Hi Dmitry,
I guess that casting -1 to a u8 didn't have the effect that I thought it
would.
This looks correct, and we probably haven't run into this issue because
all the xHCI host controllers we've run into have well-formed port speed
arrays. I'll queue this.
On Wed, Feb 23, 2011 at 12:54:37AM -0800, Dmitry Torokhov wrote:
> From 76f7253356a10f698fbd9a3dba3ee633902526ae Mon Sep 17 00:00:00 2001
> From: Dmitry Torokhov <dtor@xxxxxxxxxx>
> Date: Wed, 23 Feb 2011 00:23:21 -0800
> Subject: [PATCH] USB: xhci - fix comparison when checking for duplicate ports
Can you please not send the above bit in future mails? It causes some
pain for maintainers (particularly since git-am accepts it fine, but git
rebase has some serious issues if you leave this bit in the commit
message).
Sarah Sharp
>
> Compiling with more strict compiler flags than default ones yeilds the
> following warning:
>
> cc1: warnings being treated as errors
> xhci-mem.c: In function 'xhci_setup_port_arrays':
> xhci-mem.c:1769: warning: comparison is always false due to limited
> range of data types
>
> which happens because port_array[] is u8 so after integer promotion
> the value is between 0 - 255 (no sign extension happens) but we
> compare it with -1.
>
> Signed-off-by: Dmitry Torokhov <dtor@xxxxxxxxxx>
> ---
>
> As far as I can see this is a real issue, still compiled only at this
> time.
>
> Thanks,
> Dmitry
>
> drivers/usb/host/xhci-mem.c | 9 +++++----
> drivers/usb/host/xhci.h | 1 +
> 2 files changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/usb/host/xhci-mem.c b/drivers/usb/host/xhci-mem.c
> index a953439..ef1edec 100644
> --- a/drivers/usb/host/xhci-mem.c
> +++ b/drivers/usb/host/xhci-mem.c
> @@ -1672,12 +1672,12 @@ static void xhci_add_in_port(struct xhci_hcd *xhci, unsigned int num_ports,
> * found a similar duplicate.
> */
> if (xhci->port_array[i] != major_revision &&
> - xhci->port_array[i] != (u8) -1) {
> + xhci->port_array[i] != XHCI_PORT_IGNORE) {
> if (xhci->port_array[i] == 0x03)
> xhci->num_usb3_ports--;
> else
> xhci->num_usb2_ports--;
> - xhci->port_array[i] = (u8) -1;
> + xhci->port_array[i] = XHCI_PORT_IGNORE;
> }
> /* FIXME: Should we disable the port? */
> continue;
> @@ -1761,9 +1761,10 @@ static int xhci_setup_port_arrays(struct xhci_hcd *xhci, gfp_t flags)
> port_index = 0;
> for (i = 0; i < num_ports; i++) {
> if (xhci->port_array[i] == 0x03 ||
> - xhci->port_array[i] == 0 ||
> - xhci->port_array[i] == -1)
> + xhci->port_array[i] == 0 ||
> + xhci->port_array[i] == XHCI_PORT_IGNORE) {
> continue;
> + }
>
> xhci->usb2_ports[port_index] =
> &xhci->op_regs->port_status_base +
> diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
> index 7f127df..b560cbc 100644
> --- a/drivers/usb/host/xhci.h
> +++ b/drivers/usb/host/xhci.h
> @@ -1255,6 +1255,7 @@ struct xhci_hcd {
> suspended */
> unsigned long resume_done[MAX_HC_PORTS];
> /* Is each xHCI roothub port a USB 3.0, USB 2.0, or USB 1.1 port? */
> +#define XHCI_PORT_IGNORE 0xff
> u8 *port_array;
> /* Array of pointers to USB 3.0 PORTSC registers */
> u32 __iomem **usb3_ports;
> --
> 1.7.3.2
>
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