sound: oxygen: work around MCE when changing volume

When the volume is changed continuously (e.g., when the user drags a
volume slider with the mouse), the driver does lots of I2C writes.
Apparently, the sound chip can get confused when we poll the I2C status
register too much, and fails to complete a read from it.  On the PCI-E
models, the PCI-E/PCI bridge gets upset by this and generates a machine
check exception.

To avoid this, this patch replaces the polling with an unconditional
wait that is guaranteed to be long enough.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Tested-by: Johann Messner <johann.messner at jku.at>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/pci/oxygen/oxygen_io.c b/sound/pci/oxygen/oxygen_io.c
index c1eb923..09b2b2a 100644 (file)
--- a/sound/pci/oxygen/oxygen_io.c
+++ b/sound/pci/oxygen/oxygen_io.c
@@ -215,17 +215,8 @@ EXPORT_SYMBOL(oxygen_write_spi);
 
 void oxygen_write_i2c(struct oxygen *chip, u8 device, u8 map, u8 data)
 {
-       unsigned long timeout;
-
        /* should not need more than about 300 us */
-       timeout = jiffies + msecs_to_jiffies(1);
-       do {
-               if (!(oxygen_read16(chip, OXYGEN_2WIRE_BUS_STATUS)
-                     & OXYGEN_2WIRE_BUSY))
-                       break;
-               udelay(1);
-               cond_resched();
-       } while (time_after_eq(timeout, jiffies));
+       msleep(1);
 
        oxygen_write8(chip, OXYGEN_2WIRE_MAP, map);
        oxygen_write8(chip, OXYGEN_2WIRE_DATA, data);