| Message ID | 1438203535-38028-1-git-send-email-shenwei.wang@freescale.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Jul 29, 2015 at 5:58 PM, Shenwei Wang <shenwei.wang@freescale.com> wrote: > +static int imx_serial_port_suspend_noirq(struct device *dev) > +{ > + struct platform_device *pdev = to_platform_device(dev); > + struct imx_port *sport = platform_get_drvdata(pdev); > + > + /* Save necessary regs */ > + clk_enable(sport->clk_ipg); clk_enable() may fail, so you should check its return value. > + sport->saved_reg[0] = readl(sport->port.membase + UCR1); > + sport->saved_reg[1] = readl(sport->port.membase + UCR2); > + sport->saved_reg[2] = readl(sport->port.membase + UCR3); > + sport->saved_reg[3] = readl(sport->port.membase + UCR4); > + sport->saved_reg[4] = readl(sport->port.membase + UFCR); > + sport->saved_reg[5] = readl(sport->port.membase + UESC); > + sport->saved_reg[6] = readl(sport->port.membase + UTIM); > + sport->saved_reg[7] = readl(sport->port.membase + UBIR); > + sport->saved_reg[8] = readl(sport->port.membase + UBMR); > + sport->saved_reg[9] = readl(sport->port.membase + IMX21_UTS); > + clk_disable(sport->clk_ipg); > + > + dev_dbg(dev, "0x%p (%d)\r\n", sport->port.membase, sport->port.line); > + > + return 0; > +} > + > +static int imx_serial_port_resume_noirq(struct device *dev) > +{ > + struct platform_device *pdev = to_platform_device(dev); > + struct imx_port *sport = platform_get_drvdata(pdev); > + > + clk_enable(sport->clk_ipg); Same here. > + writel(sport->saved_reg[4], sport->port.membase + UFCR); > + writel(sport->saved_reg[5], sport->port.membase + UESC); > + writel(sport->saved_reg[6], sport->port.membase + UTIM); > + writel(sport->saved_reg[7], sport->port.membase + UBIR); > + writel(sport->saved_reg[8], sport->port.membase + UBMR); > + writel(sport->saved_reg[9], sport->port.membase + IMX21_UTS); > + writel(sport->saved_reg[0], sport->port.membase + UCR1); > + writel(sport->saved_reg[1] | 0x1, sport->port.membase + UCR2); Why this magic '| 0x1'? Can't you use a define instead?
> -----Original Message----- > From: Fabio Estevam [mailto:festevam@gmail.com] > Sent: 2015?7?29? 16:21 > To: Wang Shenwei-B38339 > Cc: Greg Kroah-Hartman; linux-arm-kernel@lists.infradead.org; > linux-serial@vger.kernel.org > Subject: Re: [PATCH v3 1/1] Serial: imx: add dev_pm_ops to support suspend to > ram/disk > > On Wed, Jul 29, 2015 at 5:58 PM, Shenwei Wang <shenwei.wang@freescale.com> > wrote: > > > +static int imx_serial_port_suspend_noirq(struct device *dev) { > > + struct platform_device *pdev = to_platform_device(dev); > > + struct imx_port *sport = platform_get_drvdata(pdev); > > + > > + /* Save necessary regs */ > > + clk_enable(sport->clk_ipg); > > clk_enable() may fail, so you should check its return value. The check seems a little superfluous because the failure condition for clk_enable is (clk == NULL || IS_ERR(clk)) Once this function is called which means the initialization of the driver is successful. > > + sport->saved_reg[0] = readl(sport->port.membase + UCR1); > > + sport->saved_reg[1] = readl(sport->port.membase + UCR2); > > + sport->saved_reg[2] = readl(sport->port.membase + UCR3); > > + sport->saved_reg[3] = readl(sport->port.membase + UCR4); > > + sport->saved_reg[4] = readl(sport->port.membase + UFCR); > > + sport->saved_reg[5] = readl(sport->port.membase + UESC); > > + sport->saved_reg[6] = readl(sport->port.membase + UTIM); > > + sport->saved_reg[7] = readl(sport->port.membase + UBIR); > > + sport->saved_reg[8] = readl(sport->port.membase + UBMR); > > + sport->saved_reg[9] = readl(sport->port.membase + IMX21_UTS); > > + clk_disable(sport->clk_ipg); > > + > > + dev_dbg(dev, "0x%p (%d)\r\n", sport->port.membase, > > + sport->port.line); > > + > > + return 0; > > +} > > + > > +static int imx_serial_port_resume_noirq(struct device *dev) { > > + struct platform_device *pdev = to_platform_device(dev); > > + struct imx_port *sport = platform_get_drvdata(pdev); > > + > > + clk_enable(sport->clk_ipg); > > Same here. > > > + writel(sport->saved_reg[4], sport->port.membase + UFCR); > > + writel(sport->saved_reg[5], sport->port.membase + UESC); > > + writel(sport->saved_reg[6], sport->port.membase + UTIM); > > + writel(sport->saved_reg[7], sport->port.membase + UBIR); > > + writel(sport->saved_reg[8], sport->port.membase + UBMR); > > + writel(sport->saved_reg[9], sport->port.membase + IMX21_UTS); > > + writel(sport->saved_reg[0], sport->port.membase + UCR1); > > + writel(sport->saved_reg[1] | 0x1, sport->port.membase + UCR2); > > Why this magic '| 0x1'? Can't you use a define instead? Yes, should be a macro. Thanks, Shenwei
On Wed, Jul 29, 2015 at 6:41 PM, Shenwei Wang <Shenwei.Wang@freescale.com> wrote: >> clk_enable() may fail, so you should check its return value. > > The check seems a little superfluous because the failure condition for clk_enable is > (clk == NULL || IS_ERR(clk)) > Once this function is called which means the initialization of the driver is successful. Not superfluos. You can't assume that clk_enable() will always be successful. Better check its return value.
> -----Original Message----- > From: Fabio Estevam [mailto:festevam@gmail.com] > Sent: 2015?7?29? 16:46 > To: Wang Shenwei-B38339 > Cc: Greg Kroah-Hartman; linux-arm-kernel@lists.infradead.org; > linux-serial@vger.kernel.org > Subject: Re: [PATCH v3 1/1] Serial: imx: add dev_pm_ops to support suspend to > ram/disk > > On Wed, Jul 29, 2015 at 6:41 PM, Shenwei Wang <Shenwei.Wang@freescale.com> > wrote: > > >> clk_enable() may fail, so you should check its return value. > > > > The check seems a little superfluous because the failure condition for > > clk_enable is (clk == NULL || IS_ERR(clk)) Once this function is > > called which means the initialization of the driver is successful. > > Not superfluos. You can't assume that clk_enable() will always be successful. > Better check its return value. I am very interesting to know if you could provide an example condition that may cause clk_enable failed in this callback function? Regards, Shenwei
On Wed, Jul 29, 2015 at 6:54 PM, Shenwei Wang <Shenwei.Wang@freescale.com> wrote: > I am very interesting to know if you could provide an example condition that may cause > clk_enable failed in this callback function? Let's check clk_enable definition: int clk_enable(struct clk *clk) { unsigned long flags; int ret; if (!clk) return 0; flags = clk_enable_lock(); ret = clk_core_enable(clk->core); clk_enable_unlock(flags); return ret; } So if I see it right it returns 'int' not 'void' ;-)
> -----Original Message----- > From: Fabio Estevam [mailto:festevam@gmail.com] > Sent: 2015?7?29? 17:11 > To: Wang Shenwei-B38339 > Cc: Greg Kroah-Hartman; linux-arm-kernel@lists.infradead.org; > linux-serial@vger.kernel.org > Subject: Re: [PATCH v3 1/1] Serial: imx: add dev_pm_ops to support suspend to > ram/disk > > On Wed, Jul 29, 2015 at 6:54 PM, Shenwei Wang <Shenwei.Wang@freescale.com> > wrote: > > > I am very interesting to know if you could provide an example > > condition that may cause clk_enable failed in this callback function? > > Let's check clk_enable definition: > > int clk_enable(struct clk *clk) > { > unsigned long flags; > int ret; > > if (!clk) > return 0; > > flags = clk_enable_lock(); > ret = clk_core_enable(clk->core); > clk_enable_unlock(flags); > > return ret; > } > > So if I see it right it returns 'int' not 'void' ;-) Actually, the function shows even if it is in error status like the parameter "clk" is null the return value is zero. Inside the function "clk_core_enable", if everything goes smooth, it still returns zero. Moreover, this patch does not care about the return value of clk_enable, whatever value it returns, the following codes keep the same. Regards, Shenwei
Hi, > > -----Original Message----- > > From: Fabio Estevam [mailto:festevam@gmail.com] > > Sent: 2015?7?29? 17:11 > > To: Wang Shenwei-B38339 > > Cc: Greg Kroah-Hartman; linux-arm-kernel@lists.infradead.org; > > linux-serial@vger.kernel.org > > Subject: Re: [PATCH v3 1/1] Serial: imx: add dev_pm_ops to support suspend to > > ram/disk > > > > On Wed, Jul 29, 2015 at 6:54 PM, Shenwei Wang <Shenwei.Wang@freescale.com> > > wrote: > > > > > I am very interesting to know if you could provide an example > > > condition that may cause clk_enable failed in this callback function? > > > > Let's check clk_enable definition: > > > > int clk_enable(struct clk *clk) > > { > > unsigned long flags; > > int ret; > > > > if (!clk) > > return 0; > > > > flags = clk_enable_lock(); > > ret = clk_core_enable(clk->core); > > clk_enable_unlock(flags); > > > > return ret; > > } > > > > So if I see it right it returns 'int' not 'void' ;-) > > Actually, the function shows even if it is in error status like the parameter "clk" is null the return value is zero. > Inside the function "clk_core_enable", if everything goes smooth, it still returns zero. > A NULL clk is a valid clk per definition. > Moreover, this patch does not care about the return value of clk_enable, whatever value it returns, the following codes keep > the same. > Nevertheless it would be good to inform the user of a failure, since that may affect the system's stability after returning from suspend. Even if the current implementation of a function cannot return an error code in some specific circumstance, that doesn't mean that this will be always the case. Thus, checking the return code and acting upon it is always advisable. Lothar Waßmann
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 2c90dc3..10dece3 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -216,6 +216,7 @@ struct imx_port { unsigned int tx_bytes; unsigned int dma_tx_nents; wait_queue_head_t dma_wait; + unsigned int saved_reg[10]; }; struct imx_port_ucrs { @@ -1811,36 +1812,6 @@ static struct uart_driver imx_reg = { .cons = IMX_CONSOLE, }; -static int serial_imx_suspend(struct platform_device *dev, pm_message_t state) -{ - struct imx_port *sport = platform_get_drvdata(dev); - unsigned int val; - - /* enable wakeup from i.MX UART */ - val = readl(sport->port.membase + UCR3); - val |= UCR3_AWAKEN; - writel(val, sport->port.membase + UCR3); - - uart_suspend_port(&imx_reg, &sport->port); - - return 0; -} - -static int serial_imx_resume(struct platform_device *dev) -{ - struct imx_port *sport = platform_get_drvdata(dev); - unsigned int val; - - /* disable wakeup from i.MX UART */ - val = readl(sport->port.membase + UCR3); - val &= ~UCR3_AWAKEN; - writel(val, sport->port.membase + UCR3); - - uart_resume_port(&imx_reg, &sport->port); - - return 0; -} - #ifdef CONFIG_OF /* * This function returns 1 iff pdev isn't a device instatiated by dt, 0 iff it @@ -1992,16 +1963,101 @@ static int serial_imx_remove(struct platform_device *pdev) return uart_remove_one_port(&imx_reg, &sport->port); } +static int imx_serial_port_suspend_noirq(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct imx_port *sport = platform_get_drvdata(pdev); + + /* Save necessary regs */ + clk_enable(sport->clk_ipg); + sport->saved_reg[0] = readl(sport->port.membase + UCR1); + sport->saved_reg[1] = readl(sport->port.membase + UCR2); + sport->saved_reg[2] = readl(sport->port.membase + UCR3); + sport->saved_reg[3] = readl(sport->port.membase + UCR4); + sport->saved_reg[4] = readl(sport->port.membase + UFCR); + sport->saved_reg[5] = readl(sport->port.membase + UESC); + sport->saved_reg[6] = readl(sport->port.membase + UTIM); + sport->saved_reg[7] = readl(sport->port.membase + UBIR); + sport->saved_reg[8] = readl(sport->port.membase + UBMR); + sport->saved_reg[9] = readl(sport->port.membase + IMX21_UTS); + clk_disable(sport->clk_ipg); + + dev_dbg(dev, "0x%p (%d)\r\n", sport->port.membase, sport->port.line); + + return 0; +} + +static int imx_serial_port_resume_noirq(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct imx_port *sport = platform_get_drvdata(pdev); + + clk_enable(sport->clk_ipg); + writel(sport->saved_reg[4], sport->port.membase + UFCR); + writel(sport->saved_reg[5], sport->port.membase + UESC); + writel(sport->saved_reg[6], sport->port.membase + UTIM); + writel(sport->saved_reg[7], sport->port.membase + UBIR); + writel(sport->saved_reg[8], sport->port.membase + UBMR); + writel(sport->saved_reg[9], sport->port.membase + IMX21_UTS); + writel(sport->saved_reg[0], sport->port.membase + UCR1); + writel(sport->saved_reg[1] | 0x1, sport->port.membase + UCR2); + writel(sport->saved_reg[2], sport->port.membase + UCR3); + writel(sport->saved_reg[3], sport->port.membase + UCR4); + clk_disable(sport->clk_ipg); + + dev_dbg(dev, "0x%p (%d)\r\n", sport->port.membase, sport->port.line); + + return 0; +} + +static int imx_serial_port_suspend(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct imx_port *sport = platform_get_drvdata(pdev); + unsigned int val; + + /* enable wakeup from i.MX UART */ + val = readl(sport->port.membase + UCR3); + val |= UCR3_AWAKEN; + writel(val, sport->port.membase + UCR3); + + uart_suspend_port(&imx_reg, &sport->port); + + return 0; +} + +static int imx_serial_port_resume(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + struct imx_port *sport = platform_get_drvdata(pdev); + unsigned int val; + + /* disable wakeup from i.MX UART */ + val = readl(sport->port.membase + UCR3); + val &= ~UCR3_AWAKEN; + writel(val, sport->port.membase + UCR3); + + uart_resume_port(&imx_reg, &sport->port); + + return 0; +} + +static const struct dev_pm_ops imx_serial_port_pm_ops = { + .suspend_noirq = imx_serial_port_suspend_noirq, + .resume_noirq = imx_serial_port_resume_noirq, + .suspend = imx_serial_port_suspend, + .resume = imx_serial_port_resume, +}; + static struct platform_driver serial_imx_driver = { .probe = serial_imx_probe, .remove = serial_imx_remove, - .suspend = serial_imx_suspend, - .resume = serial_imx_resume, .id_table = imx_uart_devtype, .driver = { .name = "imx-uart", .of_match_table = imx_uart_dt_ids, + .pm = &imx_serial_port_pm_ops, }, };
When system goes into low power states like SUSPEND_MEM and HIBERNATION, the hardware IP block may be powered off to reduce the power consumption. This power down may cause problems on some imx platforms, because the hardware settings are reset to its power on default values which may differ from the ones when it power off. This patch added the dev_pm_ops and implemented two callbacks: suspend_noirq and resume_noirq, which will save the necessory hardware parameters right before power down and recover them before system uses the hardware. Because added the dev_pm_ops, the old suspend/resume callbacks under platform_driver will not be called any more. Changed their prototypes and moved those two callbacks into dev_pm_ops too. Signed-off-by: Shenwei Wang <shenwei.wang@freescale.com> --- Change log: PATCH v3 After added the dev_pm_ops, the old suspend/resume callbacks under platform_driver will not be called. Changed their prototypes and moved them into dev_pm_ops too. PATCH v2 Change pr_debug to dev_dbg per GregK's review feedback. drivers/tty/serial/imx.c | 120 ++++++++++++++++++++++++++++++++++------------- 1 file changed, 88 insertions(+), 32 deletions(-) -- 2.5.0.rc2