upstream: [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>

diff --git a/drivers/media/usb/em28xx/em28xx-core.c b/drivers/media/usb/em28xx/em28xx-core.c
index cef3fd4..4a8763f 100644 (file)
--- 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 c2c68c8..7de35d3 100644 (file)
--- a/drivers/media/usb/em28xx/em28xx.h
+++ b/drivers/media/usb/em28xx/em28xx.h
@@ -183,6 +183,9 @@
 /* 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