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authorBen Dooks <ben-linux@fluff.org>2010-07-19 12:40:42 +0400
committerGreg Kroah-Hartman <gregkh@suse.de>2010-08-11 01:35:42 +0400
commite7a9ff54271bf0ddbf641e5a0bde3ebda35808be (patch)
tree92c9daeab81fdba8736c18ae1b2b27e652aa55b5 /drivers
parent679f9b7c7c7d3c746792138e9d7d76578ef52c41 (diff)
downloadlinux-e7a9ff54271bf0ddbf641e5a0bde3ebda35808be.tar.xz
USB: s3c-hsotg: Avoid overwriting contents of perodic in 'fifo'
In shared fifo mode (used on older SoCs) the periodic in fifo beahves much more like a packet buffer, discarding old data when writing new data. Avoid this by ensuring that we do not load new transactions in when there is data sitting already in the FIFO. Note, this may not be an observed bug, we are fixing the case that this may happen. Signed-off-by: Ben Dooks <ben-linux@fluff.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/usb/gadget/s3c-hsotg.c12
1 files changed, 11 insertions, 1 deletions
diff --git a/drivers/usb/gadget/s3c-hsotg.c b/drivers/usb/gadget/s3c-hsotg.c
index 4a251458c61d..354fd456f8cc 100644
--- a/drivers/usb/gadget/s3c-hsotg.c
+++ b/drivers/usb/gadget/s3c-hsotg.c
@@ -91,7 +91,9 @@ struct s3c_hsotg_req;
* For periodic IN endpoints, we have fifo_size and fifo_load to try
* and keep track of the amount of data in the periodic FIFO for each
* of these as we don't have a status register that tells us how much
- * is in each of them.
+ * is in each of them. (note, this may actually be useless information
+ * as in shared-fifo mode periodic in acts like a single-frame packet
+ * buffer than a fifo)
*/
struct s3c_hsotg_ep {
struct usb_ep ep;
@@ -474,6 +476,14 @@ static int s3c_hsotg_write_fifo(struct s3c_hsotg *hsotg,
size_left = S3C_DxEPTSIZ_XferSize_GET(epsize);
+ /* if shared fifo, we cannot write anything until the
+ * previous data has been completely sent.
+ */
+ if (hs_ep->fifo_load != 0) {
+ s3c_hsotg_en_gsint(hsotg, S3C_GINTSTS_PTxFEmp);
+ return -ENOSPC;
+ }
+
dev_dbg(hsotg->dev, "%s: left=%d, load=%d, fifo=%d, size %d\n",
__func__, size_left,
hs_ep->size_loaded, hs_ep->fifo_load, hs_ep->fifo_size);