| Message ID | 20220816043643.26569-4-alice.guo@oss.nxp.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | watchdog: imx7ulp_wdt: update i.MX7ULP WDOG timer driver | expand |
On Tue, Aug 16, 2022 at 12:36:39PM +0800, Alice Guo (OSS) wrote: > From: Ye Li <ye.li@nxp.com> > > When bootloader has enabled the CMD32EN bit, switch to use 32bits > unlock command to unlock the CS register. Using 32bits command will > help on avoiding 16 bus cycle window violation for two 16 bits > commands. > > Signed-off-by: Ye Li <ye.li@nxp.com> > Signed-off-by: Alice Guo <alice.guo@nxp.com> > Reviewed-by: Jacky Bai <ping.bai@nxp.com> > Acked-by: Jason Liu <jason.hui.liu@nxp.com> > --- > drivers/watchdog/imx7ulp_wdt.c | 15 ++++++++++----- > 1 file changed, 10 insertions(+), 5 deletions(-) > > diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c > index b8ac0cb04d2f..a0f6b8cea78f 100644 > --- a/drivers/watchdog/imx7ulp_wdt.c > +++ b/drivers/watchdog/imx7ulp_wdt.c > @@ -180,11 +180,16 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout) > > local_irq_disable(); > > - mb(); > - /* unlock the wdog for reconfiguration */ > - writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > - writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > - mb(); > + val = readl(base + WDOG_CS); > + if (val & WDOG_CS_CMD32EN) { > + writel(UNLOCK, base + WDOG_CNT); > + } else { > + mb(); > + /* unlock the wdog for reconfiguration */ > + writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > + writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > + mb(); Now this is intermixing writel() with writel_relaxed(), making the code all but impossible to understand. Guenter > + } > > ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); > if (ret) > -- > 2.17.1 >
> -----Original Message----- > From: Guenter Roeck <groeck7@gmail.com> On Behalf Of Guenter Roeck > Sent: Monday, August 22, 2022 10:06 PM > To: Alice Guo (OSS) <alice.guo@oss.nxp.com> > Cc: wim@linux-watchdog.org; shawnguo@kernel.org; > s.hauer@pengutronix.de; festevam@gmail.com; kernel@pengutronix.de; > dl-linux-imx <linux-imx@nxp.com>; linux-watchdog@vger.kernel.org; > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH 3/7] watchdog: imx7ulp_wdt: Check CMD32EN in wdog > init > > On Tue, Aug 16, 2022 at 12:36:39PM +0800, Alice Guo (OSS) wrote: > > From: Ye Li <ye.li@nxp.com> > > > > When bootloader has enabled the CMD32EN bit, switch to use 32bits > > unlock command to unlock the CS register. Using 32bits command will > > help on avoiding 16 bus cycle window violation for two 16 bits > > commands. > > > > Signed-off-by: Ye Li <ye.li@nxp.com> > > Signed-off-by: Alice Guo <alice.guo@nxp.com> > > Reviewed-by: Jacky Bai <ping.bai@nxp.com> > > Acked-by: Jason Liu <jason.hui.liu@nxp.com> > > --- > > drivers/watchdog/imx7ulp_wdt.c | 15 ++++++++++----- > > 1 file changed, 10 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/watchdog/imx7ulp_wdt.c > > b/drivers/watchdog/imx7ulp_wdt.c index b8ac0cb04d2f..a0f6b8cea78f > > 100644 > > --- a/drivers/watchdog/imx7ulp_wdt.c > > +++ b/drivers/watchdog/imx7ulp_wdt.c > > @@ -180,11 +180,16 @@ static int imx7ulp_wdt_init(void __iomem *base, > > unsigned int timeout) > > > > local_irq_disable(); > > > > - mb(); > > - /* unlock the wdog for reconfiguration */ > > - writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > > - writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > > - mb(); > > + val = readl(base + WDOG_CS); > > + if (val & WDOG_CS_CMD32EN) { > > + writel(UNLOCK, base + WDOG_CNT); > > + } else { > > + mb(); > > + /* unlock the wdog for reconfiguration */ > > + writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > > + writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > > + mb(); > > Now this is intermixing writel() with writel_relaxed(), making the code all but > impossible to understand. > > Guenter Hi Guenter, Intermixing writel() with writel_relaxed() is unavoidable here. Because there cannot be a memory barrier between writing UNLOCK_SEQ0 and writing UNLOCK_SEQ1. This may be determined by hardware design. Best Regards, Alice Guo > > + } > > > > ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); > > if (ret) > > -- > > 2.17.1 > >
On Tue, Aug 23, 2022 at 05:46:55AM +0000, Alice Guo (OSS) wrote: > > > > -----Original Message----- > > From: Guenter Roeck <groeck7@gmail.com> On Behalf Of Guenter Roeck > > Sent: Monday, August 22, 2022 10:06 PM > > To: Alice Guo (OSS) <alice.guo@oss.nxp.com> > > Cc: wim@linux-watchdog.org; shawnguo@kernel.org; > > s.hauer@pengutronix.de; festevam@gmail.com; kernel@pengutronix.de; > > dl-linux-imx <linux-imx@nxp.com>; linux-watchdog@vger.kernel.org; > > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org > > Subject: Re: [PATCH 3/7] watchdog: imx7ulp_wdt: Check CMD32EN in wdog > > init > > > > On Tue, Aug 16, 2022 at 12:36:39PM +0800, Alice Guo (OSS) wrote: > > > From: Ye Li <ye.li@nxp.com> > > > > > > When bootloader has enabled the CMD32EN bit, switch to use 32bits > > > unlock command to unlock the CS register. Using 32bits command will > > > help on avoiding 16 bus cycle window violation for two 16 bits > > > commands. > > > > > > Signed-off-by: Ye Li <ye.li@nxp.com> > > > Signed-off-by: Alice Guo <alice.guo@nxp.com> > > > Reviewed-by: Jacky Bai <ping.bai@nxp.com> > > > Acked-by: Jason Liu <jason.hui.liu@nxp.com> > > > --- > > > drivers/watchdog/imx7ulp_wdt.c | 15 ++++++++++----- > > > 1 file changed, 10 insertions(+), 5 deletions(-) > > > > > > diff --git a/drivers/watchdog/imx7ulp_wdt.c > > > b/drivers/watchdog/imx7ulp_wdt.c index b8ac0cb04d2f..a0f6b8cea78f > > > 100644 > > > --- a/drivers/watchdog/imx7ulp_wdt.c > > > +++ b/drivers/watchdog/imx7ulp_wdt.c > > > @@ -180,11 +180,16 @@ static int imx7ulp_wdt_init(void __iomem *base, > > > unsigned int timeout) > > > > > > local_irq_disable(); > > > > > > - mb(); > > > - /* unlock the wdog for reconfiguration */ > > > - writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > > > - writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > > > - mb(); > > > + val = readl(base + WDOG_CS); > > > + if (val & WDOG_CS_CMD32EN) { > > > + writel(UNLOCK, base + WDOG_CNT); > > > + } else { > > > + mb(); > > > + /* unlock the wdog for reconfiguration */ > > > + writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); > > > + writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); > > > + mb(); > > > > Now this is intermixing writel() with writel_relaxed(), making the code all but > > impossible to understand. > > > > Guenter > > Hi Guenter, > > Intermixing writel() with writel_relaxed() is unavoidable here. Because there cannot be a memory barrier between writing UNLOCK_SEQ0 and writing UNLOCK_SEQ1. This may be determined by hardware design. > If it is indeed impossible to configure the watchdog for 32-bit access mode, that needs to be explained in the code and backed up, for example with a reference to the documentation. Similar, it needs to be documented in the code why writel() does not work here and why mb() is needed. Thanks, Guenter > Best Regards, > Alice Guo > > > > + } > > > > > > ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); > > > if (ret) > > > -- > > > 2.17.1 > > >
diff --git a/drivers/watchdog/imx7ulp_wdt.c b/drivers/watchdog/imx7ulp_wdt.c index b8ac0cb04d2f..a0f6b8cea78f 100644 --- a/drivers/watchdog/imx7ulp_wdt.c +++ b/drivers/watchdog/imx7ulp_wdt.c @@ -180,11 +180,16 @@ static int imx7ulp_wdt_init(void __iomem *base, unsigned int timeout) local_irq_disable(); - mb(); - /* unlock the wdog for reconfiguration */ - writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); - writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); - mb(); + val = readl(base + WDOG_CS); + if (val & WDOG_CS_CMD32EN) { + writel(UNLOCK, base + WDOG_CNT); + } else { + mb(); + /* unlock the wdog for reconfiguration */ + writel_relaxed(UNLOCK_SEQ0, base + WDOG_CNT); + writel_relaxed(UNLOCK_SEQ1, base + WDOG_CNT); + mb(); + } ret = imx7ulp_wdt_wait(base, WDOG_CS_ULK); if (ret)