Hi Thierry, On Thu, Mar 15, 2018 at 12:07:44PM +0100, Thierry Escande wrote: > > > BT_DISABLE_N is the name of this pin in the datasheet of the QCA chip, > > > not on the board, so this name is the same regardless of what you name > > > the line or gpio your board connect it to. > > > > and QCA chip v1 and QCA chip v2 will use the same driver and > > same firmware loading mechanism. So why do we have to add a new > > GPIO naming if they decide to change the name in the data sheet. > > With Bluetooth it is pretty much all the same. Every UART chip > > has a shutdown/reset GPIO to enable/disable the chip behind the > > UART. > > > > > > A new board should not require driver changes, you just ship a new DT > > > > for that board and an existing driver hopefully just does the job. No > > > > matter how someone named a GPIO in a piece of paper. > > > > > > > > > > I totally agree with the fact that the board should not affect the > > > naming of the gpio in the driver. But I do enjoy when we refer to pins > > > by their real name - instead of having to guess which pin in the _chip_ > > > specification the driver actually refer to. > > > > > > > > > That said, what name would you prefer for this? > > > > > > Afaict this is not "wakeup" and there are a few extra steps between the > > > disabled state and "bluetooth is enabled", so "enable" feels slightly > > > wrong. And it probably should be "bluetooth" and not just "device" as > > > this refers to a pin on a WiFi/BT combo chip. > > > > The Broadcom side called it shutdown GPIO, it is essentially the > > shutdown/reset GPIO or power on/off GPIO. Personally I do not > > care what it is named, but it will be all the same for all > > Bluetooth chips. Take a poll from Broadcom, Intel, Realtek and > > Qualcomm and you can pick a reasonable common name. > > The Nokia driver has "bluetooth-wakeup" gpio. The Broadcom one has > "device-wakeup" and "shutdown". The "shutdown" gpio is set to its active > state to power on the chip which sounds reversed logic. Same for the > "bt-disable-n" gpio in the Qualcomm driver, configured as ACTIVE_HIGH, and > which is set to 1 to enable it... > > So for consistency, naming it as "shutdown" to stick to the bcm driver but > it should be configured as ACTIVE_LOW in the dts so we actually do a > gpiod_set_value(0) to un-shutdown it. Does that sound ok? FWIW you picked the wrong gpio from the nokia bluetooth binding. The gpio for shutdown would be "reset". The "bluetooth-wakeup" is required for normal operation to exit idle mode. The "reset" name used by the nokia binding is quite common for DT: Documentation/devicetree/bindings $ git grep reset-gpios | wc -l 212 I guess it only makes sense when the device is actually being reset, though (i.e. for Nokia the settings are back to defaults and you need to re-upload the FW). -- Sebastian > Regards, > Thierry > > > For the wakeup GPIOs, these are different and depend on if there > > is some low-power mode provided. You would need to check the > > data sheet to see if they provide more advanced low-power state > > handling. > > > > Regards > > > > Marcel > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html
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