From: Herve Codina <herve.codina@xxxxxxxxxxx> commit c3cc3e69b33fee3d276895e0e2d1a8fb37ea5d0e upstream. The TRNSYNC feature is available (and enabled) only in transparent mode. Since commit 7cc9bda9c163 ("soc: fsl: cpm1: qmc: Handle timeslot entries at channel start() and stop()") TRNSYNC register is updated in transparent and hdlc mode. In hdlc mode, the address of the TRNSYNC register is used by the QMC for other internal purpose. Even if no weird results were observed in hdlc mode, touching this register in this mode is wrong. Update TRNSYNC only in transparent mode. Fixes: 7cc9bda9c163 ("soc: fsl: cpm1: qmc: Handle timeslot entries at channel start() and stop()") Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx> Reviewed-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Link: https://lore.kernel.org/r/20240808071132.149251-2-herve.codina@xxxxxxxxxxx Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/soc/fsl/qe/qmc.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) --- a/drivers/soc/fsl/qe/qmc.c +++ b/drivers/soc/fsl/qe/qmc.c @@ -940,11 +940,13 @@ static int qmc_chan_start_rx(struct qmc_ goto end; } - ret = qmc_setup_chan_trnsync(chan->qmc, chan); - if (ret) { - dev_err(chan->qmc->dev, "chan %u: setup TRNSYNC failed (%d)\n", - chan->id, ret); - goto end; + if (chan->mode == QMC_TRANSPARENT) { + ret = qmc_setup_chan_trnsync(chan->qmc, chan); + if (ret) { + dev_err(chan->qmc->dev, "chan %u: setup TRNSYNC failed (%d)\n", + chan->id, ret); + goto end; + } } /* Restart the receiver */ @@ -982,11 +984,13 @@ static int qmc_chan_start_tx(struct qmc_ goto end; } - ret = qmc_setup_chan_trnsync(chan->qmc, chan); - if (ret) { - dev_err(chan->qmc->dev, "chan %u: setup TRNSYNC failed (%d)\n", - chan->id, ret); - goto end; + if (chan->mode == QMC_TRANSPARENT) { + ret = qmc_setup_chan_trnsync(chan->qmc, chan); + if (ret) { + dev_err(chan->qmc->dev, "chan %u: setup TRNSYNC failed (%d)\n", + chan->id, ret); + goto end; + } } /* Patches currently in stable-queue which might be from herve.codina@xxxxxxxxxxx are queue-6.11/soc-fsl-cpm1-tsa-fix-tsa_write8.patch queue-6.11/soc-fsl-cpm1-qmc-update-trnsync-only-in-transparent-mode.patch