usb: musb: Perform only write access on MUSB_INTRRXE
This is part of the workaround for AM35x advisory Advisory 1.1.20.
The advisory says that the IPSS bridge can't handle 8 & 16 bit read
access. An 16bit read access to MUSB_INTRRXE results in an 32bit read
access which also reads INTRUSB and therefore may lose interrupts.
This patch uses a shadow register of MUSB_INTRRXE so we only perform
write access to it.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index b430f15..bb684f0 100644
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -1108,7 +1108,6 @@
musb_writew(regs, MUSB_TXCSR, csr);
} else {
- u16 int_rxe = musb_readw(mbase, MUSB_INTRRXE);
if (hw_ep->is_shared_fifo)
musb_ep->is_in = 0;
@@ -1120,8 +1119,8 @@
goto fail;
}
- int_rxe |= (1 << epnum);
- musb_writew(mbase, MUSB_INTRRXE, int_rxe);
+ musb->intrrxe |= (1 << epnum);
+ musb_writew(mbase, MUSB_INTRRXE, musb->intrrxe);
/* REVISIT if can_bulk_combine() use by updating "tmp"
* likewise high bandwidth periodic rx
@@ -1214,9 +1213,8 @@
musb_writew(musb->mregs, MUSB_INTRTXE, int_txe);
musb_writew(epio, MUSB_TXMAXP, 0);
} else {
- u16 int_rxe = musb_readw(musb->mregs, MUSB_INTRRXE);
- int_rxe &= ~(1 << epnum);
- musb_writew(musb->mregs, MUSB_INTRRXE, int_rxe);
+ musb->intrrxe &= ~(1 << epnum);
+ musb_writew(musb->mregs, MUSB_INTRRXE, musb->intrrxe);
musb_writew(epio, MUSB_RXMAXP, 0);
}