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authorVladimir Oltean <vladimir.oltean@nxp.com>2020-03-05 00:00:44 +0200
committerMark Brown <broonie@kernel.org>2020-03-05 14:06:24 +0000
commite9bac90036d394b01cc7d5297a11d33b8ab92a91 (patch)
tree61c6d289b2d49e4ad2e18c2f2887125654c727b0 /drivers/spi
parentea93ed4c181bd42d27b49b612d56f4ceb23d1d6c (diff)
spi: spi-fsl-dspi: Take software timestamp in dspi_fifo_write
Although the SPI system timestamps are supposed to reflect the moment that the peripheral has received a word rather than the moment when the CPU has enqueued that word to the FIFO, in practice it is easier to just record the latter time than the former (with a smaller error). With the recent migration of TCFQ users from poll back to interrupt mode (this time for XSPI FIFO), it's wiser to keep the interrupt latency outside of the measurement of the PTP system timestamp itself. If there proves to be any constant offset that requires static compensation, that can always be added later. So far that does not appear to be the case at least on the LS1021A-TSN board, where testing shows that the phc2sys offset is able to remain within +/- 200 ns even after 68 hours of testing. Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Link: https://lore.kernel.org/r/20200304220044.11193-13-olteanv@gmail.com Signed-off-by: Mark Brown <broonie@kernel.org>
Diffstat (limited to 'drivers/spi')
-rw-r--r--drivers/spi/spi-fsl-dspi.c19
1 files changed, 9 insertions, 10 deletions
diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index d5983be32180..b5ab0afbfa26 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -838,19 +838,18 @@ no_accel:
static void dspi_fifo_write(struct fsl_dspi *dspi)
{
+ struct spi_transfer *xfer = dspi->cur_transfer;
+ struct spi_message *msg = dspi->cur_msg;
+ int bytes_sent;
+
dspi_setup_accel(dspi);
+ spi_take_timestamp_pre(dspi->ctlr, xfer, dspi->progress, !dspi->irq);
+
if (dspi->devtype_data->trans_mode == DSPI_EOQ_MODE)
dspi_eoq_fifo_write(dspi);
else
dspi_xspi_fifo_write(dspi);
-}
-
-static int dspi_rxtx(struct fsl_dspi *dspi)
-{
- struct spi_transfer *xfer = dspi->cur_transfer;
- struct spi_message *msg = dspi->cur_msg;
- int bytes_sent;
/* Update total number of bytes that were transferred */
bytes_sent = dspi->words_in_flight * dspi->oper_word_size;
@@ -859,16 +858,16 @@ static int dspi_rxtx(struct fsl_dspi *dspi)
spi_take_timestamp_post(dspi->ctlr, dspi->cur_transfer,
dspi->progress, !dspi->irq);
+}
+static int dspi_rxtx(struct fsl_dspi *dspi)
+{
dspi_fifo_read(dspi);
if (!dspi->len)
/* Success! */
return 0;
- spi_take_timestamp_pre(dspi->ctlr, dspi->cur_transfer,
- dspi->progress, !dspi->irq);
-
dspi_fifo_write(dspi);
return -EINPROGRESS;