On 11/02/2017 07:32 PM, Joel Stanley wrote:
On Fri, Nov 3, 2017 at 1:54 AM, Guenter Roeck <linux@xxxxxxxxxxxx> 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
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