From a9c174302b1590ef3ead485d804a303c5f89174b Mon Sep 17 00:00:00 2001 From: Michael Grzeschik Date: Thu, 4 Apr 2013 13:13:46 +0300 Subject: [PATCH] usb: chipidea: udc: fix memory access of shared memory on armv5 machines The udc uses an shared dma memory space between hard and software. This memory layout is described in ci13xxx_qh and ci13xxx_td which are marked with the attribute ((packed)). The compiler currently does not know about the alignment of the memory layout, and will create strb and ldrb operations. The Datasheet of the synopsys core describes, that some operations on the mapped memory need to be atomic double word operations. I.e. the next pointer addressing in the qhead, as otherwise the hardware will read wrong data and totally stuck. This is also possible while working with the current active td queue, and preparing the td->ptr.next in software while the hardware is still working with the current active td which is supposed to be changed: writeb(0xde, &td->ptr.next + 0x0); /* strb */ writeb(0xad, &td->ptr.next + 0x1); /* strb */ <----- hardware reads value of td->ptr.next and get stuck! writeb(0xbe, &td->ptr.next + 0x2); /* strb */ writeb(0xef, &td->ptr.next + 0x3); /* strb */ This appeares on armv5 machines where the hardware does not support unaligned 32bit operations. This patch adds the attribute ((aligned(4))) to the structures to tell the compiler to use 32bit operations. It also adds an wmb() for the prepared TD data before it gets enqueued into the qhead. Cc: stable # v3.5 Signed-off-by: Michael Grzeschik Reviewed-by: Felipe Balbi Signed-off-by: Alexander Shishkin Signed-off-by: Greg Kroah-Hartman --- drivers/usb/chipidea/udc.c | 2 ++ drivers/usb/chipidea/udc.h | 4 ++-- 2 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c index e502e4807812..b4cac44ce26c 100644 --- a/drivers/usb/chipidea/udc.c +++ b/drivers/usb/chipidea/udc.c @@ -435,6 +435,8 @@ static int _hardware_enqueue(struct ci13xxx_ep *mEp, struct ci13xxx_req *mReq) mReq->ptr->page[i] = cpu_to_le32(page); } + wmb(); + if (!list_empty(&mEp->qh.queue)) { struct ci13xxx_req *mReqPrev; int n = hw_ep_bit(mEp->num, mEp->dir); diff --git a/drivers/usb/chipidea/udc.h b/drivers/usb/chipidea/udc.h index 4ff2384d7ca8..d12e8b59b110 100644 --- a/drivers/usb/chipidea/udc.h +++ b/drivers/usb/chipidea/udc.h @@ -40,7 +40,7 @@ struct ci13xxx_td { #define TD_CURR_OFFSET (0x0FFFUL << 0) #define TD_FRAME_NUM (0x07FFUL << 0) #define TD_RESERVED_MASK (0x0FFFUL << 0) -} __attribute__ ((packed)); +} __attribute__ ((packed, aligned(4))); /* DMA layout of queue heads */ struct ci13xxx_qh { @@ -57,7 +57,7 @@ struct ci13xxx_qh { /* 9 */ u32 RESERVED; struct usb_ctrlrequest setup; -} __attribute__ ((packed)); +} __attribute__ ((packed, aligned(4))); /** * struct ci13xxx_req - usb request representation -- 2.39.5