drm/i2c: tda998x: avoid race in tda998x_encoder_mode_set()

As priv->audio_params can now be changed at run time, we need to be more
careful about how we deal with a mode set.  We must take the audio lock
while checking if there's a valid audio configuration.

However, it's slightly worse than that - during mode set, we mute the
audio, and it must not be unmuted until we have finished the mode set.
It is possible that the audio side may start while a mode set is in
progress, so take the audio_mutex lock around the whole mode setting
procedure.

Tested-by: Jon Medhurst <tixy@linaro.org>
Acked-by: Jon Medhurst <tixy@linaro.org>
Tested-by: Jyri Sarha <jsarha@ti.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c
index 168c0b4..9184487 100644 (file)
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -1074,13 +1074,12 @@ tda998x_encoder_mode_set(struct drm_encoder *encoder,
 
                tda998x_write_avi(priv, adjusted_mode);
 
-               if (priv->audio_params.format != AFMT_UNUSED) {
-                       mutex_lock(&priv->audio_mutex);
+               mutex_lock(&priv->audio_mutex);
+               if (priv->audio_params.format != AFMT_UNUSED)
                        tda998x_configure_audio(priv,
                                                &priv->audio_params,
                                                adjusted_mode->clock);
-                       mutex_unlock(&priv->audio_mutex);
-               }
+               mutex_unlock(&priv->audio_mutex);
        }
 }