| Message ID | 1486803415-14680-1-git-send-email-w@1wt.eu (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi Willy, Am Samstag, 11. Februar 2017, 09:56:55 CET schrieb Willy Tarreau: > The MiQi board is sold with an enclosure in which a fan is connected > to the second LED output, and configured by default in "heartbeat" > mode so that it rotates slowly and increases when the CPU load > increases, ensuring appropriate cooling by default. This LED output > is called "Fan" in the original kernel and connected to GPIO18 > (gpiochip 0, pin 18). Here we called it "miqi:green:fan" to stay > consistent with the kernel's naming conventions. I tend to disagree with this approach. A fan is not a led and the devicetree is about describing the hardware, not how a specific kernel likes to use things :-) . The kernel already has a gpio-fan driver (drivers/hwmon) or you could resurrect the gpio-pwm patch [0] from Olliver Schinagl and use the pwm-fan on top of that for more intermediate steps. > It's worth noting that without this patch the fan doesn't work at > all, risking to make the board overheat. At least cpufreq is already hooked to the thermal controller on the rk3288, so even without additional cooling it should select lower cpu frequencies keeping the heat in line and prevent overheating the board. Both solutions shown above also hook into the thermal framework and act as cooling device according real temperature readings from the chip and not trying to determine some sort of cooling from load in a somewhat hacky way. Heiko [0] https://patchwork.kernel.org/patch/7492201/ > > Fixes: 162718c (v4.7) > Cc: Heiko Stuebner <heiko@sntech.de> > Signed-off-by: Willy Tarreau <w@1wt.eu> > --- > arch/arm/boot/dts/rk3288-miqi.dts | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/arm/boot/dts/rk3288-miqi.dts > b/arch/arm/boot/dts/rk3288-miqi.dts index 2f4c635..ef702db 100644 > --- a/arch/arm/boot/dts/rk3288-miqi.dts > +++ b/arch/arm/boot/dts/rk3288-miqi.dts > @@ -67,6 +67,12 @@ > leds { > compatible = "gpio-leds"; > > + fan { > + gpios = <&gpio0 18 GPIO_ACTIVE_HIGH>; > + label = "miqi:green:fan"; > + linux,default-trigger = "heartbeat"; > + }; > + > work { > gpios = <&gpio7 2 GPIO_ACTIVE_HIGH>; > label = "miqi:green:user";
Hi Heiko, On Sat, Feb 11, 2017 at 05:33:16PM +0100, Heiko Stuebner wrote: > Hi Willy, > > Am Samstag, 11. Februar 2017, 09:56:55 CET schrieb Willy Tarreau: > > The MiQi board is sold with an enclosure in which a fan is connected > > to the second LED output, and configured by default in "heartbeat" > > mode so that it rotates slowly and increases when the CPU load > > increases, ensuring appropriate cooling by default. This LED output > > is called "Fan" in the original kernel and connected to GPIO18 > > (gpiochip 0, pin 18). Here we called it "miqi:green:fan" to stay > > consistent with the kernel's naming conventions. > > I tend to disagree with this approach. A fan is not a led and the devicetree > is about describing the hardware, not how a specific kernel likes to use things > :-) . Sure but I was trying to stay as close as possible to the intended purpose of the connector on the board as it is sold :-) > The kernel already has a gpio-fan driver (drivers/hwmon) or you could > resurrect the gpio-pwm patch [0] from Olliver Schinagl and use the pwm-fan on > top of that for more intermediate steps. Ah it's great to know there has already been something like this because I thought about developing one for the same reason. > > It's worth noting that without this patch the fan doesn't work at > > all, risking to make the board overheat. > > At least cpufreq is already hooked to the thermal controller on the rk3288, so > even without additional cooling it should select lower cpu frequencies keeping > the heat in line and prevent overheating the board. Well that's one way to see it, as for me throttling the CPU is the last resort before seeing it die ; I find it sad to waste all the performance of a 3288 that way, otherwise it's easier to use something like a dirt a much slower and cheaper cortex A5. But I agree with the point regarding the gpio-pwm. I think that mqmaker initially designed the GPIO to be used as a led to benefit from the heartbeat trigger which more or less replaces what a more efficient thermal control could achieve. Thanks! Willy
Hi Willy, Am Samstag, 11. Februar 2017, 18:45:54 CET schrieb Willy Tarreau: > On Sat, Feb 11, 2017 at 05:33:16PM +0100, Heiko Stuebner wrote: > > Am Samstag, 11. Februar 2017, 09:56:55 CET schrieb Willy Tarreau: > > > The MiQi board is sold with an enclosure in which a fan is connected > > > to the second LED output, and configured by default in "heartbeat" > > > mode so that it rotates slowly and increases when the CPU load > > > increases, ensuring appropriate cooling by default. This LED output > > > is called "Fan" in the original kernel and connected to GPIO18 > > > (gpiochip 0, pin 18). Here we called it "miqi:green:fan" to stay > > > consistent with the kernel's naming conventions. > > > > I tend to disagree with this approach. A fan is not a led and the > > devicetree is about describing the hardware, not how a specific kernel > > likes to use things> > > :-) . > > Sure but I was trying to stay as close as possible to the intended > purpose of the connector on the board as it is sold :-) > > > The kernel already has a gpio-fan driver (drivers/hwmon) or you could > > resurrect the gpio-pwm patch [0] from Olliver Schinagl and use the pwm-fan > > on top of that for more intermediate steps. > > Ah it's great to know there has already been something like this because > I thought about developing one for the same reason. > > > > It's worth noting that without this patch the fan doesn't work at > > > all, risking to make the board overheat. > > > > At least cpufreq is already hooked to the thermal controller on the > > rk3288, so even without additional cooling it should select lower cpu > > frequencies keeping the heat in line and prevent overheating the board. > > Well that's one way to see it, as for me throttling the CPU is the last > resort before seeing it die ; That's what I was trying to say :-) ... it won't overheat because cpufreq will throttle it as a last resort. > I find it sad to waste all the performance > of a 3288 that way, otherwise it's easier to use something like a dirt > a much slower and cheaper cortex A5. But I agree with the point regarding > the gpio-pwm. Even with the gpio-fan you should see results if you simply add the fan as active trip point somewhere before the cpufreq trip points. So let the fan get activated at 50/60° or so. Heiko > I think that mqmaker initially designed the GPIO to be used > as a led to benefit from the heartbeat trigger which more or less replaces > what a more efficient thermal control could achieve.
On Sun, Feb 12, 2017 at 02:41:35AM +0100, Heiko Stuebner wrote: > > I find it sad to waste all the performance > > of a 3288 that way, otherwise it's easier to use something like a dirt > > a much slower and cheaper cortex A5. But I agree with the point regarding > > the gpio-pwm. > > Even with the gpio-fan you should see results if you simply add the fan as > active trip point somewhere before the cpufreq trip points. So let the fan get > activated at 50/60° or so. Better not do it as-is, the small fan is extremely noisy. That was the benefit of the heartbeat mode, it was a poor man's pwm. I'll see what I can do with the gpio-pwm. BTW, on all my MiQi, I have raised the critical points to 90 degrees, one of my workplace build farm made of 4 MiQi, I have connected a large slow fan which start to run above 85 degrees and it's enough to prevent the critical point from ever being reached. The dissipate heat is very low and the heatsink small so with minimal air flow, the temperature drops very quickly. Thanks, Willy
diff --git a/arch/arm/boot/dts/rk3288-miqi.dts b/arch/arm/boot/dts/rk3288-miqi.dts index 2f4c635..ef702db 100644 --- a/arch/arm/boot/dts/rk3288-miqi.dts +++ b/arch/arm/boot/dts/rk3288-miqi.dts @@ -67,6 +67,12 @@ leds { compatible = "gpio-leds"; + fan { + gpios = <&gpio0 18 GPIO_ACTIVE_HIGH>; + label = "miqi:green:fan"; + linux,default-trigger = "heartbeat"; + }; + work { gpios = <&gpio7 2 GPIO_ACTIVE_HIGH>; label = "miqi:green:user";
The MiQi board is sold with an enclosure in which a fan is connected to the second LED output, and configured by default in "heartbeat" mode so that it rotates slowly and increases when the CPU load increases, ensuring appropriate cooling by default. This LED output is called "Fan" in the original kernel and connected to GPIO18 (gpiochip 0, pin 18). Here we called it "miqi:green:fan" to stay consistent with the kernel's naming conventions. It's worth noting that without this patch the fan doesn't work at all, risking to make the board overheat. Fixes: 162718c (v4.7) Cc: Heiko Stuebner <heiko@sntech.de> Signed-off-by: Willy Tarreau <w@1wt.eu> --- arch/arm/boot/dts/rk3288-miqi.dts | 6 ++++++ 1 file changed, 6 insertions(+)