[coreboot] Patch set updated: 89461d8 port_enable and port_reset must change atomically.
Steven A. Falco (sfalco@coincident.com)
gerrit at coreboot.org
Sat Jul 16 03:52:56 CEST 2011
Steven A. Falco (sfalco at coincident.com) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/101
-gerrit
commit 89461d88a0e163ab5fee96908a4195035fe800f5
Author: Steven A. Falco <sfalco at coincident.com>
Date: Fri Jul 15 21:44:35 2011 -0400
port_enable and port_reset must change atomically.
I have observed two separate EHCI host bridges that do not tolerate
using C bit-fields to directly manipulate the portsc_t register. The
reason for this is that the EHCI spec says that port_enable must go
to 0 at the time that port_reset goes to 1. Naturally this cannot be
done using direct bit-field manipulation. Instead, we use a temporary
variable, change the bit-fields there, then atomically write the new
value back to the hardware.
Signed-off-by: Steven A. Falco <sfalco at coincident.com>
Change-Id: If138faee43e0293efa203b86f7893fdf1e811269
---
payloads/libpayload/drivers/usb/ehci_rh.c | 39 +++++++++++++++++++++++-----
1 files changed, 32 insertions(+), 7 deletions(-)
diff --git a/payloads/libpayload/drivers/usb/ehci_rh.c b/payloads/libpayload/drivers/usb/ehci_rh.c
index 5eaeeb6..5f0db94 100644
--- a/payloads/libpayload/drivers/usb/ehci_rh.c
+++ b/payloads/libpayload/drivers/usb/ehci_rh.c
@@ -54,14 +54,19 @@ static void
ehci_rh_hand_over_port (usbdev_t *dev, int port)
{
volatile portsc_t *p = &(RH_INST(dev)->ports[port]);
+ volatile portsc_t tmp;
printf("giving up port %x, it's USB1\n", port+1);
/* Lowspeed device. Hand over to companion */
- p->port_owner = 1;
+ tmp = *p;
+ tmp.port_owner = 1;
+ *p = tmp;
do {} while (!p->conn_status_change);
/* RW/C register, so clear it by writing 1 */
- p->conn_status_change = 1;
+ tmp = *p;
+ tmp.conn_status_change = 1;
+ *p = tmp;
return;
}
@@ -69,6 +74,7 @@ static void
ehci_rh_scanport (usbdev_t *dev, int port)
{
volatile portsc_t *p = &(RH_INST(dev)->ports[port]);
+ volatile portsc_t tmp;
if (RH_INST(dev)->devices[port]!=-1) {
printf("Unregister device at port %x\n", port+1);
usb_detach_device(dev->controller, RH_INST(dev)->devices[port]);
@@ -81,10 +87,22 @@ ehci_rh_scanport (usbdev_t *dev, int port)
ehci_rh_hand_over_port(dev, port);
return;
}
- p->port_enable = 0;
- p->port_reset = 1;
+
+ /* Deassert enable, assert reset. These must change
+ * atomically.
+ */
+ tmp = *p;
+ tmp.port_enable = 0;
+ tmp.port_reset = 1;
+ *p = tmp;
+
+ /* Wait a bit while reset is active. */
mdelay(50);
- p->port_reset = 0;
+
+ /* Deassert reset. */
+ tmp.port_reset = 0;
+ *p = tmp;
+
/* Wait for flag change to finish. The controller might take a while */
while (p->port_reset) ;
if (!p->port_enable) {
@@ -95,7 +113,9 @@ ehci_rh_scanport (usbdev_t *dev, int port)
RH_INST(dev)->devices[port] = usb_attach_device(dev->controller, dev->address, port, 2);
}
/* RW/C register, so clear it by writing 1 */
- p->conn_status_change = 1;
+ tmp = *p;
+ tmp.conn_status_change = 1;
+ *p = tmp;
}
static int
@@ -122,6 +142,8 @@ void
ehci_rh_init (usbdev_t *dev)
{
int i;
+ volatile portsc_t *p;
+ volatile portsc_t tmp;
dev->destroy = ehci_rh_destroy;
dev->poll = ehci_rh_poll;
@@ -135,8 +157,11 @@ ehci_rh_init (usbdev_t *dev)
RH_INST(dev)->devices = malloc(RH_INST(dev)->n_ports * sizeof(int));
for (i=0; i < RH_INST(dev)->n_ports; i++) {
+ p = &(RH_INST(dev)->ports[i]);
RH_INST(dev)->devices[i] = -1;
- RH_INST(dev)->ports[i].pp = 1;
+ tmp = *p;
+ tmp.pp = 1;
+ *p = tmp;
}
dev->address = 0;
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