On Tue, Jul 13, 2021 at 12:46:00PM +0200, Sebastian Reichel wrote:

Hi,

On Tue, Jul 13, 2021 at 07:41:51AM +0200, Greg Kroah-Hartman wrote:

quoted

On Tue, Jul 13, 2021 at 01:20:16AM +0200, Sebastian Reichel wrote:

quoted

On Mon, Jul 12, 2021 at 07:46:05PM +0200, Greg Kroah-Hartman wrote:

quoted

On Mon, Jul 12, 2021 at 05:02:42PM +0200, Sebastian Reichel wrote:

quoted

General Electric Healthcare's PPD has a secondary processor from
NXP's Kinetis K20 series. That device has two SPI chip selects:

The main interface's behaviour depends on the loaded firmware
and is currently unused.

The secondary interface can be used to update the firmware using
EzPort protocol. This is implemented by this driver using the
kernel's firmware API. It's not done during probe time, since
the device has non-volatile memory and flashing lasts almost 3
minutes.

In thinking about this some more, why does it matter?  Spin up a
workqueue when probing and do the firmware loading then. That way you
do not end up creating yet another custom user/kernel api just to do
something as trivial as loading the firmware for a device.

And I think the firmware loader even handles async loading, or at least
it used to, maybe not anymore, it's a complex api, I recommend reading
the docs...

Flashing the firmware during boot instead of on-demand is not
a good idea for two reasons:

1. This will wear the flash memory of the microcontroller for no
   good reason.

Why would you boot with this hardware and not want the firmware
loaded?

As written in the commit message this code is updateing the firmware
in non-volatile memory, so the previously flashed FW will be used
until a new one is flashed.

The datasheet for the memory being programmed states, that it has a
guaranteed programming endurance of 10.000 times. So programming it
at every boot instead of manually when a new FW should be flashed
(i.e. once every few years) shortens the device life time considerably.

Ah, ok, that was not obvious at all.  This is much more like a "BIOS
update" in that it is infrequent.  You might want to document the heck
out of this so others are not confused like me.

thanks,

greg k-h