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Subject[PATCH 7/8] ehci-dbgp: split PID register updates for IN and OUT pipes
Date
This patch addresses two problems:

1) Bulk reads should always use the DATA0 for the pid, and the write
PID should toggle between DATA0 and DATA1. The fix is using
dbgp_pid_write_update() and dbgp_pid_read_update().

2) The delay loop for waiting for a transaction was not long enough to
always complete the initial handshake inside dbgp_wait_until_done().
After the initial handshake the maximum delay length is never reached.

The combined result of these two changes allows for the removal of the
forced resynchronization where a bulk write was issued with a dummy
data payload only to get the device to start accepting data writes
again.

CC: Greg Kroah-Hartman <gregkh@suse.de>
CC: Eric Biederman <ebiederm@xmission.com>
CC: Yinghai Lu <yhlu.kernel@gmail.com>
CC: linux-usb@vger.kernel.org
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
---
drivers/usb/early/ehci-dbgp.c | 68 +++++++++++++++++------------------------
1 files changed, 28 insertions(+), 40 deletions(-)
diff --git a/drivers/usb/early/ehci-dbgp.c b/drivers/usb/early/ehci-dbgp.c
index 2958a12..6e98a36 100644
--- a/drivers/usb/early/ehci-dbgp.c
+++ b/drivers/usb/early/ehci-dbgp.c
@@ -66,8 +66,6 @@ static struct ehci_dev ehci_dev;

#define USB_DEBUG_DEVNUM 127

-#define DBGP_DATA_TOGGLE 0x8800
-
#ifdef DBGP_DEBUG
#define dbgp_printk printk
static void dbgp_ehci_status(char *str)
@@ -88,11 +86,6 @@ static inline void dbgp_ehci_status(char *str) { }
static inline void dbgp_printk(const char *fmt, ...) { }
#endif

-static inline u32 dbgp_pid_update(u32 x, u32 tok)
-{
- return ((x ^ DBGP_DATA_TOGGLE) & 0xffff00) | (tok & 0xff);
-}
-
static inline u32 dbgp_len_update(u32 x, u32 len)
{
return (x & ~0x0f) | (len & 0x0f);
@@ -136,6 +129,19 @@ static inline u32 dbgp_len_update(u32 x, u32 len)

#define DBGP_MAX_PACKET 8
#define DBGP_TIMEOUT (250 * 1000)
+#define DBGP_LOOPS 1000
+
+static inline u32 dbgp_pid_write_update(u32 x, u32 tok)
+{
+ static int data0 = USB_PID_DATA1;
+ data0 ^= USB_PID_DATA_TOGGLE;
+ return (x & 0xffff0000) | (data0 << 8) | (tok & 0xff);
+}
+
+static inline u32 dbgp_pid_read_update(u32 x, u32 tok)
+{
+ return (x & 0xffff0000) | (USB_PID_DATA0 << 8) | (tok & 0xff);
+}

static int dbgp_wait_until_complete(void)
{
@@ -180,7 +186,7 @@ static int dbgp_wait_until_done(unsigned ctrl)
{
u32 pids, lpid;
int ret;
- int loop = 3;
+ int loop = DBGP_LOOPS;

retry:
writel(ctrl | DBGP_GO, &ehci_debug->control);
@@ -197,6 +203,8 @@ retry:
*/
if (ret == -DBGP_TIMEOUT && !dbgp_not_safe)
dbgp_not_safe = 1;
+ if (ret == -DBGP_ERR_BAD && --loop > 0)
+ goto retry;
return ret;
}

@@ -245,12 +253,20 @@ static inline void dbgp_get_data(void *buf, int size)
bytes[i] = (hi >> (8*(i - 4))) & 0xff;
}

-static int dbgp_out(u32 addr, const char *bytes, int size)
+static int dbgp_bulk_write(unsigned devnum, unsigned endpoint,
+ const char *bytes, int size)
{
+ int ret;
+ u32 addr;
u32 pids, ctrl;

+ if (size > DBGP_MAX_PACKET)
+ return -1;
+
+ addr = DBGP_EPADDR(devnum, endpoint);
+
pids = readl(&ehci_debug->pids);
- pids = dbgp_pid_update(pids, USB_PID_OUT);
+ pids = dbgp_pid_write_update(pids, USB_PID_OUT);

ctrl = readl(&ehci_debug->control);
ctrl = dbgp_len_update(ctrl, size);
@@ -260,34 +276,7 @@ static int dbgp_out(u32 addr, const char *bytes, int size)
dbgp_set_data(bytes, size);
writel(addr, &ehci_debug->address);
writel(pids, &ehci_debug->pids);
- return dbgp_wait_until_done(ctrl);
-}
-
-static int dbgp_bulk_write(unsigned devnum, unsigned endpoint,
- const char *bytes, int size)
-{
- int ret;
- int loops = 5;
- u32 addr;
- if (size > DBGP_MAX_PACKET)
- return -1;
-
- addr = DBGP_EPADDR(devnum, endpoint);
-try_again:
- if (loops--) {
- ret = dbgp_out(addr, bytes, size);
- if (ret == -DBGP_ERR_BAD) {
- int try_loops = 3;
- do {
- /* Emit a dummy packet to re-sync communication
- * with the debug device */
- if (dbgp_out(addr, "12345678", 8) >= 0) {
- udelay(2);
- goto try_again;
- }
- } while (try_loops--);
- }
- }
+ ret = dbgp_wait_until_done(ctrl);

return ret;
}
@@ -304,7 +293,7 @@ static int dbgp_bulk_read(unsigned devnum, unsigned endpoint, void *data,
addr = DBGP_EPADDR(devnum, endpoint);

pids = readl(&ehci_debug->pids);
- pids = dbgp_pid_update(pids, USB_PID_IN);
+ pids = dbgp_pid_read_update(pids, USB_PID_IN);

ctrl = readl(&ehci_debug->control);
ctrl = dbgp_len_update(ctrl, size);
@@ -362,7 +351,6 @@ static int dbgp_control_msg(unsigned devnum, int requesttype,
return dbgp_bulk_read(devnum, 0, data, size);
}

-
/* Find a PCI capability */
static u32 __init find_cap(u32 num, u32 slot, u32 func, int cap)
{
--
1.6.4.rc1


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