[PATCH] xhci: Convert xhci_handshake() to use readl_poll_timeout()

[PATCH] xhci: Convert xhci_handshake() to use readl_poll_timeout()

[Andrey Smirnov]

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

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Mathias Nyman <mathias.nyman@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Cc: linux-kernel@vger.kernel.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 005e65922608..1b5306001340 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(ptr, result,
+				 (result & mask) == done ||
+				 result == U32_MAX,
+				 1, usec);
+	if (result == U32_MAX)		/* card removed */
+		return -ENODEV;
+
+	return ret;
 }
 
 /*
-- 
2.20.1

Re: [PATCH] xhci: Convert xhci_handshake() to use readl_poll_timeout()

[Mathias Nyman]

On 07.02.2019 02:03, Andrey Smirnov wrote:
> Xhci_handshake() implements the algorithm already captured by
> readl_poll_timeout(). Convert the former to use the latter to avoid
> repetition.

readl_poll_timeout() doesn't really work here as it might sleep.

iopoll.h:

/**
  * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
  *
...                                                                                                              
  * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
  * case, the last read value at @addr is stored in @val. Must not
  * be called from atomic context if sleep_us or timeout_us are used.
  
-Mathias

Re: [PATCH] xhci: Convert xhci_handshake() to use readl_poll_timeout()

[Felipe Balbi]

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Hi,

Mathias Nyman <mathias.nyman@linux.intel.com> writes:
> On 07.02.2019 02:03, Andrey Smirnov wrote:
>> Xhci_handshake() implements the algorithm already captured by
>> readl_poll_timeout(). Convert the former to use the latter to avoid
>> repetition.
>
> readl_poll_timeout() doesn't really work here as it might sleep.
>
> iopoll.h:
>
> /**
>   * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
>   *
> ...                                                                                                              
>   * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
>   * case, the last read value at @addr is stored in @val. Must not
>   * be called from atomic context if sleep_us or timeout_us are used.

readl_poll_timeout_atomic()?

-- 
balbi

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Re: [PATCH] xhci: Convert xhci_handshake() to use readl_poll_timeout()

[Andrey Smirnov]

On Thu, Feb 7, 2019 at 12:27 AM Mathias Nyman
<mathias.nyman@linux.intel.com> wrote:
>
> On 07.02.2019 02:03, Andrey Smirnov wrote:
> > Xhci_handshake() implements the algorithm already captured by
> > readl_poll_timeout(). Convert the former to use the latter to avoid
> > repetition.
>
> readl_poll_timeout() doesn't really work here as it might sleep.
>
> iopoll.h:
>
> /**
>   * readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs
>   *
> ...
>   * Returns 0 on success and -ETIMEDOUT upon a timeout. In either
>   * case, the last read value at @addr is stored in @val. Must not
>   * be called from atomic context if sleep_us or timeout_us are used.
>
> -Mathias

Shoot, missed this part. Will change to  readl_poll_timeout_atomic() in v2.

Thanks,
Andrey Smirnov