate(struct uart_port *port, unsigned int baud,
>         return baud;
>  }
>
> -static void msm_init_clock(struct uart_port *port)
> -{
> -       struct msm_port *msm_port = UART_TO_MSM(port);
> -
> -       clk_prepare_enable(msm_port->clk);
> -       clk_prepare_enable(msm_port->pclk);
> -       msm_serial_set_mnd_regs(port);
> -}
> -
>  static int msm_startup(struct uart_port *port)
>  {
>         struct msm_port *msm_port = UART_TO_MSM(port);
> @@ -982,7 +973,7 @@ static int msm_startup(struct uart_port *port)
>         if (unlikely(ret))
>                 return ret;
>
> -       msm_init_clock(port);
> +       msm_serial_set_mnd_regs(port);

Further testing with another UART port made me realize that serial
port does not work after disabling msm_port->clk clock. The RX data
part will be affected.
Confirmed from manual that this clock should never be turned of to
avoid loss of incoming data. Sorry for the noise.

>
>         if (likely(port->fifosize > 12))
>                 rfr_level = port->fifosize - 12;
> @@ -1021,8 +1012,6 @@ static void msm_shutdown(struct uart_port *port)
>         if (msm_port->is_uartdm)
>                 msm_release_dma(msm_port);
>
> -       clk_disable_unprepare(msm_port->clk);
> -
>         free_irq(port->irq, port);
>  }
>
> @@ -1451,7 +1440,7 @@ static int __init msm_console_setup(struct console *co, char *options)
>         if (unlikely(!port->membase))
>                 return -ENXIO;
>
> -       msm_init_clock(port);
> +       msm_serial_set_mnd_regs(port);
>
>         if (options)
>                 uart_parse_options(options, &baud, &parity, &bits, &flow);
> --
> 1.8.2.1
>

Re: [PATCH] tty: serial: msm: Remove duplicate handling of clocks

[Stephen Boyd]

On 05/16, Pramod Gurav wrote:
> On 11 May 2016 at 14:30, Pramod Gurav <pramod.gurav@linaro.org> wrote:
> > msm_serial driver provides a .pm callback to the serial core to enable
> > and disable clock resource in suspend/resume path. This function is
> > also called before msm_startup. msm_startup also enables the clocks which
> > is not needed. Hence remove the duplcate clock operation from msm_startup
> > and msm_shutdown. Same is done in console setup to get rid of duplicate
> > clock operation.
> >
> > Tested on DB410C console.
> >
> > Signed-off-by: Pramod Gurav <pramod.gurav@linaro.org>
> > ---
> >  drivers/tty/serial/msm_serial.c | 15 ++-------------
> >  1 file changed, 2 insertions(+), 13 deletions(-)
> >
> > diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
> > index dcde955..73c3217 100644
> > --- a/drivers/tty/serial/msm_serial.c
> > +++ b/drivers/tty/serial/msm_serial.c
> > @@ -959,15 +959,6 @@ static int msm_set_baud_rate(struct uart_port *port, unsigned int baud,
> >         return baud;
> >  }
> >
> > -static void msm_init_clock(struct uart_port *port)
> > -{
> > -       struct msm_port *msm_port = UART_TO_MSM(port);
> > -
> > -       clk_prepare_enable(msm_port->clk);
> > -       clk_prepare_enable(msm_port->pclk);
> > -       msm_serial_set_mnd_regs(port);
> > -}
> > -
> >  static int msm_startup(struct uart_port *port)
> >  {
> >         struct msm_port *msm_port = UART_TO_MSM(port);
> > @@ -982,7 +973,7 @@ static int msm_startup(struct uart_port *port)
> >         if (unlikely(ret))
> >                 return ret;
> >
> > -       msm_init_clock(port);
> > +       msm_serial_set_mnd_regs(port);
> 
> Further testing with another UART port made me realize that serial
> port does not work after disabling msm_port->clk clock. The RX data
> part will be affected.
> Confirmed from manual that this clock should never be turned of to
> avoid loss of incoming data. Sorry for the noise.
> 

Does that mean this patch shouldn't be applied? I hope that the
pm callback would do the right thing and be called when we expect
to be receiving data on the line.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project