[PATCH RFC 03/10] drm/i2c: tda998x: avoid racy access to mode clock

[Russell King]

Avoid a racy access to the mode clock by storing the current mode clock
during a mode set under the audio mutex.  This allows us to access it
from the audio path in a safe way.

Signed-off-by: Russell King <rmk+kernel at armlinux.org.uk>
---
 drivers/gpu/drm/i2c/tda998x_drv.c | 18 +++++++-----------
 1 file changed, 7 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c 
b/drivers/gpu/drm/i2c/tda998x_drv.c
index 495ee3fed661..858237f7f4d6 100644
--- a/drivers/gpu/drm/i2c/tda998x_drv.c
+++ b/drivers/gpu/drm/i2c/tda998x_drv.c
@@ -48,6 +48,7 @@ struct tda998x_priv {
        u8 vip_cntrl_0;
        u8 vip_cntrl_1;
        u8 vip_cntrl_2;
+       unsigned long tdms_clock;
        struct tda998x_audio_params audio_params;

        struct platform_device *audio_pdev;
@@ -714,8 +715,7 @@ static void tda998x_audio_mute(struct tda998x_priv *priv, 
bool on)

 static int
 tda998x_configure_audio(struct tda998x_priv *priv,
-                       struct tda998x_audio_params *params,
-                       unsigned mode_clock)
+                       struct tda998x_audio_params *params)
 {
        u8 buf[6], clksel_aip, clksel_fs, cts_n, adiv;
        u32 n;
@@ -772,7 +772,7 @@ tda998x_configure_audio(struct tda998x_priv *priv,
         * assume 100MHz requires larger divider.
         */
        adiv = AUDIO_DIV_SERCLK_8;
-       if (mode_clock > 100000)
+       if (priv->tdms_clock > 100000)
                adiv++;                 /* AUDIO_DIV_SERCLK_16 */

        /* S/PDIF asks for a larger divider */
@@ -1077,10 +1077,10 @@ tda998x_encoder_mode_set(struct drm_encoder *encoder,

                tda998x_write_avi(priv, adjusted_mode);

+               priv->tdms_clock = adjusted_mode->clock;
+
                if (priv->audio_params.format != AFMT_UNUSED)
-                       tda998x_configure_audio(priv,
-                                               &priv->audio_params,
-                                               adjusted_mode->clock);
+                       tda998x_configure_audio(priv, &priv->audio_params);
        }

        priv->is_hdmi_config = priv->is_hdmi_sink;
@@ -1230,9 +1230,6 @@ static int tda998x_audio_hw_params(struct device *dev, 
void *data,
                .cea = params->cea,
        };

-       if (!priv->encoder.crtc)
-               return -ENODEV;
-
        memcpy(audio.status, params->iec.status,
               min(sizeof(audio.status), sizeof(params->iec.status)));

@@ -1270,8 +1267,7 @@ static int tda998x_audio_hw_params(struct device *dev, 
void *data,
        mutex_lock(&priv->audio_mutex);
        /* We must not program the TDA998x for audio if the sink is DVI. */
        if (priv->is_hdmi_config)
-               ret = tda998x_configure_audio(priv, &audio,
-                                             priv->encoder.crtc->hwmode.clock);
+               ret = tda998x_configure_audio(priv, &audio);
        else
                ret = 0;

-- 
2.1.0