Re: patch "xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()" added to usb-linus

[Raul Rangel <rrangel@chromium.org>]

Mathias,
Are there any plans to backport this to the other kernels?

Looks like it landed upstream as f7fac17ca925faa03fc5eb854c081a24075f8bad

Thanks,
Raul
On Wed, May 22, 2019 at 02:27:29PM +0200, gregkh@linuxfoundation.org wrote:
> 
> This is a note to let you know that I've just added the patch titled
> 
>     xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()
> 
> to my usb git tree which can be found at
>     git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git
> in the usb-linus branch.
> 
> The patch will show up in the next release of the linux-next tree
> (usually sometime within the next 24 hours during the week.)
> 
> The patch will hopefully also be merged in Linus's tree for the
> next -rc kernel release.
> 
> If you have any questions about this process, please let me know.
> 
> 
> From f7fac17ca925faa03fc5eb854c081a24075f8bad Mon Sep 17 00:00:00 2001
> From: Andrey Smirnov <andrew.smirnov@gmail.com>
> Date: Wed, 22 May 2019 14:34:01 +0300
> Subject: xhci: Convert xhci_handshake() to use readl_poll_timeout_atomic()
> 
> 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(-)
> 
> diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
> index 048a675bbc52..20db378a6012 100644
> --- a/drivers/usb/host/xhci.c
> +++ b/drivers/usb/host/xhci.c
> @@ -9,6 +9,7 @@
>   */
>  
>  #include <linux/pci.h>
> +#include <linux/iopoll.h>
>  #include <linux/irq.h>
>  #include <linux/log2.h>
>  #include <linux/module.h>
> @@ -52,7 +53,6 @@ static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
>  	return false;
>  }
>  
> -/* 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
> @@ -69,18 +69,16 @@ static bool td_on_ring(struct xhci_td *td, struct xhci_ring *ring)
>  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;
>  }
>  
>  /*
> -- 
> 2.21.0
> 
>