diff options
| -rw-r--r-- | sound/soc/fsl/fsl_ssi.c | 52 |
1 files changed, 46 insertions, 6 deletions
diff --git a/sound/soc/fsl/fsl_ssi.c b/sound/soc/fsl/fsl_ssi.c index 939d1b8894dc..20ef09e1a395 100644 --- a/sound/soc/fsl/fsl_ssi.c +++ b/sound/soc/fsl/fsl_ssi.c @@ -577,8 +577,54 @@ static void fsl_ssi_rx_config(struct fsl_ssi_private *ssi_private, bool enable) fsl_ssi_config(ssi_private, enable, &ssi_private->rxtx_reg_val.rx); } +static void fsl_ssi_tx_ac97_saccst_setup(struct fsl_ssi_private *ssi_private) +{ + struct regmap *regs = ssi_private->regs; + + /* no SACC{ST,EN,DIS} regs on imx21-class SSI */ + if (!ssi_private->soc->imx21regs) { + /* + * Note that these below aren't just normal registers. + * They are a way to disable or enable bits in SACCST + * register: + * - writing a '1' bit at some position in SACCEN sets the + * relevant bit in SACCST, + * - writing a '1' bit at some position in SACCDIS unsets + * the relevant bit in SACCST register. + * + * The two writes below first disable all channels slots, + * then enable just slots 3 & 4 ("PCM Playback Left Channel" + * and "PCM Playback Right Channel"). + */ + regmap_write(regs, CCSR_SSI_SACCDIS, 0xff); + regmap_write(regs, CCSR_SSI_SACCEN, 0x300); + } +} + static void fsl_ssi_tx_config(struct fsl_ssi_private *ssi_private, bool enable) { + /* + * Why are we setting up SACCST everytime we are starting a + * playback? + * Some CODECs (like VT1613 CODEC on UDOO board) like to + * (sometimes) set extra bits in their SLOTREQ requests. + * When a bit is set in a SLOTREQ request then SSI sets the + * relevant bit in SACCST automatically (it is enough if a bit was + * set in a SLOTREQ just once, bits in SACCST are 'sticky'). + * If an extra slot gets enabled that's a disaster for playback + * because some of normal left or right channel samples are + * redirected instead to this extra slot. + * + * A workaround implemented in fsl-asoc-card of setting an + * appropriate CODEC register so that slots 3 & 4 (the normal + * stereo playback slots) are used for S/PDIF seems to mostly fix + * this issue on the UDOO board but since this CODEC is so + * untrustworthy let's play safe here and make sure that no extra + * slots are enabled every time a playback is started. + */ + if (enable && fsl_ssi_is_ac97(ssi_private)) + fsl_ssi_tx_ac97_saccst_setup(ssi_private); + fsl_ssi_config(ssi_private, enable, &ssi_private->rxtx_reg_val.tx); } @@ -633,12 +679,6 @@ static void fsl_ssi_setup_ac97(struct fsl_ssi_private *ssi_private) regmap_write(regs, CCSR_SSI_SACNT, CCSR_SSI_SACNT_AC97EN | CCSR_SSI_SACNT_FV); - /* no SACC{ST,EN,DIS} regs on imx21-class SSI */ - if (!ssi_private->soc->imx21regs) { - regmap_write(regs, CCSR_SSI_SACCDIS, 0xff); - regmap_write(regs, CCSR_SSI_SACCEN, 0x300); - } - /* * Enable SSI, Transmit and Receive. AC97 has to communicate with the * codec before a stream is started. |