usb: gadget: musb: fix short isoc packets with inventra dma

Handling short packets (length < max packet size) in the Inventra DMA
engine in the MUSB driver causes the MUSB DMA controller to hang. An
example of a problem that is caused by this problem is when streaming
video out of a UVC gadget, only the first video frame is transferred.

For short packets (mode-0 or mode-1 DMA), MUSB_TXCSR_TXPKTRDY must be
set manually by the driver. This was previously done in musb_g_tx
(musb_gadget.c), but incorrectly (all csr flags were cleared, and only
MUSB_TXCSR_MODE and MUSB_TXCSR_TXPKTRDY were set). Fixing that problem
allows some requests to be transferred correctly, but multiple requests
were often put together in one USB packet, and caused problems if the
packet size was not a multiple of 4. Instead, set MUSB_TXCSR_TXPKTRDY
in dma_controller_irq (musbhsdma.c), just like host mode transfers.

This topic was originally tackled by Nicolas Boichat [0] [1] and is
discussed further at [2] as part of his GSoC project [3].

[0] https://groups.google.com/forum/?hl=en#!topic/beagleboard-gsoc/k8Azwfp75CU
[1] https://gitorious.org/beagleboard-usbsniffer/beagleboard-usbsniffer-kernel/commit/b0be3b6cc195ba732189b04f1d43ec843c3e54c9?p=beagleboard-usbsniffer:beagleboard-usbsniffer-kernel.git;a=patch;h=b0be3b6cc195ba732189b04f1d43ec843c3e54c9
[2] http://beagleboard-usbsniffer.blogspot.com/2010/07/musb-isochronous-transfers-fixed.html
[3] http://elinux.org/BeagleBoard/GSoC/USBSniffer

Fixes: 550a7375fe72 ("USB: Add MUSB and TUSB support")
Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/musb/musb_gadget.c b/drivers/usb/musb/musb_gadget.c
index eae8b1b1b45b864a545827b9c5403b88b8779f78..ffe462a657b15d8b592ac7801dc6f4be4629c86f 100644 (file)
--- a/drivers/usb/musb/musb_gadget.c
+++ b/drivers/usb/musb/musb_gadget.c
@@ -452,13 +452,10 @@ void musb_g_tx(struct musb *musb, u8 epnum)
        }
 
        if (request) {
-               u8      is_dma = 0;
-               bool    short_packet = false;
 
                trace_musb_req_tx(req);
 
                if (dma && (csr & MUSB_TXCSR_DMAENAB)) {
-                       is_dma = 1;
                        csr |= MUSB_TXCSR_P_WZC_BITS;
                        csr &= ~(MUSB_TXCSR_DMAENAB | MUSB_TXCSR_P_UNDERRUN |
                                 MUSB_TXCSR_TXPKTRDY | MUSB_TXCSR_AUTOSET);
@@ -476,16 +473,8 @@ void musb_g_tx(struct musb *musb, u8 epnum)
                 */
                if ((request->zero && request->length)
                        && (request->length % musb_ep->packet_sz == 0)
-                       && (request->actual == request->length))
-                               short_packet = true;
+                       && (request->actual == request->length)) {
 
-               if ((musb_dma_inventra(musb) || musb_dma_ux500(musb)) &&
-                       (is_dma && (!dma->desired_mode ||
-                               (request->actual &
-                                       (musb_ep->packet_sz - 1)))))
-                               short_packet = true;
-
-               if (short_packet) {
                        /*
                         * On DMA completion, FIFO may not be
                         * available yet...

diff --git a/drivers/usb/musb/musbhsdma.c b/drivers/usb/musb/musbhsdma.c
index a688f7f87829f760c9fdee9008f6ca365e342dd3..5fc6825745f21bd6246d71b99fd98d7313396f01 100644 (file)
--- a/drivers/usb/musb/musbhsdma.c
+++ b/drivers/usb/musb/musbhsdma.c
@@ -346,12 +346,10 @@ static irqreturn_t dma_controller_irq(int irq, void *private_data)
                                channel->status = MUSB_DMA_STATUS_FREE;
 
                                /* completed */
-                               if ((devctl & MUSB_DEVCTL_HM)
-                                       && (musb_channel->transmit)
-                                       && ((channel->desired_mode == 0)
-                                           || (channel->actual_len &
-                                           (musb_channel->max_packet_sz - 1)))
-                                   ) {
+                               if (musb_channel->transmit &&
+                                       (!channel->desired_mode ||
+                                       (channel->actual_len %
+                                           musb_channel->max_packet_sz))) {
                                        u8  epnum  = musb_channel->epnum;
                                        int offset = musb->io.ep_offset(epnum,
                                                                    MUSB_TXCSR);
@@ -363,11 +361,14 @@ static irqreturn_t dma_controller_irq(int irq, void *private_data)
                                         */
                                        musb_ep_select(mbase, epnum);
                                        txcsr = musb_readw(mbase, offset);
-                                       txcsr &= ~(MUSB_TXCSR_DMAENAB
+                                       if (channel->desired_mode == 1) {
+                                               txcsr &= ~(MUSB_TXCSR_DMAENAB
                                                        | MUSB_TXCSR_AUTOSET);
-                                       musb_writew(mbase, offset, txcsr);
-                                       /* Send out the packet */
-                                       txcsr &= ~MUSB_TXCSR_DMAMODE;
+                                               musb_writew(mbase, offset, txcsr);
+                                               /* Send out the packet */
+                                               txcsr &= ~MUSB_TXCSR_DMAMODE;
+                                               txcsr |= MUSB_TXCSR_DMAENAB;
+                                       }
                                        txcsr |=  MUSB_TXCSR_TXPKTRDY;
                                        musb_writew(mbase, offset, txcsr);
                                }