[media] em28xx: properly implement AC97 wait code

Instead of assuming that msleep() is precise, use a jiffies
based code to wait for AC97 to be available.

Reviewed-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

2 files changed, 8 insertions, 2 deletions

diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
index b5f49703f7ce..b6dc3327c51c 100644
--- a/drivers/media/usb/em28xx/em28xx-core.c
+++ b/drivers/media/usb/em28xx/em28xx-core.c
@@ -23,6 +23,7 @@
  */
 
 #include <linux/init.h>
+#include <linux/jiffies.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/slab.h>
@@ -252,16 +253,18 @@ EXPORT_SYMBOL_GPL(em28xx_toggle_reg_bits);
  */
 static int em28xx_is_ac97_ready(struct em28xx *dev)
 {
-        int ret, i;
+        unsigned long timeout = jiffies + msecs_to_jiffies(EM28XX_AC97_XFER_TIMEOUT);
+        int ret;
 
         /* Wait up to 50 ms for AC97 command to complete */
-        for (i = 0; i < 10; i++, msleep(5)) {
+        while (time_is_after_jiffies(timeout)) {
                 ret = em28xx_read_reg(dev, EM28XX_R43_AC97BUSY);
                 if (ret < 0)
                         return ret;
 
                 if (!(ret & 0x01))
                         return 0;
+                msleep(5);
         }
 
         em28xx_warn("AC97 command still being executed: not handled properly!\n");
diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
index b792f2225abd..b0aa8497c1a9 100644
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -186,6 +186,9 @@
 /* time in msecs to wait for i2c writes to finish */
 #define EM2800_I2C_XFER_TIMEOUT         20
 
+/* time in msecs to wait for AC97 xfers to finish */
+#define EM28XX_AC97_XFER_TIMEOUT        100
+
 /* max. number of button state polling addresses */
 #define EM28XX_NUM_BUTTON_ADDRESSES_MAX         5