| Message ID | 20171102035349.1902-3-joel@jms.id.au |
|---|---|
| State | New |
| Headers | show |
| Series | hwmon: Add reset support to aspeed-pwm-tach | expand |
On Thu, Nov 02, 2017 at 02:53:48PM +1100, Joel Stanley wrote: > The ASPEED SoC must deassert a reset in order to use the PWM/tach > peripheral. > Again, you claim that the current driver would not work at all, which is simply not correct. It doesn't work if the chip wasn't taken out of reset by other means. This doesn't take into account situations and hardware where the chip is taken out of reset automatically at boot, or by the ROM monitor/BIOS. It assumes that the reset pin can _always_ be controlled by software. Similar, it forces the chip into reset when the driver is removed, which is even worse. Unload the driver, and no more fan control ? Really ? Then why is there an autonomous chip for fan control to start with ? This is questionable even if the reset pin is optional. You'll have to make reset handling optional for me to accept it. I am quite sure that I said that before. Guenter > Signed-off-by: Joel Stanley <joel@jms.id.au> > --- > v2: > - Correct horrible mistakes > - Boot tested and hwmon sysfs files checked > --- > drivers/hwmon/aspeed-pwm-tacho.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c > index 63a95e23ca81..77bb7a4bbed4 100644 > --- a/drivers/hwmon/aspeed-pwm-tacho.c > +++ b/drivers/hwmon/aspeed-pwm-tacho.c > @@ -19,6 +19,7 @@ > #include <linux/of_platform.h> > #include <linux/platform_device.h> > #include <linux/regmap.h> > +#include <linux/reset.h> > #include <linux/sysfs.h> > #include <linux/thermal.h> > > @@ -181,6 +182,7 @@ struct aspeed_cooling_device { > > struct aspeed_pwm_tacho_data { > struct regmap *regmap; > + struct reset_control *rst; > unsigned long clk_freq; > bool pwm_present[8]; > bool fan_tach_present[16]; > @@ -931,6 +933,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) > &aspeed_pwm_tacho_regmap_config); > if (IS_ERR(priv->regmap)) > return PTR_ERR(priv->regmap); > + > + priv->rst = devm_reset_control_get_exclusive(dev, NULL); > + if (IS_ERR(priv->rst)) { > + dev_err(dev, > + "missing or invalid reset controller device tree entry"); > + return PTR_ERR(priv->rst); > + } > + reset_control_deassert(priv->rst); > + > regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE, 0); > regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE_EXT, 0); > > @@ -960,6 +971,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) > return PTR_ERR_OR_ZERO(hwmon); > } > > +static int aspeed_pwm_tacho_remove(struct platform_device *pdev) > +{ > + struct aspeed_pwm_tacho_data *priv = platform_get_drvdata(pdev); > + > + reset_control_assert(priv->rst); > + > + return 0; > +} > + > static const struct of_device_id of_pwm_tacho_match_table[] = { > { .compatible = "aspeed,ast2400-pwm-tacho", }, > { .compatible = "aspeed,ast2500-pwm-tacho", }, > @@ -969,6 +989,7 @@ MODULE_DEVICE_TABLE(of, of_pwm_tacho_match_table); > > static struct platform_driver aspeed_pwm_tacho_driver = { > .probe = aspeed_pwm_tacho_probe, > + .remove = aspeed_pwm_tacho_remove, > .driver = { > .name = "aspeed_pwm_tacho", > .of_match_table = of_pwm_tacho_match_table, > -- > 2.14.1 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, Nov 3, 2017 at 1:54 AM, Guenter Roeck <linux@roeck-us.net> wrote: > On Thu, Nov 02, 2017 at 02:53:48PM +1100, Joel Stanley wrote: >> The ASPEED SoC must deassert a reset in order to use the PWM/tach >> peripheral. >> > Again, you claim that the current driver would not work at all, which > is simply not correct. It doesn't work if the chip wasn't taken out > of reset by other means. This doesn't take into account situations and > hardware where the chip is taken out of reset automatically at boot, h > or by the ROM monitor/BIOS. It assumes that the reset pin can _always_ > be controlled by software. The reset is internal to the SoC. There is no pin to speak of, just a wire inside the SoC, so it can always be controlled by software. There's SoC does not release any resets automatically; the default value on boot is for the reset to be asserted and this is not configurable. > Similar, it forces the chip into reset when the driver is removed, > which is even worse. Unload the driver, and no more fan control ? > Really ? Then why is there an autonomous chip for fan control > to start with ? This is questionable even if the reset pin is > optional. Similarly, the PWM/Tach unit is inside the SoC; it's not an external device. It would be strange to remove the driver and expect the system to keep operating normally. > You'll have to make reset handling optional for me to accept it. > I am quite sure that I said that before. Please reconsider in light of the details above. It does not make any sense to build a system without this reset. Cheers, Joel > > Guenter > >> Signed-off-by: Joel Stanley <joel@jms.id.au> >> --- >> v2: >> - Correct horrible mistakes >> - Boot tested and hwmon sysfs files checked >> --- >> drivers/hwmon/aspeed-pwm-tacho.c | 21 +++++++++++++++++++++ >> 1 file changed, 21 insertions(+) >> >> diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c >> index 63a95e23ca81..77bb7a4bbed4 100644 >> --- a/drivers/hwmon/aspeed-pwm-tacho.c >> +++ b/drivers/hwmon/aspeed-pwm-tacho.c >> @@ -19,6 +19,7 @@ >> #include <linux/of_platform.h> >> #include <linux/platform_device.h> >> #include <linux/regmap.h> >> +#include <linux/reset.h> >> #include <linux/sysfs.h> >> #include <linux/thermal.h> >> >> @@ -181,6 +182,7 @@ struct aspeed_cooling_device { >> >> struct aspeed_pwm_tacho_data { >> struct regmap *regmap; >> + struct reset_control *rst; >> unsigned long clk_freq; >> bool pwm_present[8]; >> bool fan_tach_present[16]; >> @@ -931,6 +933,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) >> &aspeed_pwm_tacho_regmap_config); >> if (IS_ERR(priv->regmap)) >> return PTR_ERR(priv->regmap); >> + >> + priv->rst = devm_reset_control_get_exclusive(dev, NULL); >> + if (IS_ERR(priv->rst)) { >> + dev_err(dev, >> + "missing or invalid reset controller device tree entry"); >> + return PTR_ERR(priv->rst); >> + } >> + reset_control_deassert(priv->rst); >> + >> regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE, 0); >> regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE_EXT, 0); >> >> @@ -960,6 +971,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) >> return PTR_ERR_OR_ZERO(hwmon); >> } >> >> +static int aspeed_pwm_tacho_remove(struct platform_device *pdev) >> +{ >> + struct aspeed_pwm_tacho_data *priv = platform_get_drvdata(pdev); >> + >> + reset_control_assert(priv->rst); >> + >> + return 0; >> +} >> + >> static const struct of_device_id of_pwm_tacho_match_table[] = { >> { .compatible = "aspeed,ast2400-pwm-tacho", }, >> { .compatible = "aspeed,ast2500-pwm-tacho", }, >> @@ -969,6 +989,7 @@ MODULE_DEVICE_TABLE(of, of_pwm_tacho_match_table); >> >> static struct platform_driver aspeed_pwm_tacho_driver = { >> .probe = aspeed_pwm_tacho_probe, >> + .remove = aspeed_pwm_tacho_remove, >> .driver = { >> .name = "aspeed_pwm_tacho", >> .of_match_table = of_pwm_tacho_match_table, >> -- >> 2.14.1 >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-hwmon" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 11/02/2017 07:32 PM, Joel Stanley wrote: > On Fri, Nov 3, 2017 at 1:54 AM, Guenter Roeck <linux@roeck-us.net> wrote: >> On Thu, Nov 02, 2017 at 02:53:48PM +1100, Joel Stanley wrote: >>> The ASPEED SoC must deassert a reset in order to use the PWM/tach >>> peripheral. >>> >> Again, you claim that the current driver would not work at all, which >> is simply not correct. It doesn't work if the chip wasn't taken out >> of reset by other means. This doesn't take into account situations and >> hardware where the chip is taken out of reset automatically at boot, h >> or by the ROM monitor/BIOS. It assumes that the reset pin can _always_ >> be controlled by software. > > The reset is internal to the SoC. There is no pin to speak of, just a > wire inside the SoC, so it can always be controlled by software. > > There's SoC does not release any resets automatically; the default > value on boot is for the reset to be asserted and this is not > configurable. > >> Similar, it forces the chip into reset when the driver is removed, >> which is even worse. Unload the driver, and no more fan control ? >> Really ? Then why is there an autonomous chip for fan control >> to start with ? This is questionable even if the reset pin is >> optional. > > Similarly, the PWM/Tach unit is inside the SoC; it's not an external device. > > It would be strange to remove the driver and expect the system to keep > operating normally. > >> You'll have to make reset handling optional for me to accept it. >> I am quite sure that I said that before. > > Please reconsider in light of the details above. It does not make any > sense to build a system without this reset. > So you are saying that this driver never worked ? Hard to believe. I'll need input from other users. Guenter -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Nov 02, 2017 at 02:53:48PM +1100, Joel wrote: > The ASPEED SoC must deassert a reset in order to use the PWM/tach > peripheral. > > Signed-off-by: Joel Stanley <joel@jms.id.au> I have not heard from anyone objecting to this change, so I am going to accept it. See below for a list of changes required to get there. > --- > v2: > - Correct horrible mistakes > - Boot tested and hwmon sysfs files checked > --- > drivers/hwmon/aspeed-pwm-tacho.c | 21 +++++++++++++++++++++ > 1 file changed, 21 insertions(+) > > diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c > index 63a95e23ca81..77bb7a4bbed4 100644 > --- a/drivers/hwmon/aspeed-pwm-tacho.c > +++ b/drivers/hwmon/aspeed-pwm-tacho.c > @@ -19,6 +19,7 @@ > #include <linux/of_platform.h> > #include <linux/platform_device.h> > #include <linux/regmap.h> > +#include <linux/reset.h> > #include <linux/sysfs.h> > #include <linux/thermal.h> > > @@ -181,6 +182,7 @@ struct aspeed_cooling_device { > > struct aspeed_pwm_tacho_data { > struct regmap *regmap; > + struct reset_control *rst; > unsigned long clk_freq; > bool pwm_present[8]; > bool fan_tach_present[16]; > @@ -931,6 +933,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) > &aspeed_pwm_tacho_regmap_config); > if (IS_ERR(priv->regmap)) > return PTR_ERR(priv->regmap); > + > + priv->rst = devm_reset_control_get_exclusive(dev, NULL); > + if (IS_ERR(priv->rst)) { > + dev_err(dev, > + "missing or invalid reset controller device tree entry"); > + return PTR_ERR(priv->rst); > + } > + reset_control_deassert(priv->rst); > + > regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE, 0); > regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE_EXT, 0); > > @@ -960,6 +971,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) > return PTR_ERR_OR_ZERO(hwmon); > } > > +static int aspeed_pwm_tacho_remove(struct platform_device *pdev) > +{ > + struct aspeed_pwm_tacho_data *priv = platform_get_drvdata(pdev); > + > + reset_control_assert(priv->rst); This asserts reset before the hwmon device is removed. Please use devm_add_action_or_reset() after reset_control_deassert() to avoid this problem. > + > + return 0; > +} > + > static const struct of_device_id of_pwm_tacho_match_table[] = { > { .compatible = "aspeed,ast2400-pwm-tacho", }, > { .compatible = "aspeed,ast2500-pwm-tacho", }, > @@ -969,6 +989,7 @@ MODULE_DEVICE_TABLE(of, of_pwm_tacho_match_table); > > static struct platform_driver aspeed_pwm_tacho_driver = { > .probe = aspeed_pwm_tacho_probe, > + .remove = aspeed_pwm_tacho_remove, ... and by doing that you won't need the remove function, and you don't have to fix the checkpatch error here. > .driver = { > .name = "aspeed_pwm_tacho", > .of_match_table = of_pwm_tacho_match_table, -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/hwmon/aspeed-pwm-tacho.c b/drivers/hwmon/aspeed-pwm-tacho.c index 63a95e23ca81..77bb7a4bbed4 100644 --- a/drivers/hwmon/aspeed-pwm-tacho.c +++ b/drivers/hwmon/aspeed-pwm-tacho.c @@ -19,6 +19,7 @@ #include <linux/of_platform.h> #include <linux/platform_device.h> #include <linux/regmap.h> +#include <linux/reset.h> #include <linux/sysfs.h> #include <linux/thermal.h> @@ -181,6 +182,7 @@ struct aspeed_cooling_device { struct aspeed_pwm_tacho_data { struct regmap *regmap; + struct reset_control *rst; unsigned long clk_freq; bool pwm_present[8]; bool fan_tach_present[16]; @@ -931,6 +933,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) &aspeed_pwm_tacho_regmap_config); if (IS_ERR(priv->regmap)) return PTR_ERR(priv->regmap); + + priv->rst = devm_reset_control_get_exclusive(dev, NULL); + if (IS_ERR(priv->rst)) { + dev_err(dev, + "missing or invalid reset controller device tree entry"); + return PTR_ERR(priv->rst); + } + reset_control_deassert(priv->rst); + regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE, 0); regmap_write(priv->regmap, ASPEED_PTCR_TACH_SOURCE_EXT, 0); @@ -960,6 +971,15 @@ static int aspeed_pwm_tacho_probe(struct platform_device *pdev) return PTR_ERR_OR_ZERO(hwmon); } +static int aspeed_pwm_tacho_remove(struct platform_device *pdev) +{ + struct aspeed_pwm_tacho_data *priv = platform_get_drvdata(pdev); + + reset_control_assert(priv->rst); + + return 0; +} + static const struct of_device_id of_pwm_tacho_match_table[] = { { .compatible = "aspeed,ast2400-pwm-tacho", }, { .compatible = "aspeed,ast2500-pwm-tacho", }, @@ -969,6 +989,7 @@ MODULE_DEVICE_TABLE(of, of_pwm_tacho_match_table); static struct platform_driver aspeed_pwm_tacho_driver = { .probe = aspeed_pwm_tacho_probe, + .remove = aspeed_pwm_tacho_remove, .driver = { .name = "aspeed_pwm_tacho", .of_match_table = of_pwm_tacho_match_table,
The ASPEED SoC must deassert a reset in order to use the PWM/tach peripheral. Signed-off-by: Joel Stanley <joel@jms.id.au> --- v2: - Correct horrible mistakes - Boot tested and hwmon sysfs files checked --- drivers/hwmon/aspeed-pwm-tacho.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) -- 2.14.1 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html