> ... > > > > > > > > > + bool "Sunplus SP7021 PinMux and GPIO driver" > > > > > > > > > > > > > > Why bool and not tristate? > > > > > > > > > > > > Pinctrl driver is selected by many drivers in SP7021 platform. > > > > > > We never build it as a module, but build-in to kernel. > > > > > > So we use "bool". > > > > > > > > > > > > Should we set it to tristate? > > > > > > > > > > You still haven't answered "why", so I can't tell you. > > > > > > > > I am puzzled because I think I have answered "why". > > > > > > Nope. :-) > > > > > > > Because Pinctrl driver is necessary for all SP7021-based platforms. > > > > > > "Why?" Why is it necessary (to be built-in)? > > > > Pinctrl is necessary to be built-in because drivers of boot-device, > > like eMMC, SD card, NAND flash, and NOR flash drivers, need it. > > > > SP7021 supports booting from eMMC, SD card, NAND flash and NOR flash > > devices. Their drivers need Pinctrl driver probes in advance. > > On x86 platforms, for example, booting from eMMC and SD card does not require a pin > control driver to be built-in. Why is this requirement for SP platforms? > > -- > With Best Regards, > Andy Shevchenko Because all pins of boot-device multiplex with GPIO pins. SP7021 platforms support multi boot devices, including eMMC, SD card, SPI-NOR flash, SPI-NAND flash. Each boot device has control-bit(s) to enable it. For example #1, if control-bits of SPI-NOR flash is set 1, GPIO 83, 84, 86, 87 are connected to SPI-NOR flash. If control-bits of SPI-NOR flash is set 2, GPIO 76, 78, 79, 81 are connected to SPI-NOR flash. If control-bits of SPI-NOR flash is set 0, no pin is connected SPI-NOR flash. For example #2, if control-bits of eMMC device is set 1, GPIO 72, 73, 74, 75, 76, 77, 78, 79, 80, 81 are connected to eMMC device. If control-bits of eMMC device is set 0, no pin is connected eMMC device. For example #3, if control-bits of SDCard device is set 1, GPIO 65, 66, 67, 68, 69, 70 are connected to SD Card device. If control-bits of SDCard device is set 0, no pin is connected SDCard device. Note that all pins multiplex with GPIO pins. Normally, only a boot-device is enabled. All other GPIO pins are released for peripherals (controlled by fully-pinmux Or group pinmux) or IO processor Pinctrl driver is responsible for setup the pins. If Pinctrl fails to probe, boot-device also fails to probe. Best regards, Wells Lu
