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    Subject[PATCH 4.4 194/241] xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()
    Date
    From: Andrey Smirnov <andrew.smirnov@gmail.com>

    commit f7fac17ca925faa03fc5eb854c081a24075f8bad upstream.

    Xhci_handshake() implements the algorithm already captured by
    readl_poll_timeout_atomic(). Convert the former to use the latter to
    avoid repetition.

    Turned out this patch also fixes a bug on the AMD Stoneyridge platform
    where usleep(1) sometimes takes over 10ms.
    This means a 5 second timeout can easily take over 15 seconds which will
    trigger the watchdog and reboot the system.

    [Add info about patch fixing a bug to commit message -Mathias]
    Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
    Tested-by: Raul E Rangel <rrangel@chromium.org>
    Reviewed-by: Raul E Rangel <rrangel@chromium.org>
    Cc: <stable@vger.kernel.org>
    Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/usb/host/xhci.c | 22 ++++++++++------------
    1 file changed, 10 insertions(+), 12 deletions(-)

    --- a/drivers/usb/host/xhci.c
    +++ b/drivers/usb/host/xhci.c
    @@ -21,6 +21,7 @@
    */

    #include <linux/pci.h>
    +#include <linux/iopoll.h>
    #include <linux/irq.h>
    #include <linux/log2.h>
    #include <linux/module.h>
    @@ -46,7 +47,6 @@ static unsigned int quirks;
    module_param(quirks, uint, S_IRUGO);
    MODULE_PARM_DESC(quirks, "Bit flags for quirks to be enabled as default");

    -/* TODO: copied from ehci-hcd.c - can this be refactored? */
    /*
    * xhci_handshake - spin reading hc until handshake completes or fails
    * @ptr: address of hc register to be read
    @@ -63,18 +63,16 @@ MODULE_PARM_DESC(quirks, "Bit flags for
    int xhci_handshake(void __iomem *ptr, u32 mask, u32 done, int usec)
    {
    u32 result;
    + int ret;

    - do {
    - result = readl(ptr);
    - if (result == ~(u32)0) /* card removed */
    - return -ENODEV;
    - result &= mask;
    - if (result == done)
    - return 0;
    - udelay(1);
    - usec--;
    - } while (usec > 0);
    - return -ETIMEDOUT;
    + ret = readl_poll_timeout_atomic(ptr, result,
    + (result & mask) == done ||
    + result == U32_MAX,
    + 1, usec);
    + if (result == U32_MAX) /* card removed */
    + return -ENODEV;
    +
    + return ret;
    }

    /*

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