Hi,
On 27-03-15 02:21, Peter Chen wrote:
Hi Kishon,
I've been debugging why some devices do not work with the musb otg
controller found on Allwinner SoC-s, and the conclusion is not good, the
Android kernel does a poke to the phy before releasing the usb reset.
Now you did not want me to introduce any sunxi specific / private phy
functions in my initial patch-series for adding sunxi support, but in this case
I do
not really see an alternative, as this is a very platform specific hack to work
around an issue with the phy-s squelch detection which causes it to see a
squelch when reset is released switching it to high speed mode when a lo
speed device is connected, after which things fall apart.
The nofity_connect API at struct usb_phy may satisfy your requirement,
it will be called after bus rest has finished.
Thanks for the suggestion, but that is too late, I try to write a patch
set for this tonight (my sunxi musb work is a spare time project), as
I think that will make the discussion easier.
What I need is a way to disable squelch detection on the phy before clearing
the root port reset bit in the musb controller, currently we have this:
drivers/usb/musb/musb_virthub.c: void musb_port_reset()
if (do_reset) {
...
} else {
dev_dbg(musb->controller, "root port reset stopped\n");
musb_writeb(mbase, MUSB_POWER, power & ~MUSB_POWER_RESET);
...
}
In order to work around the phy bug I need to do this (I got this from
the Allwinner android kernel sources and it seems the only way):
if (do_reset) {
...
} else {
dev_dbg(musb->controller, "root port reset stopped\n");
musb_platform_pre_reset_end();
musb_writeb(mbase, MUSB_POWER, power & ~MUSB_POWER_RESET);
musb_platform_post_reset_end();
...
}
Notice the 2 new musb_platform_... calls, these are to be empty stubs for
all platforms except sunxi, where they need to call into the phy driver.
All in all I really believe this is so specific that a platform specific
phy callback is best, so that is what I'll do for the first version of
my patchset for this,
Regards,
Hans
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
