[PATCH] usb: musb: dsps: handle the otg_state_a_wait_vrise_timeout case

Hi Felipe,
 
 On lun., oct. 05 2015, Felipe Balbi [off-list ref] wrote:

quoted

So after many tests on different devices, 200ms is enough for most of
them, but for one, 2000ms (2s) was needed!

I see several option:
- adding a sysfs entry to setup the time
- adding a debugs entry entry
- adding configuration option in menuconfig
- using 2000ms and hopping it was enough for everyone

My preference would go to the first option, what is your opinion?

I'm not sure if either of them is good. man 2s is just too large. If the
device isn't following the specification, I'm afraid that device needs
to be fixed.

I think the real issue here is the lack of a disconnect IRQ from AM335x
devices. But here's something I've been meaning to test but never had
time. If you look into AM335x address space, there's a bit in the
wrapper which tells it to use the standard MUSB registers for IRQ,
instead of the TI-specific thing. Can you see if we get a disconnect IRQ
with that ?

TRM is at [1], see page 2566. Basically, if you set bit 3 in register
offset 0x1014, then it should use Mentor IRQ registers. If that works,
quite a few problems will actually vanish :-p

So I tried it with the following patch:

-------------------------------------

diff --git a/drivers/usb/musb/musb_dsps.c b/drivers/usb/musb/musb_dsps.c
index c791ba5..c714500 100644
--- a/drivers/usb/musb/musb_dsps.c
+++ b/drivers/usb/musb/musb_dsps.c

@@ -470,6 +470,7 @@ static int dsps_musb_init(struct musb *musb)
 
        /* Reset the musb */
        dsps_writel(reg_base, wrp->control, (1 << wrp->reset));
+       dsps_writel(musb->ctrl_base, wrp->control, BIT(3));
 
        musb->isr = dsps_interrupt;
 

@@ -625,6 +626,7 @@ static int dsps_musb_reset(struct musb *musb)
        if (session_restart || !glue->sw_babble_enabled) {
                dev_info(musb->controller, "Restarting MUSB to recover from Babble\n");
                dsps_writel(musb->ctrl_base, wrp->control, (1 << wrp->reset));
+               dsps_writel(musb->ctrl_base, wrp->control, BIT(3));
                usleep_range(100, 200);
                usb_phy_shutdown(musb->xceiv);
                usleep_range(100, 200);
------------------------------------

I am not very familiar with that driver but my understanding was that
the Mentor IRQ registeres are managed by the musb_interrupt() function
which is called from the dsps_interrupt() interrupt handler.

Am I right?

if it is the case then it didn't fix the issue I had.

I activated the following debug line:

[musb_hdrc]musb_interrupt =_ "** IRQ %s usb%04x tx%04x rx%04x\012"
[musb_dsps]dsps_interrupt =p "usbintr (%x) epintr(%x)\012"

But I didn't get any interrupt while disconnecting the cable without any
device connected on it (whereas I got an interrupt when I connected it).

Note that I applied this patch instead of the "usb: musb: dsps: handle
the otg_state_a_wait_vrise_timeout case", is what you had in mind ?

Gregory

[1] http://www.ti.com/lit/ug/spruh73l/spruh73l.pdf

-- 
balbi

-- 
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com