diff options
| author | Martin Povišer <povik+lin@cutebit.org> | 2023-02-24 16:33:01 +0100 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2023-02-24 16:31:19 +0000 |
| commit | d8b3e396088d787771f19fd3b7949e080dc31d6f (patch) | |
| tree | e46879578c397b27f106cad558d33181f9eef667 | |
| parent | aaf5f0d76b6e1870e3674408de2b13a92a4d4059 (diff) | |
| download | linux-rpi-d8b3e396088d787771f19fd3b7949e080dc31d6f.tar.gz linux-rpi-d8b3e396088d787771f19fd3b7949e080dc31d6f.tar.bz2 linux-rpi-d8b3e396088d787771f19fd3b7949e080dc31d6f.zip | |
ASoC: apple: mca: Fix SERDES reset sequence
Fix the reset sequence of reads and writes that we invoke from within
the early trigger. It looks like there never was a SERDES_CONF_SOME_RST
bit that should be involved in the reset sequence, and its presence in
the driver code is a mistake from earlier.
Instead, the reset sequence should go as follows: We should switch the
the SERDES unit's SYNC_SEL mux to the value of 7 (so outside the range
of 1...6 representing cluster's SYNCGEN units), then raise the RST bit
in SERDES_STATUS and wait for it to clear.
Properly resetting the SERDES unit fixes frame desynchronization hazard
in case of long frames (longer than 4 used slots). The desynchronization
manifests itself by rotating the PCM channels.
Fixes: 3df5d0d97289 ("ASoC: apple: mca: Start new platform driver")
Signed-off-by: Martin Povišer <povik+lin@cutebit.org>
Link: https://lore.kernel.org/r/20230224153302.45365-2-povik+lin@cutebit.org
Signed-off-by: Mark Brown <broonie@kernel.org>
| -rw-r--r-- | sound/soc/apple/mca.c | 18 |
1 files changed, 13 insertions, 5 deletions
diff --git a/sound/soc/apple/mca.c b/sound/soc/apple/mca.c index 9cceeb259952..aea08c7b2ee8 100644 --- a/sound/soc/apple/mca.c +++ b/sound/soc/apple/mca.c @@ -101,7 +101,6 @@ #define SERDES_CONF_UNK3 BIT(14) #define SERDES_CONF_NO_DATA_FEEDBACK BIT(15) #define SERDES_CONF_SYNC_SEL GENMASK(18, 16) -#define SERDES_CONF_SOME_RST BIT(19) #define REG_TX_SERDES_BITSTART 0x08 #define REG_RX_SERDES_BITSTART 0x0c #define REG_TX_SERDES_SLOTMASK 0x0c @@ -203,15 +202,24 @@ static void mca_fe_early_trigger(struct snd_pcm_substream *substream, int cmd, case SNDRV_PCM_TRIGGER_START: case SNDRV_PCM_TRIGGER_RESUME: case SNDRV_PCM_TRIGGER_PAUSE_RELEASE: + mca_modify(cl, serdes_conf, SERDES_CONF_SYNC_SEL, + FIELD_PREP(SERDES_CONF_SYNC_SEL, 0)); + mca_modify(cl, serdes_conf, SERDES_CONF_SYNC_SEL, + FIELD_PREP(SERDES_CONF_SYNC_SEL, 7)); mca_modify(cl, serdes_unit + REG_SERDES_STATUS, SERDES_STATUS_EN | SERDES_STATUS_RST, SERDES_STATUS_RST); - mca_modify(cl, serdes_conf, SERDES_CONF_SOME_RST, - SERDES_CONF_SOME_RST); - readl_relaxed(cl->base + serdes_conf); - mca_modify(cl, serdes_conf, SERDES_STATUS_RST, 0); + /* + * Experiments suggest that it takes at most ~1 us + * for the bit to clear, so wait 2 us for good measure. + */ + udelay(2); WARN_ON(readl_relaxed(cl->base + serdes_unit + REG_SERDES_STATUS) & SERDES_STATUS_RST); + mca_modify(cl, serdes_conf, SERDES_CONF_SYNC_SEL, + FIELD_PREP(SERDES_CONF_SYNC_SEL, 0)); + mca_modify(cl, serdes_conf, SERDES_CONF_SYNC_SEL, + FIELD_PREP(SERDES_CONF_SYNC_SEL, cl->no + 1)); break; default: break; |